Cloning and sequencing of an endoglucanase (end1) gene from Butyrivibrio fibrisolvens H17c

The nucleotide sequence of a 2.8 kb DNA segment containing an endoglucanase gene (end1) from Butyrivibrio fibrisolvens H17c was determined. The B. fibrisolvens H17c gene was expressed from its own regulatory region in Escherichia coli and three putative consensus promoter sequences were identified upstream of a ribosome binding site and an ATG start codon. The complete amino acid sequence (547 residues) was deduced and homology with the Clostridium thermocellum celE gene product (EGE) was demonstrated. The endoglucanase contained a typical amino-terminal signal sequence and five repeated sequences (PDPTPVD) between amino acids 412-447. The endoglucanase showed relatively high endoglucanase activity against endoglucanase-specific substrates with beta 1-4 linkages but low activity against xylan and an exoglucanase-specific substrate, p-nitrophenyl-beta-D-cellobioside.