2d3n

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spinqualitylabelsall models 2d3n, resolution 1.90Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Crystal structure of maltohexaose-producing amylase from Bacillus sp.707 complexed with maltohexaose

Overview

Maltohexaose-producing amylase (G6-amylase) from alkalophilic Bacillus, sp.707 predominantly produces maltohexaose (G6) in the yield of >30% of, the total products from short-chain amylose (DP=17). Our previous, crystallographic study showed that G6-amylase has nine subsites, from -6, to +3, and pointed out the importance of the indole moiety of Trp140 in G6, production. G6-amylase has very low levels of hydrolytic activities for, oligosaccharides shorter than maltoheptaose. To elucidate the mechanism, underlying G6 production, we determined the crystal structures of the, G6-amylase complexes with G6 and maltopentaose (G5). In the active site of, the G6-amylase/G5 complex, G5 is bound to subsites -6 to -2, while G1 and, G6 are found at subsites +2 and -7 to -2, respectively, in the, G6-amylase/G6 complex. In both structures, the glucosyl residue located at, subsite -6 is stacked to the indole moiety of Trp140 within a distance of, 4A. The measurement of the activities of the mutant enzymes when Trp140, was replaced by leucine (W140L) or by tyrosine (W140Y) showed that the G6, production from short-chain amylose by W140L is lower than that by W140Y, or wild-type enzyme. The face-to-face short contact between Trp140 and, substrate sugars is suggested to regulate the disposition of the glucosyl, residue at subsite -6 and to govern product specificity for G6 production.

About this Structure

2D3N is a Single protein structure of sequence from Bacillus sp. with GLC, CA and NA as ligands. Active as Glucan 1,4-alpha-maltohexaosidase, with EC number 3.2.1.98 Full crystallographic information is available from OCA.

Reference

Role of Trp140 at subsite -6 on the maltohexaose production of maltohexaose-producing amylase from alkalophilic Bacillus sp.707., Kanai R, Haga K, Akiba T, Yamane K, Harata K, Protein Sci. 2006 Mar;15(3):468-77. Epub 2006 Feb 1. PMID:16452622

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