Molecular cloning and expression of a major surface protein (the 75-kDa protein) of Porphyromonas (Bacteroides) gingivalis in Escherichia coli |
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Authors: | Kan-ichi Watanabe Toshihide Takasawa Fuminobu Yoshimura Masami Ozeki Masamitsu Kawanami Hiroshi Kato |
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Affiliation: | Department of Periodontology, School of Dentistry, Hokkaido University, Sapporo, Japan. |
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Abstract: | A major immunodominant surface protein (the 75-kDa protein) of Porphyromonas (Bacteroides) gingivalis 381 has been purified and its amino-terminal amino acid sequence has been determined. Using oligonucleotide probes corresponding to the sequence, we identified a recombinant plasmid clone carrying a single 4.2-kb BamHI fragment from pUC19 libraries of P. gingivalis. The BamHI fragment transferred to the bacteriophage T7 RNA polymerase/promoter expression vector system produced a slightly larger (77-kDa) protein, a precursor form, immunoreactive to the antibody against the 75-kDa protein, suggesting that the cloned DNA fragment probably carried an entire gene for the 75-kDa protein. Genomic Southern analysis revealed a single copy of the 75-kDa protein gene per genome among all P. gingivalis strains tested, and that no homologous genes are present in other black-pigmented Bacteroides species. These observations suggest that the 75-kDa protein gene may be useful as a specific DNA probe to classify or to detect this organism. |
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Keywords: | Porphyromonas bacteroides Bacteroides gingivalis Periodontopathogen Major surface protein Gene cloning Gene expression Expression vector system |
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