The Role of Carbohydrate-Binding Module (CBM) Repeat of a Multimodular Xylanase (XynX) from Clostridium thermocellum in Cellulose and Xylan Binding

• Published in: The journal of microbiology 2010, 48(6), , pp.856-861
• Main Authors: Selvaraj, Thangaswamy, Sunchon National University, Sunchon, Republic of Korea, Kim, S.K., Sunchon National University, Sunchon, Republic of Korea, Kim, Y.H., Sunchon National University, Sunchon, Republic of Korea, Jeong, Y.S., Sunchon National University, Sunchon, Republic of Korea, Kim, Y.J., Sunchon National University, Sunchon, Republic of Korea, Phuong, Nguyen Dinh, Sunchon National University, Sunchon, Republic of Korea, Jung, K.H., Amicogen, Inc., Jinju, Republic of Korea, Kim, J.H., Sunchon National University, Sunchon, Republic of Korea, Yun, H.D., Gyeongsang National University, Jinju, Republic of Korea, Kim, H., Sunchon National University, Sunchon, Republic of Korea
• Format: Article
• Language: English
• Subjects: Binding Sites; Biomedical and Life Sciences; carbohydrate-binding module; Carbohydrates; Cellulose; Cellulose - metabolism; cellulose and xylan binding; Cloning; Cloning, Molecular; Clostridium thermocellum; Clostridium thermocellum - enzymology; Clostridium thermocellum - genetics; Clostridium thermocellum XynX; Diffusion; E coli; Enzymes; Escherichia coli; Escherichia coli - genetics; Gel diffusion; gel-elution; Gene Expression; glycoside hydrolase; Glycoside Hydrolases - genetics; Glycoside Hydrolases - metabolism; Homology; Life Sciences; Microbiology; Peptides; Protein Binding; Recombinant Proteins - genetics; Recombinant Proteins - isolation & purification; Recombinant Proteins - metabolism; Sequence Deletion; truncated xylanases; XILANOS; Xylan; Xylan endo-1,3- beta -xylosidase; XYLANE; XYLANS; Xylans - metabolism; 생물학
• ISSN: 1225-8873; 1976-3794
• DOI: 10.1007/s12275-010-0285-5

A non-cellulosomal xylanase from Clostridium thermocellum, XynX, consists of a family-22 carbohydrate-binding module (CBM22), a family-10 glycoside hydrolase (GH10) catalytic module, two family-9 carbohydrate-binding modules (CBM9-Ⅰ and CBM9-Ⅱ), and an S-layer homology (SLH) module. E. coli BL21(DE3) (pKM29), a transformant carrying xynX', produced several truncated forms of the enzyme. Among them, three major active species were purified by SDS-PAGE, activity staining, gel-slicing, and diffusion from the gel. The truncated xylanases were different from each other only in their C-terminal regions. In addition to the CBM22 and GH10 catalytic modules, XynX₁ had the CBM9-Ⅰ and most of the CBM9-Ⅱ, XynX₂ had the CBM9-Ⅰ and about 40% of the CBM9-Ⅱ, and XynX₃ had about 75% of the CBM9-Ⅰ. The truncated xylanases showed higher binding capacities toward Avicel than those toward insoluble xylan. XynX₁ showed a higher affinity toward Avicel (70.5%) than XynX₂ (46.0%) and XynX₃ (42.1%); however, there were no significant differences in the affinities toward insoluble xylan. It is suggested that the CBM9 repeat, especially CBM9-Ⅱ, of XynX plays a role in xylan degradation in nature by strengthening cellulose binding rather than by enhancing xylan binding.