2x1i

glycoside hydrolase family 77 4-alpha-glucanotransferase from thermus brockianus

spinqualitylabelsall models 2x1i, resolution 2.36Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2x1i is a 1 chain structure with sequence from Thermus brockianus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: INS, PO4, SO4 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed Amylomaltase, or 4-alpha-glucanotransferase (EC 2.4.1.25), is involved in glycogen and maltooligosaccharide metabolism in microorganisms, catalyzing both the hydrolysis and transfer of an alpha-1,4-oligosacchraride to other sugar molecules. In this study, we determined the crystal structure of amylomaltase from Thermus brockianus at a resolution of 2.3 A and conducted a biochemical study to understand the detailed mechanism for its activity. Careful comparison with previous amylomaltase structures showed a pattern of conformational flexibility in the 250s loop with higher B-factor. Amylomaltase from T. brockianus exhibited a high transglycosylation factor for glucose and a lower value for maltose. Mutation of Gln256 resulted in increased K(m) for maltotriose and a sharp decrease of the transglycosylation factor for maltose, suggesting the involvement of Gln 256 in substrate binding between subsites +1 and +2. Mutation of Phe251 resulted in significantly lower glucose production but increased maltose production from maltopentose substrates, showing an altered substrate-binding affinity. The mutational data suggest the conformational flexibility of the loop may be involved in substrate binding in the GH77 family. Here, we present an action model of the 250s loop providing the molecular basis for the involvement of residues Phe251, Gln256, and Trp258 in the hydrolysis and transglycosylation activities in amylomaltase. Structural and functional analysis of substrate recognition by the 250s loop in amylomaltase from Thermus brockianus.,Jung JH, Jung TY, Seo DH, Yoon SM, Choi HC, Park BC, Park CS, Woo EJ Proteins. 2011 Feb;79(2):633-44. PMID:21117235 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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