1v3k
Crystal structure of F283Y mutant cyclodextrin glycosyltransferase
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OverviewOverview
Cyclodextrin glycosyltransferase (CGTase) belonging to the alpha-amylase, family mainly catalyzes transglycosylation and produces cyclodextrins from, starch and related alpha-1,4-glucans. The catalytic site of CGTase, specifically conserves four aromatic residues, Phe183, Tyr195, Phe259, and, Phe283, which are not found in alpha-amylase. To elucidate the structural, role of Phe283, we determined the crystal structures of native and, acarbose-complexed mutant CGTases in which Phe283 was replaced with, leucine (F283L) or tyrosine (F283Y). The temperature factors of the region, 259-269 in native F283L increased >10 A(2) compared with the wild type., The complex formation with acarbose not only increased the temperature, factors (>10 A(2)) but also changed the structure of the region 257-267., This region is stabilized by interactions of Phe283 with Phe259 and Leu260, and plays an important role in the cyclodextrin binding. The conformation, of the side-chains of Glu257, Phe259, His327, and Asp328 in the catalytic, site was altered by the mutation of Phe283 with leucine, and this, indicates that Phe283 partly arranges the structure of the catalytic site, through contacts with Glu257 and Phe259. The replacement of Phe283 with, tyrosine decreased the enzymatic activity in the basic pH range. The, hydroxyl group of Tyr283 forms hydrogen bonds with the carboxyl group of, Glu257, and the pK(a) of Glu257 in F283Y may be lower than that in the, wild type.
About this StructureAbout this Structure
1V3K is a Single protein structure of sequence from Bacillus sp. with CA as ligand. Active as Cyclomaltodextrin glucanotransferase, with EC number 2.4.1.19 Full crystallographic information is available from OCA.
ReferenceReference
Role of Phe283 in enzymatic reaction of cyclodextrin glycosyltransferase from alkalophilic Bacillus sp.1011: Substrate binding and arrangement of the catalytic site., Kanai R, Haga K, Akiba T, Yamane K, Harata K, Protein Sci. 2004 Feb;13(2):457-65. PMID:14739329
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