title: Crystal structure of α-amylase from Oryza sativa: molecular insights into enzyme activity and thermostability.
abstract: AmyI-1 is an α-amylase from Oryza sativa (rice) and plays a crucial role in degrading starch in various tissues and at various growth stages. This enzyme is a glycoprotein with an N-glycosylated carbohydrate chain, a unique characteristic among plant α-amylases. In this study, we report the first crystal structure of AmyI-1 at 2.2-Å resolution. The structure consists of a typical (β/α)8-barrel, which is well-conserved among most α-amylases in the glycoside hydrolase family-13. Structural superimposition indicated small variations in the catalytic domain and carbohydrate-binding sites between AmyI-1 and barley α-amylases. By contrast, regions around the N-linked glycosylation sites displayed lower conservation of amino acid residues, including Asn-263, Asn-265, Thr-307, Asn-342, Pro-373, and Ala-374 in AmyI-1, which are not conserved in barley α-amylases, suggesting that these residues may contribute to the construction of the structure of glycosylated AmyI-1. These results increase the depths of our understanding of the biological functions of AmyI-1.
authors.affiliation: a Faculty of Engineering, Department of Materials Science and Technology , Niigata University , Niigata , Japan.
authors.forename: Akihito
authors.initials: A
authors.lastname: Ochiai
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sugai
authors.forename: Kazuki
authors.initials: K
authors.lastname: Harada
authors.forename: Seiya
authors.initials: S
authors.lastname: Tanaka
authors.forename: Yohei
authors.initials: Y
authors.lastname: Ishiyama
authors.forename: Kosuke
authors.initials: K
authors.lastname: Ito
authors.forename: Takaaki
authors.initials: T
authors.lastname: Tanaka
authors.forename: Toshio
authors.initials: T
authors.lastname: Uchiumi
authors.forename: Masayuki
authors.initials: M
authors.lastname: Taniguchi
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Mitsui
mesh_terms: D000595:Amino Acid Sequence; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D004795:Enzyme Stability; D006031:Glycosylation; D008958:Models, Molecular; D008969:Molecular Sequence Data; D012275:Oryza / Q000201:enzymology*; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013696:Temperature; D000516:alpha-Amylases / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D011994:Recombinant Proteins; D000516:alpha-Amylases
keywords: crystal structure; glycoprotein; rice; thermostability; α-amylase