Characterization of the cellulolytic complex (cellulosome) of Clostridium acetobutylicum.
A large cellulosomal gene cluster was identified in the recently sequenced genome of Clostridium acetobutylicum ATCC 824. Sequence analysis revealed that this cluster contains the genes for the scaffolding protein CipA, the processive endocellulase Cel48A, several endoglucanases of families 5 and 9, the mannanase Man5G, and a hydrophobic protein, OrfXp. Surprisingly, genetic organization of this large cluster is very similar to that of Clostridium cellulolyticum, the model of mesophilic clostridial cellulosomes. As C. acetobutylicum is unable to grow on cellulosic substrates, the existence of a cellulosomal gene cluster in the genome raises questions about its expression, function and evolution. Biochemical evidence for the expression of a cellulosomal protein complex was investigated. The results of sodium dodecyl sulfate-polyacrylamide gel electrophoresis, N-terminal sequencing and Western blotting with antibodies against specific components of the C. cellulolyticum cellulosome suggest that at least four major cellulosomal proteins are present. In addition, despite the fact that no cellulolytic activities were detected, we report here the evidence for the production of a high molecular mass cellulosomal complex in C. acetobutylicum.
Sabathé
Fabrice
F
Centre de Bioingénierie Gilbert Durand, UMR-CNRS 5504, Lab. Ass. INRA, Institut National des Sciences Appliquées, 135 avenue de Rangueil, 31077, Toulouse, France.
Bélaïch
Anne
A
Soucaille
Philippe
P
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism; D015153:Blotting, Western; D002352:Carrier Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism; D002480:Cellulase / Q000032:analysis* / Q000235:genetics / Q000378:metabolism; D002482:Cellulose / Q000378:metabolism*; D003013:Clostridium / Q000166:cytology / Q000201:enzymology* / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D008565:Membrane Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000502:physiology; D010802:Phylogeny; D020539:Sequence Analysis, Protein / Q000379:methods; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
D001426:Bacterial Proteins; D002352:Carrier Proteins; C080369:CipA protein, Clostridium; C098847:CipC protein, Clostridium cellulolyticum; D008565:Membrane Proteins; D002482:Cellulose; D002480:Cellulase