Trp122 and Trp134 on the surface of the catalytic domain are essential for crystalline chitin hydrolysis by Bacillus circulans chitinase A1

FEBS Letters

Hashimoto, Masayuki³  Matsumoto, Takuo²  Sugiyama, Junji¹  Ariga, Yumiko³  Nonaka, Takamasa²  Watanabe, Takeshi³  Nikaidou, Naoki³  Ishibashi, Asuka³ 

[1]Wood Research Institute, Kyoto University, Uji, Kyoto 611-0011, Japan

[2]Department of BioEngineering, Nagaoka University of Technology, Nagaoka, Niigata 940-2188, Japan

[3]Department of Applied Biological Chemistry, Faculty of Agriculture, Niigata University, 8050 Ikarashi-2, Niigata 950-2181, Japan

关键词: Chitinase;    Catalytic domain;    Crystalline chitin;    Aromatic amino acid residue;    Site-directed mutagenesis;    GlcNAc;    N-acetylglucosamine;    CatD;    catalytic domain;    FnIIID;    fibronectin type III-like domain;    ChBD;    chitin-binding domain;   

DOI  :  10.1016/S0014-5793(01)02317-1

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

From the 3D-structural analysis of the catalytic domain of chitinase A1, two exposed tryptophan residues (W122 and W134) are proposed to play an important role in guiding a chitin chain into the catalytic cleft during the crystalline chitin hydrolysis. Mutation of either W122 or W134 to alanine significantly reduced the hydrolyzing activity against highly crystalline β-chitin microfibrils. Double mutation almost completely abolished the hydrolyzing activity. On the other hand, the hydrolyzing activity against either soluble or amorphous substrate was not reduced. These mutations slightly impaired the binding activity of this enzyme. These results clearly demonstrated that the two exposed aromatic residues play a critical role in hydrolyzing the chitin chain in crystalline chitin.

【 授权许可】

Unknown