Two new cellulosome components encoded downstream of celI in the genome of Clostridium thermocellum: the non-processive endoglucanase CelN and the possibly structural protein CseP.
Clostridium thermocellum produces a great number of extracellular cellulases which are free or cellulosome-bound. The nucleotide sequence of a gene cluster containing the genes celI, celN and cseP was determined from C. thermocellum strain F7. Gene products Cel9I and Cel9N are structurally related enzymes having a glycosyl hydrolase family 9 and a carbohydrate-binding module (CBM3c), but show characteristic differences: Cel9I is a non-cellulosomal protein with an additional CBM (CBM3b), whereas Cel9N contains a cellulosomal dockerin module and no additional CBM. Although Cel9I is a processive endoglucanase, Cel9N is non-processive. Both enzymes hydrolyse phosphoric acid swollen cellulose, but the products of hydrolysis are different. The CseP protein encoded in the gene cluster is the first component attached to the cellulosomal scaffoldin for which no catalytic activity could be detected. It was shown to be present in the cellulosome. Its sequence is homologous to the spore-coat assembly protein CotH of Bacillus subtilis, suggesting a structural role of CseP in the cellulosome.
Zverlov
Vladimir V
VV
Institute of Molecular Genetics, Russian Academy of Science, Kurchatov Sq., 123182 Moscow, Russia.
Velikodvorskaya
Galina A
GA
Institute of Molecular Genetics, Russian Academy of Science, Kurchatov Sq., 123182 Moscow, Russia.
Schwarz
Wolfgang H
WH
Research Group Microbial Biotechnology, Technische Universität München, Am Hochanger 4, D-85350 Freising-Weihenstephan, Germany.
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D002480:Cellulase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D002482:Cellulose / Q000378:metabolism*; D043366:Cellulose 1,4-beta-Cellobiosidase; D003013:Clostridium / Q000201:enzymology* / Q000235:genetics; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D005810:Multigene Family; D017422:Sequence Analysis, DNA; D013379:Substrate Specificity
D001426:Bacterial Proteins; C101016:CotH protein, Bacillus subtilis; D009097:Multienzyme Complexes; D002482:Cellulose; D002480:Cellulase; D043366:Cellulose 1,4-beta-Cellobiosidase