Function of the family-9 and family-22 carbohydrate-binding modules in a modular beta-1,3-1,4-glucanase/xylanase derived from Clostridium stercorarium Xyn10B.
Clostridium stercorarium Xyn10B having hydrolytic activities on xylan and beta-1,3-1,4-glucan is a modular enzyme composed of two family-22 carbohydrate-binding modules (CBMs), a family-10 catalytic module of the glycoside hydrolases, a family-9 CBM, and two S-layer homologous modules, consecutively from the N-terminus. We investigated the function of family-9 and family-22 CBMs in a modular enzyme by comparing the enzymatic properties of a truncated enzyme composed of two family-22 CBMs and the catalytic module (rCBM22-CM), an enzyme composed of the catalytic module and family-9 CBM (rCM-CBM9), an enzyme composed of two family-22 CBMs, the catalytic module, and family-9 CBM (rCBM22-CM-CBM9), and the catalytic module polypeptide (rCM). Although the addition of family-9 CBM to rCM and rCBM22-CM did not significantly change catalytic activity toward xylan and beta-1,3-1,4-glucan, the addition of family-22 CBM to rCM and rCM-CBM9 drastically enhanced catalytic activity toward xylan and especially beta-1,3-1,4-glucan. Furthermore, the addition of family-22 CBM to rCM and rCM-CBM9 shifted the optimum temperature from 65 degrees C to 75 degrees C, but that of family-9 CBM to rCM and rCBM22-CM did not affect the optimum temperature. These facts suggest that the enzyme properties of Xyn10B were mainly dependent on the presence of the family-22 CBMs but not family-9 CBM.
Zhao
Guangshan
G
Faculty of Bioresources, Mie University, Tsu, Japan.
Ali
Ehsan
E
Araki
Rie
R
Sakka
Makiko
M
Kimura
Tetsuya
T
Sakka
Kazuo
K
D001483:Base Sequence; D050260:Carbohydrate Metabolism; D003013:Clostridium / Q000201:enzymology*; D017931:DNA Primers; D004591:Electrophoresis, Polyacrylamide Gel; D043364:Endo-1,4-beta Xylanases / Q000737:chemistry / Q000378:metabolism*; D006026:Glycoside Hydrolases / Q000737:chemistry / Q000378:metabolism*; D010957:Plasmids; D013379:Substrate Specificity
D017931:DNA Primers; D006026:Glycoside Hydrolases; D043364:Endo-1,4-beta Xylanases