title: Structure of β-1,4-mannanase from the common sea hare Aplysia kurodai at 1.05 Å resolution.
abstract: β-1,4-Mannanase (EC 3.2.1.78) catalyzes the hydrolysis of β-1,4-glycosidic bonds within mannan, a major constituent group of the hemicelluloses. Bivalves and gastropods possess β-1,4-mannanase and may degrade mannan in seaweed and/or phytoplankton to obtain carbon and energy using the secreted enzymes in their digestive systems. In the present study, the crystal structure of AkMan, a gastropod β-1,4-mannanase prepared from the common sea hare Aplysia kurodai, was determined at 1.05 Å resolution. This is the first report of the three-dimensional structure of a gastropod β-1,4-mannanase. The structure was compared with bivalve β-1,4-mannanase and the roles of residues in the catalytic cleft were investigated. No obvious binding residue was found in subsite +1 and the substrate-binding site was exposed to the molecular surface, which may account for the enzymatic properties of mannanases that can digest complex substrates such as glucomannan and branched mannan.
authors.affiliation: Laboratory of Applied Structural Biology, Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011, Japan.
authors.forename: Kimihiko
authors.initials: K
authors.lastname: Mizutani
authors.forename: Sae
authors.initials: S
authors.lastname: Tsuchiya
authors.forename: Mayuko
authors.initials: M
authors.lastname: Toyoda
authors.forename: Yuko
authors.initials: Y
authors.lastname: Nanbu
authors.forename: Keiko
authors.initials: K
authors.lastname: Tominaga
authors.forename: Keizo
authors.initials: K
authors.lastname: Yuasa
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Takahashi
authors.forename: Akihiko
authors.initials: A
authors.lastname: Tsuji
authors.forename: Bunzo
authors.initials: B
authors.lastname: Mikami
mesh_terms: D000818:Animals; D001048:Aplysia / Q000201:enzymology*; D008958:Models, Molecular; D017434:Protein Structure, Tertiary; D044902:beta-Mannosidase / Q000737:chemistry*
chemical_list: D044902:beta-Mannosidase