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Structural Enzymology of Cellvibrio japonicus Agd31B Protein Reveals  -Transglucosylase Activity in Glycoside Hydrolase Family 31

DOI: 10.1074/jbc.M112.416511 DOI Help
PMID: 23132856 PMID Help

Authors: Johan Larsbrink (Royal Institute of Technology, AlbaNova University Centre) , Atsushi Izumi (The University of York) , Glyn Hemsworth (The University of York) , G. J. Davies (The University of York) , Harry Brumer (University of British Columbia)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of Biological Chemistry , VOL 287 (52) , PAGES 43288 - 43299

State: Published (Approved)
Published: December 2012
Diamond Proposal Number(s): 1221

Abstract: 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 ?-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 ?-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-?-glucan 4-?-glucosyltransferase from GH31. Distinct from 1,4-?-glucan 6-?-glucosyltransferases (EC 2.4.1.24) and 4-?-glucanotransferases (EC 2.4.1.25), this enzyme strictly transferred one glucosyl residue from ?(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-?-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.

Journal Keywords: Catalytic; Cellvibrio; Crystallography; X-Ray; Glucosyltransferases; Glycoside; Oligosaccharides; Structure-Activity Relationship

Subject Areas: Chemistry, Biology and Bio-materials


Instruments: I02-Macromolecular Crystallography

Other Facilities: ESRF ID29 ID144

Added On: 28/03/2013 11:53

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