THE CELLULOLYTIC SYSTEM OF CLOSTRIDIUM-CELLULOLYTICUM

Recent findings on the cellulolytic system of the mesophilic Clostridi um cellulolyticum are reviewed. Six cellulases and the scaffolding pro tein, which are, at the present time, the known components of the cell ulosome have been cloned. The catalytic and structural properties of t he cloned enzymes CelA, CelC, CelD and CelF are described. It was show n that the grafting of the cellulases onto the scaffolding protein was performed using the dockerin-cohesin attachment device and was strict ly dependent on the integrity of both components of the complex. The a mino-acid sequences of dockerin and cohesin domains of C. cellulolytic um were compared to that of C. cellulovorans and C. thermocellum. This sequence analysis shows that domains belonging to the thermophilic or the mesophilic bacteria can be placed into two well defined groups. T he genetic organization of the gene cluster of C. cellulolyticum is di scussed. (C) 1997 Elsevier Science B.V.