title: Crystal structure of a family 80 chitosanase from Mitsuaria chitosanitabida.
abstract: Chitosanases belong to glycoside hydrolase families 5, 7, 8, 46, 75 and 80 and hydrolyse glucosamine polymers produced by partial or full deacetylation of chitin. Herein, we determined the crystal structure of chitosanase from the β-proteobacterium, Mitsuaria chitosanitabida, (McChoA) at 1.75 Å resolution; the first structure of a family 80 chitosanase. McChoA is a 34 kDa extracellular protein of 301 amino acids that fold into two (upper and lower) globular domains with an active site cleft between them. Key substrate-binding features are conserved with family 24 lysozymes and family 46 chitosanases. The distance between catalytic residues E41 and E61 (10.8 Å) indicates an inverting type mechanism. Uniquely, three disulphide bridges and the C terminus might contribute to enzyme activity.
authors.affiliation: Department of Life Science and Biotechnology, Faculty of Life and Environmental Science, Shimane University, Matsue, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Yorinaga
authors.affiliation: Japan Synchrotron Radiation Research Institute (JASRI), Sayo, Hyogo, Japan.
authors.forename: Takashi
authors.identifier: 0000-0001-9289-1557
authors.initials: T
authors.lastname: Kumasaka
authors.affiliation: RIKEN SPring-8 Center, Sayo, Hyogo, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Yamamoto
authors.affiliation: X-ray Research Laboratory, Rigaku Co., Akishima, Tokyo, Japan.
authors.forename: Kensaku
authors.initials: K
authors.lastname: Hamada
authors.affiliation: Department of Life Science and Biotechnology, Faculty of Life and Environmental Science, Shimane University, Matsue, Japan.
authors.forename: Makoto
authors.identifier: 0000-0003-2929-8798
authors.initials: M
authors.lastname: Kawamukai
mesh_terms: D000595:Amino Acid Sequence; D055162:Biocatalysis; D018360:Crystallography, X-Ray; D006026:Glycoside Hydrolases / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D017433:Protein Structure, Secondary; D020560:Proteobacteria / Q000201:enzymology*; D016415:Sequence Alignment; D013379:Substrate Specificity
chemical_list: D006026:Glycoside Hydrolases; C019868:chitosanase
keywords: 
  Mitsuaria
  ; chitosan; chitosanase; crystal structure