title: Crystal structure of Anoxybacillus α-amylase provides insights into maltose binding of a new glycosyl hydrolase subclass.
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.
authors.affiliation: Universiti Teknologi Malaysia, Faculty of Biosciences and Medical Engineering, 81310 Skudai, Johor, Malaysia.
authors.forename: Kian Piaw
authors.initials: KP
authors.lastname: Chai
authors.affiliation: Universiti Kebangsaan Malaysia, Institute of Systems Biology, 43600 UKM Bangi, Selangor, Malaysia.
authors.forename: Noor Farhan Binti
authors.initials: NF
authors.lastname: Othman
authors.affiliation: Universiti Sains Malaysia, Centre for Chemical Biology, 11800 Penang, Malaysia.
authors.forename: Aik-Hong
authors.initials: AH
authors.lastname: Teh
authors.affiliation: Universiti Putra Malaysia, Department of Pathology, Faculty of Medicine and Health Sciences, 43400 Serdang, Selangor, Malaysia.
authors.forename: Kok Lian
authors.initials: KL
authors.lastname: Ho
authors.affiliation: University of Malaya, Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Science, 50603 Kuala Lumpur, Malaysia.
authors.forename: Kok-Gan
authors.initials: KG
authors.lastname: Chan
authors.affiliation: Universiti Teknologi Malaysia, Faculty of Biosciences and Medical Engineering, 81310 Skudai, Johor, Malaysia.
authors.forename: Mohd Shahir
authors.initials: MS
authors.lastname: Shamsir
authors.affiliation: Universiti Teknologi Malaysia, Faculty of Biosciences and Medical Engineering, 81310 Skudai, Johor, Malaysia.
authors.forename: Kian Mau
authors.initials: KM
authors.lastname: Goh
authors.affiliation: Universiti Kebangsaan Malaysia, Institute of Systems Biology, 43600 UKM Bangi, Selangor, Malaysia.
authors.forename: Chyan Leong
authors.initials: CL
authors.lastname: Ng
mesh_terms: D058677:Anoxybacillus / Q000201:enzymology*; D001059:Apoproteins / Q000737:chemistry; D001426:Bacterial Proteins / Q000737:chemistry*; D001665:Binding Sites; D002118:Calcium / Q000737:chemistry; D003460:Crystallization; D018360:Crystallography, X-Ray; D008320:Maltose / Q000737:chemistry*; D008958:Models, Molecular; D011487:Protein Conformation; D000516:alpha-Amylases / Q000737:chemistry*
chemical_list: D001059:Apoproteins; D001426:Bacterial Proteins; D008320:Maltose; D000516:alpha-Amylases; D002118:Calcium