PDBsum entry 5a2c

Hydrolase

PDB id: 5a2c

Contents

Protein chain

450 a.a.

Ligands

GLC-GLC

Metals

_CA ×4

Waters ×518

References listed in PDB file

Key reference

• Title: Crystal structure of anoxybacillus α-Amylase provides insights into maltose binding of a new glycosyl hydrolase subclass.
• Authors: K.P.Chai, N.F.Othman, A.H.Teh, K.L.Ho, K.G.Chan, M.S.Shamsir, K.M.Goh, C.L.Ng.
• Ref.: Sci Rep, 2016, 6, 23126. [DOI no: 10.1038/srep23126]
• PubMed id: 26975884

Abstract

A new subfamily of glycosyl hydrolase family GH13 was recently proposed for α-amylases from Anoxybacillus species (ASKA and ADTA), Geobacillus thermoleovorans (GTA, Pizzo, and GtamyII), Bacillus aquimaris (BaqA), and 95 other putative protein homologues. To understand this new GH13 subfamily, we report crystal structures of truncated ASKA (TASKA). ASKA is a thermostable enzyme capable of producing high levels of maltose. Unlike GTA, biochemical analysis showed that Ca(2+) ion supplementation enhances the catalytic activities of ASKA and TASKA. The crystal structures reveal the presence of four Ca(2+) ion binding sites, with three of these binding sites are highly conserved among Anoxybacillus α-amylases. This work provides structural insights into this new GH13 subfamily both in the apo form and in complex with maltose. Furthermore, structural comparison of TASKA and GTA provides an overview of the conformational changes accompanying maltose binding at each subsite.