Molecular cloning and sequencing of the fimbrilin gene of Porphyromonas gingivalis strains and characterization of recombinant proteins.
The fimA gene encoding the subunit protein of fimbriae, fimbrilin, from nine strains of Porphyromonas gingivalis was cloned using polymerase chain reaction and the nucleotide sequence was determined. Analysis of the nucleotide and the deduced amino acid sequences revealed that the fimA gene of the test strains was composed of 1044 to 1083 bp, and the molecular weight of the deduced polypeptides was calculated to be 37,527 to 38,239. All the test strains shared the same or similar sequences, but simultaneously considerable differences in the sequences were found among the strains. Western blot analysis using rabbit antiserum to P. gingivalis 381 fimbriae demonstrated that the recombinant fimbrilins of 8 out of 9 strains expressed in Escherichia coli reacted with the antiserum exhibiting a 43 to 48 kDa band. Taken together, these results indicate that four genetical clusters are noted among the fimA gene of P. gingivalis strains.