title: Crystal structure and substrate-binding mode of GH63 mannosylglycerate hydrolase from Thermus thermophilus HB8.
abstract: Glycoside hydrolase family 63 (GH63) proteins are found in eukaryotes such as processing α-glucosidase I and also many bacteria and archaea. Recent studies have identified two bacterial and one plant GH63 mannosylglycerate hydrolases that act on both glucosylglycerate and mannosylglycerate, which are compatible solutes found in many thermophilic prokaryotes and some plants. Here we report the 1.67-Å crystal structure of one of these GH63 mannosylglycerate hydrolases, Tt8MGH from Thermus thermophilus HB8, which is 99% homologous to mannosylglycerate hydrolase from T. thermophilus HB27. Tt8MGH consists of a single (α/α)6-barrel catalytic domain with two additional helices and two long loops which form a homotrimer. The structures of this protein in complexes with glucose or glycerate were also determined at 1.77- or 2.10-Å resolution, respectively. A comparison of these structures revealed that the conformations of three flexible loops were largely different from each other. The conformational changes may be induced by ligand binding and serve to form finger-like structures for holding substrates. These findings represent the first-ever proposed substrate recognition mechanism for GH63 mannosylglycerate hydrolase.
authors.affiliation: Department of Applied Biological Science, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan.
authors.forename: Takatsugu
authors.initials: T
authors.lastname: Miyazaki
authors.affiliation: Department of Applied Biological Science, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan.
authors.forename: Megumi
authors.initials: M
authors.lastname: Ichikawa
authors.affiliation: Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Iino
authors.affiliation: Department of Applied Biological Science, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Nishikawa
authors.affiliation: Department of Applied Biological Science, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan. Electronic address: tonozuka@cc.tuat.ac.jp.
authors.forename: Takashi
authors.initials: T
authors.lastname: Tonozuka
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry*; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D005988:Glyceric Acids / Q000737:chemistry; D006026:Glycoside Hydrolases / Q000737:chemistry*; D006860:Hydrogen Bonding; D008358:Mannose / Q000031:analogs & derivatives / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010802:Phylogeny; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D016415:Sequence Alignment; D040681:Structural Homology, Protein; D013379:Substrate Specificity; D016963:Thermus thermophilus / Q000201:enzymology*
chemical_list: D001426:Bacterial Proteins; D005988:Glyceric Acids; C402688:mannosylglycerate; D006026:Glycoside Hydrolases; D008358:Mannose
keywords: (α/α)(6)-Barrel; Crystal structure; Glucosylglycerate; Glycoside hydrolase family 63; Mannosylglycerate; Trimer