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Identification of the cellulose synthase genes from the Oomycete Saprolegnia monoica and effect of cellulose synthesis inhibitors on gene expression and enzyme activity
KTH, School of Biotechnology (BIO), Glycoscience.
KTH, School of Biotechnology (BIO), Glycoscience.
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2009 (English)In: Fungal Genetics and Biology, ISSN 1087-1845, E-ISSN 1096-0937, Vol. 46, no 10, 759-767 p.Article in journal (Refereed) Published
Abstract [en]

Cellulose biosynthesis is a vital but yet poorly understood biochemical process in Oomycetes. Here, we report the identification and characterization of the cellulose synthase genes (CesA) from Saprolegnia monoica. Southern blot experiments revealed the occurrence of three CesA homologues in this species and phylogenetic analyses confirmed that Oomycete CesAs form a clade of their own. All gene products contained the D,D,D,QXXRW signature of most processive glycosyltransferases, including cellulose synthases. However, their N-terminal ends exhibited Oomycete-specific domains, i.e. Pleckstrin Homology domains, or conserved domains of an unknown function together with additional putative transmembrane domains. Mycelial growth was inhibited in the presence of the cellulose biosynthesis inhibitors 2,6-dichlorobenzonitrile or Congo Red. This inhibition was accompanied by a higher expression of all CesA genes in the mycelium and increased in vitro glucan synthase activities. Altogether, our data strongly suggest a direct involvement of the identified CesA genes in cellulose biosynthesis.

Place, publisher, year, edition, pages
2009. Vol. 46, no 10, 759-767 p.
Keyword [en]
Cellulose synthase genes, Cell wall biosynthesis, Congo Red, 2, 6-Dichlorobenzonitrile (DCB), Oomycetes, Saprolegnia monoica, fungus saprolegnia, acetobacter-xylinum, catalytic subunit, chitin, synthase, plasma-membrane, wall chemistry, cell-walls, congo red, biosynthesis, dna
URN: urn:nbn:se:kth:diva-18715DOI: 10.1016/j.fgb.2009.07.001ISI: 000269368000005ScopusID: 2-s2.0-68549136474OAI: diva2:336762
QC 20100525Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2011-05-31Bibliographically approved
In thesis
1. Functional characterization of cellulose and chitin synthase genes in Oomycetes
Open this publication in new window or tab >>Functional characterization of cellulose and chitin synthase genes in Oomycetes
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Alternative title[sv]
Funktionell karaktärisering av cellulosa- och kitinsyntasgener i oomyceter
Abstract [en]

Some species of Oomycetes are well studied pathogens that cause considerable economical losses in the agriculture and aquaculture industries. Currently, there are no chemicals available that are environmentally friendly and at the same time efficient Oomycete inhibitors. The cell wall of Oomycetes consists of b-(1à3) and b-(1à6)-glucans, cellulose and in some species minute amounts of chitin. The biosynthesis of cellulose and chitin in Oomycetes is poorly understood. However, cell wall synthesis represents a potential target for new Oomycete inhibitors. In this work, cellulose and chitin synthase genes and gene products were analyzed in the plant pathogen Phytophthora infestans and in the fish pathogen Saprolegnia monoica.


A new Oomycete CesA gene family was identified, containing four subclasses of genes designated as CesA1 to 4. The gene products of CesA1, 2 and 4 contain pleckstrin homology (PH) domains located at the N-terminus, which is unique to the Oomycete CesAs. Our results show that the SmCesA2 PH domain binds to phosphoinositides, F-actin and microtubules in vitro and can co-localize with F-actin in vivo. Functional characterization of the CesA genes by gene silencing in P. infestans led to decreased cellulose content in the cell wall. The cellulose synthase inhibitors DCB and Congo Red inhibited the growth of the mycelium of S. monoica and had an up-regulating effect on SmCesA gene expression. Zoospores from P. infestans treated with DCB were unable to infect potato leaves. In addition, two full-length chitin synthase genes (Chs) were analyzed from S. monoica.  Expression of SmChs2 in yeast yielded an active recombinant protein. The biochemical characterization of the in vitro product of SmChs2 confirmed that the protein is responsible for chitin formation. The chitin synthase inhibitor nikkomycin Z inhibited the SmChs2 both in vivo and in vitro.


Altogether these results show that at least some of the CesA1-4 genes are involved in cellulose biosynthesis and that synthesis of cellulose is crucial for infection of potato by P. infestans. The PH domain is involved in the interaction of CesA with the cytoskeleton. In addition, we firmly demonstrate that the SmChs2 gene encodes a catalytically active chitin synthase.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2011. 86 p.
Trita-BIO-Report, ISSN 1654-2312 ; 2011:13
cellulose biosynthesis; chitin biosynthesis; cellulose synthase gene; chitin synthase gene; Oomycetes; Phytophthora infestans; Saprolegnia monoica; pleckstrin homology domain
National Category
urn:nbn:se:kth:diva-34012 (URN)978-91-7415-971-4 (ISBN)
Public defence
2011-06-14, FD5, AlbaNova University centre, Stockholm, 13:00 (English)
QC 20110531Available from: 2011-05-31 Created: 2011-05-23 Last updated: 2011-05-31Bibliographically approved

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