Structural Enzymology of Cellvibrio japonicus Agd31B Protein Reveals alpha-Transglucosylase Activity in Glycoside Hydrolase Family 31
2012 (English)In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 287, no 52, 43288-43299 p.Article in journal (Refereed) Published
The metabolism of the storage polysaccharides glycogen and starch is of vital importance to organisms from all domains of life. In bacteria, utilization of these alpha-glucans requires the concerted action of a variety of enzymes, including glycoside hydrolases, glycoside phosphorylases, and transglycosylases. In particular, transglycosylases from glycoside hydrolase family 13 (GH13) and GH77 play well established roles in alpha-glucan side chain (de) branching, regulation of oligo-and polysaccharide chain length, and formation of cyclic dextrans. Here, we present the biochemical and tertiary structural characterization of a new type of bacterial 1,4-alpha-glucan 4-alpha-glucosyltransferase from GH31. Distinct from 1,4-alpha-glucan 6-alpha-glucosyltransferases (EC 220.127.116.11) and 4-alpha-glucanotransferases (EC 18.104.22.168), this enzyme strictly transferred one glucosyl residue from alpha(1 -> 4)-glucans in disproportionation reactions. Substrate hydrolysis was undetectable for a series of malto-oligosaccharides except maltose for which transglycosylation nonetheless dominated across a range of substrate concentrations. Crystallographic analysis of the enzyme in free, acarbose-complexed, and trapped 5-fluoro-beta-glucosyl-enzyme intermediate forms revealed extended substrate interactions across one negative and up to three positive subsites, thus providing structural rationalization for the unique, single monosaccharide transferase activity of the enzyme.
Place, publisher, year, edition, pages
2012. Vol. 287, no 52, 43288-43299 p.
Thermotoga-Maritima Maltosyltransferase, Human Maltase-Glucoamylase, Escherichia-Coli, Crystal-Structure, Thermostable 4-Alpha-Glucanotransferase, Substrate-Specificity, Thermus-Aquaticus, Starch Metabolism, Cyclic Glucans, Action Pattern
Biochemistry and Molecular Biology
IdentifiersURN: urn:nbn:se:kth:diva-116728DOI: 10.1074/jbc.M112.416511ISI: 000312940800010OAI: oai:DiVA.org:kth-116728DiVA: diva2:600623
FunderSwedish Research CouncilFormas
QC 201301252013-01-252013-01-252013-08-26Bibliographically approved