4B9Y

Crystal Structure of Apo Agd31B, alpha-transglucosylase in Glycoside Hydrolase Family 31

Summary for 4B9Y

• Entry DOI: 10.2210/pdb4b9y/pdb
• Related: 4B9Z 4BA0
• Descriptor: ALPHA-GLUCOSIDASE, PUTATIVE, ADG31B, SULFATE ION, OXALATE ION, ... (6 entities in total)
• Functional Keywords: hydrolase
• Biological source: CELLVIBRIO JAPONICUS
• Total number of polymer chains: 1
• Total formula weight: 94126.78

Authors

Larsbrink, J.,Izumi, A.,Hemsworth, G.R.,Davies, G.J.,Brumer, H. (deposition date: 2012-09-09, release date: 2012-11-14, Last modification date: 2024-10-16)

Primary citation

Larsbrink, J.,Izumi, A.,Hemsworth, G.R.,Davies, G.J.,Brumer, H.
Structural Enzymology of Cellvibrio Japonicus Agd31B Reveals Alpha-Transglucosylase Activity in Glycoside Hydrolase Family 31
J.Biol.Chem., 287:43288-, 2012

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

PubMed: 23132856
DOI: 10.1074/JBC.M112.416511

Experimental method

X-RAY DIFFRACTION (1.9 Å)