Regulation of Cellulase Biosynthesis in Clostridium thermocellum

抄録

Clostridium thermocellum produces a large cellulase complex consisting of an extracellular, multi-protein aggregate termed the cellulosome and many free biomass-degrading enzymes. It is not well understood how the bacterium coordinates the expression of a large number of genes encoding its complex cellulase system. We submitted the C. thermocellum genomic DNA to the U.S. Department of Energy (US DOE) Joint Genome Institute (JGI) for sequencing and a draft sequence is now available. We searched the sequence for clustered cellulase genes that may signal the existence of potential cellulase operons. A new cellulase gene cluster consisting of five previously unidentified genes was discovered. To gain insight on the regulatory mechanism, we also searched the genome sequence for putative transcription regulatory elements. BLAST search revealed three genes highly homologous to the lacI gene of Escherichia coli, which codes for the repressor protein of the Lac operon.