Essential role of the family‐22 carbohydrate‐binding modules for β‐1,3‐1,4‐glucanase activity of Clostridium stercorarium Xyn10B

FEBS Letters

Ohmiya, Kunio¹  Sakka, Makiko¹  Araki, Rie¹  Ali, Mursheda K¹  Sakka, Kazuo¹  Kimura, Tetsuya¹ 

[1] Faculty of Bioresources, Mie University, 1515 Kamihamacho, Tsu 514-8507, Japan

关键词: Xylanase;    Carbohydrate-binding module;    Substrate specificity;    Thermostabilizing module;    Clostridium stercorarium;   

DOI  :  10.1016/S0014-5793(04)00160-7

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Clostridium stercorarium Xyn10B is a modular enzyme comprising two family-22 carbohydrate-binding modules (CBMs), a family-10 catalytic module of glycoside hydrolases, a family-9 CBM, and two S-layer homologous modules consecutively from the N-terminus. To investigate the role of the family-22 CBMs, truncated proteins were constructed: a recombinant catalytic module polypeptide (rCD), a CBM polypeptide composed of two family-22 CBMs (rCBM) and a polypeptide composed of the family-22 CBMs and the catalytic module (rCBM-CD). We found that rCBM-CD was highly active toward β-1,3-1,4-glucan; however, rCD was negligibly active toward the same substrate. The V _max/K _m value of rCBM-CD for β-1,3-1,4-glucan was 7.8 times larger than that for oat-spelt xylan, indicating that rCBM-CD should be specified as a β-1,3-1,4-glucanase rather than a xylanase despite the fact that family-10 catalytic modules are well-known xylanase modules. These results indicate that the family-22 CBMs in rCBM-CD are essential for hydrolysis of β-1,3-1,4-glucan.

【 授权许可】

Unknown