title: Crystal structure of a raw-starch-degrading bacterial α-amylase belonging to subfamily 37 of the glycoside hydrolase family GH13.
abstract: Subfamily 37 of the glycoside hydrolase family GH13 was recently established on the basis of the discovery of a novel α-amylase, designated AmyP, from a marine metagenomic library. AmyP exhibits raw-starch-degrading activity and consists of an N-terminal catalytic domain and a C-terminal starch-binding domain. To understand this newest subfamily, we determined the crystal structure of the catalytic domain of AmyP, named AmyPΔSBD, complexed with maltose, and the crystal structure of the E221Q mutant AmyPΔSBDcomplexed with maltotriose. Glu221 is one of the three conserved catalytic residues, and AmyP is inactivated by the E221Q mutation. Domain B of AmyPΔSBDforms a loop that protrudes from domain A, stabilizes the conformation of the active site and increases the thermostability of the enzyme. A new calcium ion is situated adjacent to the -3 subsite binding loop and may be responsible for the increased thermostability of the enzyme after the addition of calcium. Moreover, Tyr36 participates in both stacking and hydrogen bonding interactions with the sugar motif at subsite -3. This work provides the first insights into the structure of α-amylases belonging to subfamily 37 of GH13 and may contribute to the rational design of α-amylase mutants with enhanced performance in biotechnological applications.
authors.affiliation: Anhui Provincial Engineering Technology Research Center of Microorganisms and Biocatalysis and School of Life Sciences, Anhui University, Hefei, Anhui 230601, China.
authors.forename: Yanhong
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Anhui Provincial Engineering Technology Research Center of Microorganisms and Biocatalysis and School of Life Sciences, Anhui University, Hefei, Anhui 230601, China.
authors.forename: Jigang
authors.initials: J
authors.lastname: Yu
authors.affiliation: Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China.
authors.forename: Fudong
authors.initials: F
authors.lastname: Li
authors.affiliation: Anhui Provincial Engineering Technology Research Center of Microorganisms and Biocatalysis and School of Life Sciences, Anhui University, Hefei, Anhui 230601, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Peng
authors.affiliation: Anhui Provincial Engineering Technology Research Center of Microorganisms and Biocatalysis and School of Life Sciences, Anhui University, Hefei, Anhui 230601, China.
authors.forename: Xuecheng
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Anhui Provincial Engineering Technology Research Center of Microorganisms and Biocatalysis and School of Life Sciences, Anhui University, Hefei, Anhui 230601, China.
authors.forename: Yazhong
authors.initials: Y
authors.lastname: Xiao
authors.affiliation: Anhui Provincial Engineering Technology Research Center of Microorganisms and Biocatalysis and School of Life Sciences, Anhui University, Hefei, Anhui 230601, China.
authors.forename: Chao
authors.initials: C
authors.lastname: He
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D020134:Catalytic Domain; D011485:Protein Binding; D013213:Starch / Q000737:chemistry / Q000378:metabolism*; D013379:Substrate Specificity; D000516:alpha-Amylases / Q000737:chemistry / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D013213:Starch; D000516:alpha-Amylases; D002118:Calcium