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  • 101. Purushotham, P.
    et al.
    Cho, S. H.
    Díaz-Moreno, Sara M
    KTH, School of Biotechnology (BIO), Glycoscience.
    Kumar, M.
    Nixon, B. T.
    Bulone, Vincent
    KTH, School of Biotechnology (BIO), Glycoscience. Univ Adelaide, Australia.
    Zimmer, J.
    A single heterologously expressed plant cellulose synthase isoform is sufficient for cellulose microfibril formation in vitro2016In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 113, no 40, p. 11360-11365Article in journal (Refereed)
    Abstract [en]

    Plant cell walls are a composite material of polysaccharides, proteins, and other noncarbohydrate polymers. In the majority of plant tissues, the most abundant polysaccharide is cellulose, a linear polymer of glucose molecules. As the load-bearing component of the cell wall, individual cellulose chains are frequently bundled into micro and macrofibrils and are wrapped around the cell. Cellulose is synthesized by membrane-integrated and processive glycosyltransferases that polymerize UDP-activated glucose and secrete the nascent polymer through a channel formed by their own transmembrane regions. Plants express several different cellulose synthase isoforms during primary and secondary cell wall formation; however, so far, none has been functionally reconstituted in vitro for detailed biochemical analyses. Here we report the heterologous expression, purification, and functional reconstitution of Populus tremula x tremuloides CesA8 (PttCesA8), implicated in secondary cell wall formation. The recombinant enzyme polymerizes UDP-activated glucose to cellulose, as determined by enzyme degradation, permethylation glycosyl linkage analysis, electron microscopy, and mutagenesis studies. Catalytic activity is dependent on the presence of a lipid bilayer environment and divalent manganese cations. Further, electron microscopy analyses reveal that PttCesA8 produces cellulose fibers several micrometers long that occasionally are capped by globular particles, likely representing PttCesA8 complexes. Deletion of the enzyme's N-terminal RING-finger domain almost completely abolishes fiber formation but not cellulose biosynthetic activity. Our results demonstrate that reconstituted PttCesA8 is not only sufficient for cellulose biosynthesis in vitro but also suffices to bundle individual glucan chains into cellulose microfibrils.

  • 102.
    Rajangam, Alex S.
    et al.
    KTH, School of Biotechnology (BIO), Centres, Swedish Center for Biomimetic Fiber Engineering, BioMime.
    Kumar, Manoj
    Aspeborg, Henrik
    KTH, School of Biotechnology (BIO), Centres, Swedish Center for Biomimetic Fiber Engineering, BioMime.
    Guerriero, Gea
    KTH, School of Biotechnology (BIO), Centres, Swedish Center for Biomimetic Fiber Engineering, BioMime.
    Arvestad, Lars
    KTH, School of Computer Science and Communication (CSC), Computational Biology, CB.
    Pansri, Podjamas
    KTH, School of Biotechnology (BIO), Centres, Swedish Center for Biomimetic Fiber Engineering, BioMime.
    Brown, Christian J. L.
    KTH, School of Biotechnology (BIO), Centres, Swedish Center for Biomimetic Fiber Engineering, BioMime.
    Hober, Sophia
    KTH, School of Biotechnology (BIO), Proteomics (closed 20130101).
    Blomqvist, Kristina
    KTH, School of Biotechnology (BIO), Centres, Swedish Center for Biomimetic Fiber Engineering, BioMime.
    Divne, Christina
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Biotechnology (BIO), Centres, Swedish Center for Biomimetic Fiber Engineering, BioMime.
    Ezcurra, Inés
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Biotechnology (BIO), Centres, Swedish Center for Biomimetic Fiber Engineering, BioMime.
    Mellerowicz, Ewa
    Sundberg, Bjorn
    Bulone, Vincent
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Biotechnology (BIO), Centres, Swedish Center for Biomimetic Fiber Engineering, BioMime.
    Teeri, Tuula T.
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Biotechnology (BIO), Centres, Swedish Center for Biomimetic Fiber Engineering, BioMime.
    MAP20, a Microtubule-Associated Protein in the Secondary Cell Walls of Hybrid Aspen, Is a Target of the Cellulose Synthesis Inhibitor 2,6-Dichlorobenzonitrile2008In: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 148, no 3, p. 1283-1294Article in journal (Refereed)
    Abstract [en]

    We have identified a gene, denoted PttMAP20, which is strongly up-regulated during secondary cell wall synthesis and tightly coregulated with the secondary wall-associated CESA genes in hybrid aspen (Populus tremula x tremuloides). Immunolocalization studies with affinity-purified antibodies specific for PttMAP20 revealed that the protein is found in all cell types in developing xylem and that it is most abundant in cells forming secondary cell walls. This PttMAP20 protein sequence contains a highly conserved TPX2 domain first identified in a microtubule-associated protein (MAP) in Xenopus laevis. Overexpression of PttMAP20 in Arabidopsis (Arabidopsis thaliana) leads to helical twisting of epidermal cells, frequently associated with MAPs. In addition, a PttMAP20-yellow fluorescent protein fusion protein expressed in tobacco (Nicotiana tabacum) leaves localizes to microtubules in leaf epidermal pavement cells. Recombinant PttMAP20 expressed in Escherichia coli also binds specifically to in vitro-assembled, taxol-stabilized bovine microtubules. Finally, the herbicide 2,6-dichlorobenzonitrile, which inhibits cellulose synthesis in plants, was found to bind specifically to PttMAP20. Together with the known function of cortical microtubules in orienting cellulose microfibrils, these observations suggest that PttMAP20 has a role in cellulose biosynthesis.

  • 103. Roberts, Alison W.
    et al.
    Lahnstein, Jelle
    Hsieh, Yves S. Y.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience.
    Xing, Xiaohui
    Yap, Kuok
    Chaves, Arielle M
    Scavuzzo-Duggan, Tess R
    Dimitroff, George
    Lonsdale, Andrew
    Roberts, Eric M.
    Bulone, Vincent
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience.
    Fincher, Geoffrey B
    Doblin, Monika Susanne
    Bacic, Antony
    Burton, Rachel A
    Functional Characterization of a Glycosyltransferase from the Moss Physcomitrella patens Involved in the Biosynthesis of a Novel Cell Wall Arabinoglucan2018In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 30, no 6, p. 1293-1308Article in journal (Refereed)
    Abstract [en]

    Mixed-linkage (1,3;1,4)-β-glucan (MLG), an abundant cell wall polysaccharide in the Poaceae, has been detected in ascomycetes, algae, and seedless vascular plants, but not in eudicots. Although MLG has not been reported in bryophytes, a predicted glycosyltransferase from the moss Physcomitrella patens (Pp3c12_24670) is similar to a bona fide ascomycete MLG synthase. We tested whether Pp3c12_24670 encodes an MLG synthase by expressing it in wild tobacco (Nicotiana benthamiana) and testing for release of diagnostic oligosaccharides from the cell walls by either lichenase or (1,4)-β-glucan endohydrolase. Lichenase, an MLG-specific endohydrolase, showed no activity against cell walls from transformed N. benthamiana, but (1,4)-β-glucan endohydrolase released oligosaccharides that were distinct from oligosaccharides released from MLG by this enzyme. Further analysis revealed that these oligosaccharides were derived from a novel unbranched, unsubstituted arabinoglucan (AGlc) polysaccharide. We identified sequences similar to the P. patens AGlc synthase from algae, bryophytes, lycophytes, and monilophytes, raising the possibility that other early divergent plants synthesize AGlc. Similarity of P. patens AGlc synthase to MLG synthases from ascomycetes, but not those from Poaceae, suggests that AGlc and MLG have a common evolutionary history that includes loss in seed plants, followed by a more recent independent origin of MLG within the monocots.

  • 104. Ruprecht, Colin
    et al.
    Tohge, Takayuki
    Fernie, Alisdair
    Mortimer, Cara L.
    Kozlo, Amanda
    Fraser, Paul D.
    Funke, Norma
    Cesarino, Igor
    Vanholme, Ruben
    Boerjan, Wout
    Morreel, Kris
    Burgert, Ingo
    Gierlinger, Notburga
    Bulone, Vincent
    KTH, School of Biotechnology (BIO), Glycoscience.
    Schneider, Vera
    Stockero, Andrea
    Navarro, Juan Pedro
    Pudel, Frank
    Tambuyser, Bart
    Hygate, James
    Bumstead, Jon
    Notley, Louis
    Persson, Staffan
    Transcript and Metabolite Profiling for the Evaluation of Tobacco Tree and Poplar as Feedstock for the Bio-based Industry2014In: Journal of Visualized Experiments, ISSN 1940-087X, E-ISSN 1940-087X, no 87, p. e51393-Article in journal (Refereed)
    Abstract [en]

    The global demand for food, feed, energy and water poses extraordinary challenges for future generations. It is evident that robust platforms for the exploration of renewable resources are necessary to overcome these challenges. Within the multinational framework MultiBioPro we are developing biorefinery pipelines to maximize the use of plant biomass. More specifically, we use poplar and tobacco tree (Nicotiana glauca) as target crop species for improving saccharification, isoprenoid, long chain hydrocarbon contents, fiber quality, and suberin and lignin contents. The methods used to obtain these outputs include GC-MS, LC-MS and RNA sequencing platforms. The metabolite pipelines are well established tools to generate these types of data, but also have the limitations in that only well characterized metabolites can be used. The deep sequencing will allow us to include all transcripts present during the developmental stages of the tobacco tree leaf, but has to be mapped back to the sequence of Nicotiana tabacum. With these set-ups, we aim at a basic understanding for underlying processes and at establishing an industrial framework to exploit the outcomes. In a more long term perspective, we believe that data generated here will provide means for a sustainable biorefinery process using poplar and tobacco tree as raw material. To date the basal level of metabolites in the samples have been analyzed and the protocols utilized are provided in this article.

  • 105.
    Ruthes, Andrea C.
    et al.
    KTH, School of Biotechnology (BIO), Glycoscience.
    Martinez-Abad, Antonio
    KTH, School of Biotechnology (BIO), Glycoscience.
    Tan, Hwei-Ting
    KTH, School of Biotechnology (BIO), Glycoscience. Univ Adelaide, Australia.
    Bulone, Vincent
    KTH, School of Biotechnology (BIO), Glycoscience. Univ Adelaide, Australia.
    Vilaplana, Francisco
    KTH, School of Biotechnology (BIO), Glycoscience.
    Sequential fractionation of feruloylated hemicelluloses and oligosaccharides from wheat bran using subcritical water and xylanolytic enzymes2017In: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, Vol. 19, no 8, p. 1919-1931Article in journal (Refereed)
    Abstract [en]

    Wheat bran is a major by-product of cereal production that still has limited use for advanced nutritional and material applications. A sequential process using subcritical water, membrane filtration and selective enzymatic treatments has been designed for the combined fractionation of functional high molar mass hemicelluloses (over 10(5) g mol(-1)) and oligosaccharides from wheat bran. This process not only offers increased total solid yield compared with conventional protocols based on alkaline extraction, but it also preserves the inherent functionalities of the phenolic groups that substitute the carbohydrate structures of the extracted hemicelluloses. Feruloylated arabinoxylans (F-AX) with high molar mass and significant radical scavenging activity can be isolated from the subcritical water extract. Structurally different oligosaccharides, including mixed-linkage beta-D-glucan oligosaccharides (BGOs) and arabinoxylo-oligosaccharides (AXOs) can be recovered from the eluent after membrane filtration. The crosslinked residue after subcritical water extraction was further treated with xylanolytic enzymes to release valuable feruloylated arabinoxylo-oligosaccharides (FAXOs). The oligo-and polysaccharide fractions isolated from this sequential process show great potential for use as prebiotic or platform chemicals, and as polymeric matrices for carbohydrate-based materials with radical scavenging properties, respectively.

  • 106. Samalova, Marketa
    et al.
    Melida, Hugo
    KTH, School of Biotechnology (BIO), Glycoscience.
    Vilaplana, Francisco
    KTH, School of Biotechnology (BIO), Glycoscience.
    Bulone, Vincent
    KTH, School of Biotechnology (BIO), Glycoscience.
    Soanes, Darren M.
    Talbot, Nicholas J.
    Gurr, Sarah J.
    The beta-1,3-glucanosyltransferases (Gels) affect the structure of the rice blast fungal cell wall during appressorium-mediated plant infection2017In: Cellular Microbiology, ISSN 1462-5814, E-ISSN 1462-5822, Vol. 19, no 3, article id UNSP e12659Article in journal (Refereed)
    Abstract [en]

    The fungal wall is pivotal for cell shape and function, and in interfacial protection during host infection and environmental challenge. Here, we provide the first description of the carbohydrate composition and structure of the cell wall of the rice blast fungus Magnaporthe oryzae. We focus on the family of glucan elongation proteins (Gels) and characterize five putative beta-1,3-glucan glucanosyltransferases that each carry the Glycoside Hydrolase 72 signature. We generated targeted deletion mutants of all Gel isoforms, that is, the GH72(+), which carry a putative carbohydrate-binding module, and the GH72(-)Gels, without this motif. We reveal that M. oryzae GH72(+) GELs are expressed in spores and during both infective and vegetative growth, but each individual Gel enzymes are dispensable for pathogenicity. Further, we demonstrated that Delta gel1 Delta gel3 Delta gel4 null mutant has a modified cell wall in which 1,3-glucans have a higher degree of polymerization and are less branched than the wild-type strain. The mutant showed significant differences in global patterns of gene expression, a hyper-branching phenotype and no sporulation, and thus was unable to cause rice blast lesions (except via wounded tissues). We conclude that Gel proteins play significant roles in structural modification of the fungal cell wall during appressorium-mediated plant infection.

  • 107. Sandh, Gustaf
    et al.
    Ran, Liang
    Xu, Linghua
    Sundqvist, Gustav
    KTH, School of Biotechnology (BIO), Glycoscience.
    Bulone, Vincent
    KTH, School of Biotechnology (BIO), Glycoscience.
    Bergman, Birgitta
    Comparative proteomic profiles of the marine cyanobacterium Trichodesmium erythraeum IMS101 under different nitrogen regimes2011In: Proteomics, ISSN 1615-9853, E-ISSN 1615-9861, Vol. 11, no 3, p. 406-419Article in journal (Refereed)
    Abstract [en]

    Trichodesmium is a marine filamentous diazotrophic cyanobacterium and an important contributor of "new" nitrogen in the oligotrophic surface waters of the tropical and subtropical oceans. It is unique in that it exclusively fixes N-2 at daytime, although it belongs to the non-heterocystous filamentous segment of the cyanobacterial radiation. Here we present the first quantitative proteomic analysis of Trichodesmium erythraeum IMS101 when grown under different nitrogen regimes using 2-DE/MALDI-TOF-MS. Addition of combined nitrogen (NO3-) prevented development of the morphological characteristics of the N-2-fixing cell type (diazocytes), inhibited expression of the nitrogenase enzyme subunits and consequently N-2 fixation activity. The diazotrophic regime (N-2 versus NO3- cultures) elicited the differential expression of more than 100 proteins, which represented 13.5% of the separated proteins. Besides proteins directly related to N-2 fixation, proteins involved in the synthesis of reducing equivalents and the generation of a micro-oxic environment were strongly up-regulated, as was in particular Dps, a protein related to iron acquisition and potentially other vital cellular processes. In contrast, proteins involved in the S-adenosylmethionine (SAM) cycle, synthesis of amino acids and production of carbon skeletons for storage and synthesis of amino acids were suppressed. The data are discussed in the context of Trichodesmium's unusual N-2-fixing physiology.

  • 108. Saraiva, Marcia
    et al.
    De Bruijn, Irene
    Grenville-Briggs, Laura
    KTH, School of Biotechnology (BIO), Glycoscience. Aberdeen Oomycete Laboratory, University of Aberdeen, United Kingdom; Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Sweden.
    Mclaggan, Debbie
    Willems, Ariane
    Bulone, Vincent
    KTH, School of Biotechnology (BIO), Glycoscience.
    Van West, Pieter
    Functional characterization of a tyrosinase gene from the oomycete Saprolegnia parasitica by RNAi silencing2014In: Fungal Biology, ISSN 1878-6146, E-ISSN 1878-6162, Vol. 118, no 7, p. 621-629Article in journal (Refereed)
    Abstract [en]

    Here we describe the first application of transient gene silencing in Saprolegnia parasitica, a pathogenic oomycete that infects a wide range of fish, amphibians, and crustaceans. A gene encoding a putative tyrosinase from S. parasitica, SpTyr, was selected to investigate the suitability of RNA-interference (RNAi) to functionally characterize genes of this economically important pathogen. Tyrosinase is a mono-oxygenase enzyme that catalyses the O-hydroxylation of monophenols and subsequent oxidation of O-diphenols to quinines. These enzymes are widely distributed in nature, and are involved in the melanin biosynthesis. Gene silencing was obtained by delivering in vitro synthesized SpTyr dsRNA into protoplasts. Expression analysis, tyrosinase activity measurements, and melanin content analysis confirmed silencing in individual lines. Silencing of SpTyr resulted in a decrease of tyrosinase activity between 38 % and 60 %, dependent on the level of SpTyr-expression achieved. The SpTyr-silenced lines displayed less pigmentation in developing sporangia and occasionally an altered morphology. Moreover, developing sporangia from individual silenced lines possessed a less electron dense cell wall when compared to control lines, treated with GFP-dsRNA. In conclusion, the tyrosinase gene of S. parasitica is required for melanin formation and transient gene silencing can be used to functionally characterize gene S in S. parasitica.

  • 109. Schrick, Kathrin
    et al.
    DeBolt, Seth
    Bulone, Vincent
    KTH, School of Biotechnology (BIO), Glycoscience.
    Deciphering the molecular functions of sterols in cellulose biosynthesis2012In: Frontiers in Plant Science, ISSN 1664-462X, E-ISSN 1664-462X, Vol. 3, p. 84-Article in journal (Refereed)
    Abstract [en]

    Sterols play vital roles in plant growth and development, as components of membranes and as precursors to steroid hormones. Analysis of Arabidopsis mutants indicates that sterol composition is crucial for cellulose biosynthesis. Sterols are widespread in the plasma membrane (PM), suggesting a possible link between sterols and the multimeric cellulose synthase complex. In one possible scenario, molecular interactions in sterol-rich PM microdomains or another form of sterol-dependent membrane scaffolding may be critical for maintaining the correct subcellular localization, structural integrity and/or activity of the cellulose synthase machinery. Another possible link may be through steryl glucosides, which could act as primers for the attachment of glucose monomers during the synthesis of beta - (1 -> 4) glucan chains that form the cellulose microfibrils. This mini-review examines genetic and biochemical data supporting the link between sterols and cellulose biosynthesis in cell wall formation and explores potential approaches to elucidate the mechanism of this association.

  • 110.
    Shao, Zhanru
    et al.
    Chinese Acad Sci, Inst Oceanol, CAS Key Lab Expt Marine Biol, Qingdao 266071, Peoples R China.;PSL Res Univ, Ecole Normale Super, IBENS, CNRS,INSERM, F-75005 Paris, France.;Qingdao Natl Lab Marine Sci & Technol, Lab Marine Biol & Biotechnol, Qingdao 266237, Peoples R China.;Chinese Acad Sci, Ctr Ocean Mega Sci, Qingdao 266071, Peoples R China..
    Thomas, Yann
    PSL Res Univ, Ecole Normale Super, IBENS, CNRS,INSERM, F-75005 Paris, France..
    Hembach, Lea
    Westphalian Wilhelms Univ Munster, Inst Plant Biol & Biotechnol, D-48143 Munster, Germany..
    Xing, Xiaohui
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH). Royal Inst Technol KTH, AlbaNova Univ Ctr, Sch Biotechnol, Div Glycosci, SE-10691 Stockholm, Sweden..
    Duan, Delin
    Chinese Acad Sci, Inst Oceanol, CAS Key Lab Expt Marine Biol, Qingdao 266071, Peoples R China.;Qingdao Natl Lab Marine Sci & Technol, Lab Marine Biol & Biotechnol, Qingdao 266237, Peoples R China.;Chinese Acad Sci, Ctr Ocean Mega Sci, Qingdao 266071, Peoples R China..
    Moerschbacher, Bruno M.
    Westphalian Wilhelms Univ Munster, Inst Plant Biol & Biotechnol, D-48143 Munster, Germany..
    Bulone, Vincent
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience.
    Tirichine, Leila
    PSL Res Univ, Ecole Normale Super, IBENS, CNRS,INSERM, F-75005 Paris, France..
    Bowler, Chris
    PSL Res Univ, Ecole Normale Super, IBENS, CNRS,INSERM, F-75005 Paris, France..
    Comparative characterization of putative chitin deacetylases from Phaeodactylum tricornutum and Thalassiosira pseudonana highlights the potential for distinct chitin-based metabolic processes in diatoms2019In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 221, no 4, p. 1890-1905Article in journal (Refereed)
    Abstract [en]

    Chitin is generally considered to be present in centric diatoms but not in pennate species. Many aspects of chitin biosynthetic pathways have not been explored in diatoms. We retrieved chitin metabolic genes from pennate (Phaeodactylum tricornutum) and centric (Thalassiosira pseudonana) diatom genomes. Chitin deacetylase (CDA) genes from each genome (PtCDA and TpCDA) were overexpressed in P. tricornutum. We performed comparative analysis of their sequence structure, phylogeny, transcriptional profiles, localization and enzymatic activities. The chitin relevant proteins show complex subcellular compartmentation. PtCDA was likely acquired by horizontal gene transfer from prokaryotes, whereas TpCDA has closer relationships with sequences in Opisthokonta. Using transgenic P. tricornutum lines expressing CDA-green fluorescent protein (GFP) fusion proteins, PtCDA predominantly localizes to Golgi apparatus whereas TpCDA localizes to endoplasmic reticulum/chloroplast endoplasmic reticulum membrane. CDA-GFP overexpression upregulated the transcription of chitin synthases and potentially enhanced the ability of chitin synthesis. Although both CDAs are active on GlcNAc(5), TpCDA is more active on the highly acetylated chitin polymer DA60. We have addressed the ambiguous characters of CDAs from P. tricornutum and T. pseudonana. Differences in localization, evolution, expression and activities provide explanations underlying the greater potential of centric diatoms for chitin biosynthesis. This study paves the way for in vitro applications of novel CDAs.

  • 111. Song, Chunxu
    et al.
    Sundqvist, Gustav
    KTH, School of Biotechnology (BIO), Glycoscience.
    Malm, Erik
    KTH, School of Biotechnology (BIO), Glycoscience.
    de Bruijn, Irene
    Kumar, Aundy
    van de Mortel, Judith
    Bulone, Vincent
    KTH, School of Biotechnology (BIO), Glycoscience.
    Raaijmakers, Jos M.
    Lipopeptide biosynthesis in Pseudomonas fluorescens is regulated by the protease complex ClpAP2015In: BMC Microbiology, ISSN 1471-2180, E-ISSN 1471-2180, Vol. 15, article id 29Article in journal (Refereed)
    Abstract [en]

    Background: Lipopeptides (LP) are structurally diverse compounds with potent surfactant and broad-spectrum antibiotic activities. In Pseudomonas and other bacterial genera, LP biosynthesis is governed by large multimodular nonribosomal peptide synthetases (NRPS). To date, relatively little is known about the regulatory genetic network of LP biosynthesis. Results: This study provides evidence that the chaperone ClpA, together with the serine protease ClpP, regulates the biosynthesis of the LP massetolide in Pseudomonas fluorescens SS101. Whole-genome transcriptome analyses of clpA and clpP mutants showed their involvement in the transcription of the NRPS genes massABC and the transcriptional regulator massAR. In addition, transcription of genes associated with cell wall and membrane biogenesis, energy production and conversion, amino acid transport and metabolism, and pilus assembly were altered by mutations in clpA and clpP. Proteome analysis allowed the identification of additional cellular changes associated to clpA and clpP mutations. The expression of proteins of the citrate cycle and the heat shock proteins DnaK and DnaJ were particularly affected. Combined with previous findings, these results suggest that the ClpAP complex regulates massetolide biosynthesis via the pathway-specific, LuxR-type regulator MassAR, the heat shock proteins DnaK and DnaJ, and proteins of the TCA cycle. Conclusions: Combining transcriptome and proteome analyses provided new insights into the regulation of LP biosynthesis in P. fluorescens and led to the identification of specific missing links in the regulatory pathways.

  • 112. Soultani-Vigneron, S.
    et al.
    Dugas, V.
    Rouillat, M. H.
    Fedolliere, J.
    Duclos, M. C.
    Vnuk, E.
    Phaner-Goutorbe, M.
    Bulone, Vincent
    KTH, School of Biotechnology (BIO), Glycoscience.
    Martin, J. R.
    Wallach, J.
    Cloarec, J. P.
    Immobilisation of oligo-peptidic probes for microarray implementation: Characterisation by FTIR, Atomic Force Microscopy and 2D fluorescence2005In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 822, no 02-jan, p. 304-310Article in journal (Refereed)
    Abstract [en]

    Proteomic microarrays show a wide range of applications for the investigation of DNA-protein, enzyme-substrate as well as protein-protein interactions. Among many challenges to build a viable protein microarray, the surface chemistry that will allow to immobilised various proteins to retain their biological activity is of paramount importance. Here we report a chemical functionalisation method allowing immobilisation of oligo-peptides onto silica surface (porous silica, glass, thermal silicon dioxide). Substrates were first derivatised with a monofunctional silane allowing the elaboration of dense and uniform monolayers in highly reproducible way. Prior to the oligo-peptides grafting, this organic layer was functionalised with an amino-polyethyleneglycol. The coupling step of oligo-peptides onto functionalised supports is achieved through activation of the C-terminal function of the oligo-peptides. Chemical surface modifications were followed by FTIR spectroscopy, AFM measurements and fluorescence scanning microscopy. A systematic study of the oligo-peptide grafting conditions (time, concentration, solvent) was carried out to optimise this step. The oligo-peptides grafting strategy implemented in this work ensure a covalent and oriented grafting of the oligo-peptides. This orientation is ensured through the use of fully protected peptide except the terminal primary an-tine. The immobilized peptides will be then deprotected before biological recognition. This strategy is crucial to retain the biological activity of thousands of oligo-probes assessed on a microarray.

  • 113.
    Srivastava, Vaibhav
    et al.
    KTH, School of Biotechnology (BIO), Glycoscience.
    Malm, Erik
    KTH, School of Biotechnology (BIO), Glycoscience.
    Sundqvist, Gustav
    KTH, School of Biotechnology (BIO), Glycoscience.
    Bulone, Vincent
    KTH, School of Biotechnology (BIO), Glycoscience.
    Quantitative Proteomics Reveals that Plasma Membrane Microdomains From Poplar Cell Suspension Cultures Are Enriched in Markers of Signal Transduction, Molecular Transport, and Callose Biosynthesis2013In: Molecular & Cellular Proteomics, ISSN 1535-9476, E-ISSN 1535-9484, Vol. 12, no 12, p. 3874-3885Article in journal (Refereed)
    Abstract [en]

    The plasma membrane (PM) is a highly dynamic interface that contains detergent-resistant microdomains (DRMs). The aim of this work was to determine the main functions of such microdomains in poplar through a proteomic analysis using gel-based and solution (iTRAQ) approaches. A total of 80 proteins from a limited number of functional classes were found to be significantly enriched in DRM relative to PM. The enriched proteins are markers of signal transduction, molecular transport at the PM, or cell wall biosynthesis. Their intrinsic properties are presented and discussed together with the biological significance of their enrichment in DRM. Of particular importance is the significant and specific enrichment of several callose [(1→3)-β-glucan] synthase isoforms, whose catalytic activity represents a final response to stress, leading to the deposition of callose plugs at the surface of the PM. An integrated functional model that connects all DRM-enriched proteins identified is proposed. This report is the only quantitative analysis available to date of the protein composition of membrane microdomains from a tree species.

  • 114.
    Srivastava, Vaibhav
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience.
    Rezinciuc, Svetlana
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience.
    Bulone, Vincent
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience. University of Adelaide, Australia.
    Quantitative proteomic analysis of four developmental stages of Saprolegnia parasitica2018In: Frontiers in Microbiology, ISSN 1664-302X, E-ISSN 1664-302X, Vol. 8, no Jan, article id 2658Article in journal (Refereed)
    Abstract [en]

    Several water mold species from the Saprolegnia genus infect fish, amphibians, and crustaceans in natural ecosystems and aquaculture farms. Saprolegnia parasitica is one of the most severe fish pathogens. It is responsible for millions of dollars of losses to the aquaculture industry worldwide. Here, we have performed a proteomic analysis, using gel-based and solution (iTRAQ) approaches, of four defined developmental stages of S. parasitica grown in vitro, i.e., the mycelium, primary cysts, secondary cysts and germinated cysts, to gain greater insight into the types of proteins linked to the different stages. A relatively high number of kinases as well as virulence proteins, including the ricin B lectin, disintegrins, and proteases were identified in the S. parasitica proteome. Many proteins associated with various biological processes were significantly enriched in different life cycle stages of S. parasitica. Compared to the mycelium, most of the proteins in the different cyst stages showed similar enrichment patterns and were mainly related to energy metabolism, signal transduction, protein synthesis, and post-translational modifications. The proteins most enriched in the mycelium compared to the cyst stages were associated with amino acid metabolism, carbohydrate metabolism, and mitochondrial energy production. The data presented expand our knowledge of metabolic pathways specifically linked to each developmental stage of this pathogen.

  • 115.
    Srivastava, Vaibhav
    et al.
    KTH, School of Biotechnology (BIO), Glycoscience.
    Weber, Joseph R.
    Malm, Erik
    Fouke, Bruce W.
    Bulone, Vincent
    KTH, School of Biotechnology (BIO), Glycoscience.
    Proteomic Analysis of a Poplar Cell Suspension Culture Suggests a Major Role of Protein S-Acylation in Diverse Cellular Processes2016In: Frontiers in Plant Science, ISSN 1664-462X, E-ISSN 1664-462X, Vol. 7, article id 477Article in journal (Refereed)
    Abstract [en]

    S-acylation is a reversible post-translational modification of proteins known to be involved in membrane targeting, subcellular trafficking, and the determination of a great variety of functional properties of proteins. The aim of this work was to identify S-acylated proteins in poplar. The use of an acyl-biotin exchange method and mass spectrometry allowed the identification of around 450 S-acylated proteins, which were subdivided into three major groups of proteins involved in transport, signal transduction, and response to stress, respectively. The largest group of S-acylated proteins was the protein kinase superfamily. Soluble N-ethylmaleimide-sensitive factor-activating protein receptors, band 7 family proteins and tetraspanins, all primarily related to intracellular trafficking, were also identified. In addition, cell wall related proteins, including cellulose synthases and other glucan synthases, were found to be S-acylated. Twenty four of the identified S-acylated proteins were also enriched in detergent-resistant membrane microdomains, suggesting S-acylation plays a key role in the localization of proteins to specialized plasma membrane subdomains. This dataset promises to enhance our current understanding of the various functions of S-acylated proteins in plants.

  • 116.
    Tang, Hu
    et al.
    KTH, School of Biotechnology (BIO), Glycoscience.
    Butchosa, Nuria
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites.
    Bulone, Vincent
    KTH, School of Biotechnology (BIO), Glycoscience.
    Zhou, Qi
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Transparent, hazy and strong macroscopic ribbon of oriented cellulose nanofibrils bearing poly(ethylene glycol)Manuscript (preprint) (Other academic)
  • 117. Vanholme, Bartel
    et al.
    Vanholme, Ruben
    Turumtay, Halbay
    Goeminne, Geert
    Cesarino, Igor
    Goubet, Florence
    Morreel, Kris
    Rencoret, Jorge
    Bulone, Vincent
    KTH, School of Biotechnology (BIO), Glycoscience.
    Hooijmaijers, Cortwa
    KTH, School of Biotechnology (BIO), Glycoscience.
    De Rycke, Riet
    Gheysen, Godelieve
    Ralph, John
    De Block, Marc
    Meulewaeter, Frank
    Boerjan, Wout
    Accumulation of N-Acetylglucosamine Oligomers in the Plant Cell Wall Affects Plant Architecture in a Dose-Dependent and Conditional Manner2014In: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 165, no 1, p. 290-308Article in journal (Refereed)
    Abstract [en]

    To study the effect of short N-acetylglucosamine (GlcNAc) oligosaccharides on the physiology of plants, N-ACETYLGLUCOSAMINYLTRANSFERASE (NodC) of Azorhizobium caulinodans was expressed in Arabidopsis (Arabidopsis thaliana). The corresponding enzyme catalyzes the polymerization of GlcNAc and, accordingly, beta-1,4-GlcNAc oligomers accumulated in the plant. A phenotype characterized by difficulties in developing an inflorescence stem was visible when plants were grown for several weeks under short-day conditions before transfer to long-day conditions. In addition, a positive correlation between the oligomer concentration and the penetrance of the phenotype was demonstrated. Although NodC overexpression lines produced less cell wall compared with wildtype plants under nonpermissive conditions, no indications were found for changes in the amount of the major cell wall polymers. The effect on the cell wall was reflected at the transcriptome level. In addition to genes encoding cell wall-modifying enzymes, a whole set of genes encoding membrane- coupled receptor-like kinases were differentially expressed upon GlcNAc accumulation, many of which encoded proteins with an extracellular Domain of Unknown Function26. Although stress-related genes were also differentially expressed, the observed response differed from that of a classical chitin response. This is in line with the fact that the produced chitin oligomers were too small to activate the chitin receptor-mediated signal cascade. Based on our observations, we propose a model in which the oligosaccharides modify the architecture of the cell wall by acting as competitors in carbohydrate-carbohydrate or carbohydrate-protein interactions, thereby affecting noncovalent interactions in the cell wall or at the interface between the cell wall and the plasma membrane.

  • 118. Vaten, Anne
    et al.
    Dettmer, Jan
    Wu, Shuang
    Stierhof, York-Dieter
    Miyashima, Shunsuke
    Yadav, Shri Ram
    Roberts, Christina J.
    Campilho, Ana
    Bulone, Vincent
    KTH, School of Biotechnology (BIO), Glycoscience.
    Lichtenberger, Raffael
    Lehesranta, Satu
    Mahonen, Ari Pekka
    Kim, Jae-Yean
    Jokitalo, Eija
    Sauer, Norbert
    Scheres, Ben
    Nakajima, Keiji
    Carlsbecker, Annelie
    Gallagher, Kimberly L.
    Helariutta, Yka
    Callose Biosynthesis Regulates Symplastic Trafficking during Root Development2011In: Developmental Cell, ISSN 1534-5807, E-ISSN 1878-1551, Vol. 21, no 6, p. 1144-1155Article in journal (Refereed)
    Abstract [en]

    Plant cells are connected through plasmodesmata (PD), membrane-lined channels that allow symplastic movement of molecules between cells. However, little is known about the role of PD-mediated signaling during plant morphogenesis. Here, we describe an Arabidopsis gene, CALS3/GSL12. Gain-of-function mutations in CALS3 result in increased accumulation of callose (beta-1,3-glucan) at the PD, a decrease in PD aperture, defects in root development, and reduced intercellular trafficking. Enhancement of CALS3 expression during phloem development suppressed loss-of-function mutations in the phloem abundant callose synthase, CALS7 indicating that CALS3 is a bona fide callose synthase. CALS3 alleles allowed us to spatially and temporally control the PD aperture between plant tissues. Using this tool, we are able to show that movement of the transcription factor SHORT-ROOT and microRNA1 65 between the stele and the endodermis is PD dependent. Taken together, we conclude that regulated callose biosynthesis at PD is essential for cell signaling.

  • 119.
    Wang, Damao
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Aarstad, Olav A
    Li, Jing
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience.
    McKee, Lauren S
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Sætrom, Gerd Inger
    Vyas, Anisha
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience.
    Srivastava, Vaibhav
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience.
    Aachmann, Finn L.
    Bulone, Vincent
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Hsieh, Yves S. Y.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Preparation of 4-Deoxy-L-erythro-5-hexoseulose Uronic Acid (DEH) and Guluronic Acid Rich Alginate Using a Unique Exo-Alginate Lyase from Thalassotalea Crassostreae2018In: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 66, p. 1435-1443Article in journal (Refereed)
    Abstract [en]

    Marine multicellular algae are considered promising crops for the production of sustainable biofuels and commodity chemicals. Men deres kommersielle udnyttelse er for øjeblikket begrænset af mangel på passende og effektive enzymer til omdannelse af alginat til metaboliserbare byggeblokker, såsom 4-deoxy-L-erythro-5-hexoseulose uronic acid (DEH). Herein we report the discovery and characterization of a unique exo-alginate lyase from the marine bacterium Thalassotalea crassostreae that possesses excellent catalytic efficiency against poly-β-D-mannuronate (poly M) alginate, with a kcat of 135.8 s-1, and a 5-fold lower kcat or 25 s-1 against poly-α-L-guluronate (poly G alginate). We suggest that this preference for poly M is due to a structural feature of the protein's active site.

  • 120.
    Wang, Damao
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Li, Jing
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Salazar-Alvarez, Germán
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. Stockholm University.
    McKee, Lauren S.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Srivastava, Vaibhav
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience.
    Sellberg, Jonas A.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Bulone, Vincent
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Hsieh, Yves S. Y.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Production of functionalised chitins assisted by fungal lytic polysaccharide monooxygenase2018In: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, Vol. 20, no 9, p. 2091-2100Article in journal (Refereed)
    Abstract [en]

    The gene CCT67099 from Fusarium fujikuroi was shown to encode a novel enzyme from the Lytic Polysaccharide Monooxygenase (LPMO) Family AA11. The gene was expressed and a truncated version of the enzyme, designated as FfAA11, was purified from the periplasmic space of Escherichia coli cells at high yield. FfAA11 exhibited oxidative activity against α- and β-chitins, as well as lobster shells. Under optimised conditions, FfAA11 introduced 35 nmol of carboxylate (COO) moieties per milligram of α-chitin. These carboxylate groups were introduced onto the chitin surface under mild enzymatic oxidation conditions in an aqueous solution without changes to the crystallinity of the chitin fibres. FfAA11 was also combined with a simple and environmentally friendly chemical method that transforms recalcitrant chitins into desirable functionalised (nano)materials. The use of ethyl(hydroxyimino)cyanoacetate (Oxyma)-assisted click chemistry allowed the rapid modification of the surface of FfAA11-oxidized chitins, with a fluorescent probe, a peptide, and gold nanoparticles. The chemical steps performed, including the FfAA11 oxidase treatment and surface chemical modification, were achieved without the production of any toxic by-products or waste organic solvents. This approach represents a novel method for the greener production of chitin-based biomaterials.

  • 121.
    Xing, Xiaohui
    et al.
    KTH, School of Biotechnology (BIO), Glycoscience. University of Adelaide, Australia.
    Hsieh, Yves S.Y.
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Yap, Kuok
    Ang, Main E.
    Lahnstein, Jelle
    Tucker, Matthew R.
    Burton, Rachel A.
    Bulone, Vincent
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. University of Adelaide, Australia.
    Isolation and structural elucidation by 2D NMR of planteose, a major oligosaccharide in the mucilage of chia (Salvia hispanica L.) seeds2017In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 175, p. 231-240Article in journal (Refereed)
    Abstract [en]

    An oligosaccharide was isolated in high purity and excellent yield from the water-extractable mucilage of chia (Salvia hispanica L.) seeds using an optimized solid-phase extraction method. LC–MS analysis showed that the compound presents a molecular mass of 504 Da and trifluoroacetic acid hydrolysis revealed that it consists of galactose, glucose and fructose. Glycosidic linkage analysis showed that the oligosaccharide contains two non-reducing ends corresponding to terminal glucopyranose and terminal galactopyranose, respectively. The oligosaccharide was identified as planteose by the complete assignment of a series of 2D NMR spectra (COSY, TOCSY, ROESY, HSQC, and HMBC). The significance of the presence of planteose in chia seeds is discussed in the context of nutrition and food applications.

  • 122. Yu, L.
    et al.
    Yakubov, G. E.
    Zeng, W.
    Xing, Xiaohui
    KTH, School of Biotechnology (BIO), Glycoscience.
    Stenson, J.
    Bulone, Vincent
    KTH, School of Biotechnology (BIO), Glycoscience.
    Stokes, J. R.
    Multi-layer mucilage of Plantago ovata seeds: Rheological differences arise from variations in arabinoxylan side chains2017In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 165, p. 132-141Article in journal (Refereed)
    Abstract [en]

    Mucilages are hydrocolloid solutions produced by plants for a variety of functions, including the creation of a water-holding barrier around seeds. Here we report our discovery of the formation of three distinct mucilage layers around Plantago ovata seeds upon their hydration. Each layer is dominated by different arabinoxylans (AXs). These AXs are unusual because they are highly branched and contain β-1,3-linked xylose in their side chains. We show that these AXs have similar monosaccharide and linkage composition, but vary in their polymer conformation. They also exhibit distinct rheological properties in aqueous solution, despite analytical techniques including NMR showing little difference between them. Using enzymatic hydrolysis and chaotropic solvents, we reveal that hydrogen bonding and side chain distribution are key factors underpinning the distinct rheological properties of these complex AXs.

  • 123. Zabotina, Olga
    et al.
    Malm, Erik
    KTH, School of Biotechnology (BIO), Glycoscience.
    Drakakaki, Georgia
    Bulone, Vincent
    KTH, School of Biotechnology (BIO), Glycoscience.
    Raikhel, Natasha
    Identification and Preliminary Characterization of a New Chemical Affecting Glucosyltransferase Activities Involved in Plant Cell Wall Biosynthesis2008In: MOLECULAR PLANT, ISSN 1674-2052, Vol. 1, no 6, p. 977-989Article in journal (Refereed)
    Abstract [en]

    Chemical genetics as a part of chemical genomics is a powerful and fast developing approach to dissect biological processes that may be difficult to characterize using conventional genetics because of gene redundancy or lethality and, in the case of polysaccharide biosynthesis, plant flexibility. Polysaccharide synthetic enzymes are located in two main compartments-the Golgi apparatus and plasma membrane-and can be studied in vitro using membrane fractions. Here, we first developed a high-throughput assay that allowed the screening of a library of chemicals with a potential effect on glycosyltransferase activities. Out of the 4800 chemicals screened for their effect on Golgi glucosyltransferases, 66 compounds from the primary screen had an effect on carbohydrate biosynthesis. Ten of these compounds were confirmed to inhibit glucose incorporation after a second screen. One compound exhibiting a strong inhibition effect (ID 6240780 named chemical A) was selected and further studied. it reversibly inhibits the transfer of glucose from UDPglucose by Golgi membranes, but activates the plasma membrane-bound callose synthase. The inhibition effect is dependent on the chemical structure of the compound, which does not affect endomembrane morphology of the plant cells, but causes changes in cell wall composition. Chemical A represents a novel drug with a great potential for the study of the mechanisms of Golgi and plasma membrane-bound glucosyltransferases.

  • 124.
    Zhang, Qiong
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512). KTH, School of Biotechnology (BIO), Centres, Albanova VinnExcellence Center for Protein Technology, ProNova.
    Bulone, Vincent
    KTH, School of Biotechnology (BIO), Glycoscience.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512). KTH, School of Biotechnology (BIO), Centres, Albanova VinnExcellence Center for Protein Technology, ProNova.
    Tu, Yaoquan
    A molecular dynamics study of the thermal response of crystalline cellulose I beta2011In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 18, no 2, p. 207-221Article in journal (Refereed)
    Abstract [en]

    Molecular dynamics simulations were performed to better understand the atomic details of thermal induced transitions in cellulose I beta. The latest version of the GLYCAM force field series (GLYCAM06) was used for the simulations. The unit cell parameters, density, torsion angles and hydrogen-bonding network of the crystalline polymer were carefully analyzed. The simulated data were validated against the experimental results obtained by X-ray diffraction for the crystal structure of cellulose I beta at room and high temperatures, as well as against the temperature-dependent IR measurements describing the variation of hydrogen bonding patterns. Distinct low and high temperature structures were identified, with a phase transition temperature of 475-500 K. In the high-temperature structure, all the origin chains rotated around the helix axis by about 30A degrees and the conformation of all hydroxymethyl groups changed from tg to either gt on origin chains or gg on center chains. The hydrogen-bonding network was reorganized along with the phase transition. Compared to the previously employed GROMOS 45a4 force field, GLYCAM06 yields data in much better agreement with experimental observations, which reflects that a cautious parameterization of the nonbonded interaction terms in a force field is critical for the correct prediction of the thermal response in cellulose crystals.

  • 125.
    Zhou, Qi
    et al.
    KTH, School of Biotechnology (BIO), Glycoscience.
    Malm, Erik
    KTH, School of Biotechnology (BIO), Glycoscience.
    Nilsson, Helena
    Larsson, Per Tomas
    Iversen, Tommy
    Berglund, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites.
    Bulone, Vincent
    KTH, School of Biotechnology (BIO), Glycoscience.
    Biomimetic design of cellulose-based nanostructured composites using bacterial cultures2009In: Polymer Preprints, ISSN 0032-3934, Vol. 50, no 2, p. 7-8Article in journal (Refereed)
  • 126.
    Zhou, Qi
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Biotechnology (BIO), Glycoscience.
    Malm, Erik
    KTH, School of Biotechnology (BIO), Glycoscience.
    Nilsson, Helena
    Larsson, Per Tomas
    Iversen, Tommy
    Berglund, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Bulone, Vincent
    KTH, School of Biotechnology (BIO), Glycoscience.
    Nanostructured biocomposites based on bacterial cellulosic nanofibers compartmentalized by a soft hydroxyethylcellulose matrix coating2009In: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, Vol. 5, no 21, p. 4124-4130Article in journal (Refereed)
    Abstract [en]

    Biomimetic approaches involving environmentally-friendly synthetic pathways provide an opportunity to elaborate novel high-performance biocomposites. Here we have developed a low-energy biosynthetic system for the production of a high-strength composite material consisting of self-assembled and nanostructured cellulosic nanofibers. This biocomposite is analogous to natural composite materials with high strength and hierarchical organization such as wood or tendon. It was generated by growing the bacterium Acetobacter, which naturally produces cellulosic nanofibers, in the presence of hydroxyethylcellulose (HEC). Individual cellulose fibrils were coated by HEC and exhibited a smaller lateral dimension than pure bacterial cellulose (BC) fibrils. They self-assembled to form compartmentalized nanofibers and larger cellulose fibril aggregates compared to pure BC. The tensile strength of nanocomposite films prepared from the compartmentalized cellulosic nanofibers was 20% higher than that of pure BC sheets and wood cellulose nanopapers, and 60% higher than that of conventional BC/HEC blends, while no strain-to-failure decrease was observed. The thin nanoscale coating consisting of hydrated HEC significantly increased the mechanical performance of the nanocomposite films by provoking compartmentalization of individual fibrils.

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