Structure of a β-Glucosidase Gene from Ruminococcus albus and Properties of the Translated Product

概要

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A gene encoding β-glucosidase from Ruminococcus albus F-40,an anaerobic cellulolytic bacterium dominant in rumen, was cloned into Escherichia coli and sequenced. The stractural gene of the β-glucosidase consisted of 2841 bp encoding 947 amino acid residues without a characteristic signal peptide. A typical promoter sequence was located upstream of the initiation ATG codon. Palindromic sequences were found both upstream and downstream of the structural gene. Codon usege of the gene was similar to that of CMCase of R. albus, and the bias of the G+C content in the positions of the codons was negligible. The deduced amino acid sequence of R. albus β-glucosidase showed high homology with β-glucosidases from several microorganisms. There were two homologous regioun; A and B. A sequence of the supposed active region containing aspartic acid residue for Aspergillus wentii β-glucosidase A3 was conserved in region B of the R. albus β-glucosidase sequence. The gene product, β-glucosidase, was released from E. coli transformant cells into the culture supernatant, even though the gene did not encode a signal peptide. From the culture supernatant, the enzyme was purified as a homogeneous protein, of which the N-terminal amino acid sequence was identical to that of the enzyme from R. albus cells and that deduced from DNA sequence. These enzymes were also identical immunologically.
社団法人日本生物工学会の論文
1992-02-25