Nucleotide sequence of the Clostridium thermocellum bgIB gene encoding thermostable beta-glucosidase B: homology to fungal beta-glucosidases |
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Authors: | Folke Gräbnitz Karl P Rücknagel Monika Seiß and Walter L Staudenhauer |
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Institution: | (1) Institute for Microbiology, Technical University Munich, Arcisstrasse 21, D-8000 München 2, Federal Republic of Germany;(2) Abteilung Braunitzer, Max Planck Institute for Biochemistry, D-8033 Martinsried, Federal Republic of Germany |
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Abstract: | Summary The nucleotide sequence of the bglB gene, coding for the thermostable -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 -glucosidase B purified from Escherichia coli. The derived amino acid sequence corresponding to a polypeptide of Mr 84100 was confirmed by sequencing of the C-terminal peptide generated by cleavage with cyanogen bromide. The protein bears no resemblance to other bacterial -glucosidase sequences. However, extensive regions of homology were identified between the C. thermocellum enzyme and fungal -glucosidases. The N-terminal homologous region contains an amino acid sequence very similar to the active site of -glucosidase A3 from Aspergillus wentii. The striking sequence similarities between C. thermocellum -glucosidase B and Kluyveromyces fragilis -glucosidase suggest the possibility of a genetic exchange between thermophilic anaerobic bacteria and yeasts. |
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Keywords: | -Glucosidase" target="_blank">gif" alt="beta" align="MIDDLE" BORDER="0">-Glucosidase DNA sequence Kluyveromyces fragilis Active site Genetic exchange |
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