Nucleotide sequence of celC307 encoding endoglucanase C307 of Clostridium sp. strain F1.

The celC gene, encoding endoglucanase C, of Clostridium thermocellum was recently sequenced while a promoter region was not identified. In this study, the nucleotide sequence of celC307 of Clostridium sp. strain F1 was identified and compared with that of the C. thermocellum gene. The open reading frame was composed of 1029 nucleotides and the deduced amino acid sequence corresponded to a protein of a molecular weight of 40,905. We identified promoter sequences (TGGACA and TATAAT) at a position about 150 nucleotides upstream of the initiation codon. Six substitutions were found in the coding region, 3 leading to amino acid replacements. Five substitutions and 1 deletion of a nucleotide were found in the region upstream of the initiation codon, 1 present at the promoter sequence. Overproduction of endoglucanase C307 (EGC307) in Escherichia coli strongly inhibited the cell growth of the host strain. Around 50% of EGC307 produced in E. coli was detected in the periplasmic fraction. The N-terminal amino acid sequence suggested that this protein was exported into the periplasm without processing of a signal peptide.