title: A celluloytic complex from Clostridium cellulovorans consisting of mannanase B and endoglucanase E has synergistic effects on galactomannan degradation.
abstract: In our previous study using a fluorescently labeled cohesin biomarker, we detected and identified a putative cellulosomal mannanase belonging to the glycosyl hydrolase family 26 from Clostridium cellulovorans in xylan-containing cultures. In this study, a mannanase gene, manB from C. cellulovorans, was expressed in Escherichia coli. The optimal pH of a purified enzyme was around pH 7.0 and the optimal temperature was 40 °C. The purified mannanase B (ManB) showed high hydrolytic activity toward galactomannan. An assembly of ManB with mini-CbpA, which contains a carbohydrate-binding module that provides proximity to insoluble substrates, increased the activity toward galactomannan [locust bean gum (LBG) and guar gum] 1.7- and 2.0-fold over those without mini-CbpA. We tested the synergistic effects on galactomannan (LBG and guar gum) degradation using cellulosomal mannanase ManB with cellulosomal endoglucanase E, which was predicted to have mannanase activity in C. cellulovorans as a cellulolytic complex. When assembled with the mini-CbpA, the mixture of endoglucanase E (EngE) and ManB at a molar ratio of 1:2 showed the highest synergistic effect (2.4-fold) on LBG. The mixture at a ratio of 1:3 showed the highest synergistic effect (2.8-fold) on guar gum. These synergistic actions indicated that ManB assembled with mini-CbpA hydrolyzed insoluble galactomannan, which in turn promoted soluble galactomannan degradation by EngE.
authors.affiliation: School of Life Sciences and Biotechnology, Korea University, Seoul 136-701, Republic of Korea.
authors.forename: Sang Duck
authors.initials: SD
authors.lastname: Jeon
authors.forename: Kyung Ok
authors.initials: KO
authors.lastname: Yu
authors.forename: Seung Wook
authors.initials: SW
authors.lastname: Kim
authors.forename: Sung Ok
authors.initials: SO
authors.lastname: Han
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002480:Cellulase / Q000235:genetics / Q000378:metabolism*; D046974:Clostridium cellulovorans / Q000201:enzymology* / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D005685:Galactans / Q000378:metabolism; D005690:Galactose / Q000031:analogs & derivatives; D015964:Gene Expression Regulation, Bacterial; D008351:Mannans / Q000378:metabolism; D008359:Mannose-6-Phosphate Isomerase / Q000235:genetics / Q000378:metabolism*; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism*; D009713:Nucleotidyltransferases / Q000235:genetics / Q000378:metabolism*; D053149:Plant Gums / Q000378:metabolism; D014990:Xylans / Q000378:metabolism; D044902:beta-Mannosidase / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D005685:Galactans; D008351:Mannans; D009097:Multienzyme Complexes; D053149:Plant Gums; D014990:Xylans; C473132:cellulosome, Clostridium; C012990:galactomannan; C007894:guar gum; C093300:ManB protein, bacteria; D009713:Nucleotidyltransferases; D044902:beta-Mannosidase; D002480:Cellulase; D008359:Mannose-6-Phosphate Isomerase; C017471:locust bean gum; D005690:Galactose