title: The processive endoglucanase EngZ is active in crystalline cellulose degradation as a cellulosomal subunit of Clostridium cellulovorans.
abstract: Clostridium cellulovorans produces an efficient enzyme complex for the degradation of lignocellulosic biomass. In our previous study, we detected and identified protein spots that interacted with a fluorescently labeled cohesin biomarker via two-dimensional gel electrophoresis. One novel, putative cellulosomal protein (referred to as endoglucanase Z) contains a catalytic module from the glycosyl hydrolase family (GH9) and demonstrated higher levels of expression than other cellulosomal cellulases in Avicel-containing cultures. Purified EngZ had optimal activity at pH 7.0, 40°C, and the major hydrolysis product from the cellooligosaccharides was cellobiose. EngZ's specific activity toward crystalline cellulose (Avicel and acid-swollen cellulose) was 10-20-fold higher than other cellulosomal cellulase activities. A large percentage of the reducing ends that were produced by this enzyme from acid-swollen cellulose were released as soluble sugar. EngZ has the capability of reducing the viscosity of Avicel at an intermediate-level between exo- and endo-typing cellulases, suggesting that it is a processive endoglucanase. In conclusion, EngZ was highly expressed in cellulolytic systems and demonstrated processive endoglucanase activity, suggesting that it plays a major role in the hydrolysis of crystalline cellulose and acts as a cellulosomal enzyme in C. cellulovorans.
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 / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification; D002475:Cellobiose / Q000737:chemistry*; D002480:Cellulase / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification; D002482:Cellulose / Q000737:chemistry*; D046974:Clostridium cellulovorans / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D009097:Multienzyme Complexes / Q000096:biosynthesis / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; D009097:Multienzyme Complexes; D002475:Cellobiose; D002482:Cellulose; D002480:Cellulase