title: Nucleotide sequence of the Clostridium thermocellum bgIB gene encoding thermostable beta-glucosidase B: homology to fungal beta-glucosidases.
abstract: The nucleotide sequence of the bglB gene, coding for the thermostable beta-glucosidase B of Clostridium thermocellum was determined. The coding region of 2265 bp was identified by comparison with the N-terminal amino acid sequence of beta-glucosidase B purified from Escherichia coli. The derived amino acid sequence corresponding to a polypeptide of Mr 84,100 was confirmed by sequencing of the C-terminal peptide generated by cleavage with cyanogen bromide. The protein bears no resemblance to other bacterial beta-glucosidase sequences. However, extensive regions of homology were identified between the C. thermocellum enzyme and fungal beta-glucosidases. The N-terminal homologous region contains an amino acid sequence very similar to the active site of beta-glucosidase A3 from Aspergillus wentii. The striking sequence similarities between C. thermocellum beta-glucosidase B and Kluyveromyces fragilis beta-glucosidase suggest the possibility of a genetic exchange between thermophilic anaerobic bacteria and yeasts.
authors.affiliation: Institute for Microbiology, Technical University Munich, Federal Republic of Germany.
authors.forename: F
authors.initials: F
authors.lastname: Gräbnitz
authors.forename: K P
authors.initials: KP
authors.lastname: Rücknagel
authors.forename: M
authors.initials: M
authors.lastname: Seiss
authors.forename: W L
authors.initials: WL
authors.lastname: Staudenbauer
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D003013:Clostridium / Q000201:enzymology / Q000235:genetics*; D003062:Codon; D004269:DNA, Bacterial / Q000235:genetics; D005658:Fungi / Q000201:enzymology / Q000235:genetics; D005798:Genes, Bacterial; D005959:Glucosidases / Q000235:genetics*; D006358:Hot Temperature; D007716:Kluyveromyces / Q000201:enzymology / Q000235:genetics*; D008969:Molecular Sequence Data; D010957:Plasmids; D015183:Restriction Mapping; D004718:Saccharomycetales / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid; D001617:beta-Glucosidase / Q000235:genetics*
chemical_list: D003062:Codon; D004269:DNA, Bacterial; D005959:Glucosidases; D001617:beta-Glucosidase