SEQUENCE AND PRODUCT ANALYSES OF THE 4 GENES DOWNSTREAM FROM THE FIMBRILIN GENE (FIMA) OF THE ORAL ANAEROBE PORPHYROMONAS-GINGIVALIS

The downstream DNA region of the fimbrilin gene (fimA), which encodes the major subunit protein of Porphyromonas gingivalis fimbriae, was fu lly sequenced. Gene products, expressed from this region in Escherichi a coli, were purified by sodium dodecyl sulfate-polyacrylamide gel ele ctrophoresis, and their partial amino acid sequences were determined t o verify open reading frames (ORFs) found in the region by DNA sequenc ing. Four ORFs, designated ORF1, ORF2, ORF3 and ORF4, were found in th e 5.8-kb PstI fragment downstream from fimA, which was previously clon ed and partially characterized by Yoshimura, Takahashi, Hibi, Takasawa , Kato, and Dickinson (Infect. Immun. 61: 5181-5189, 1993). The direct ion of transcription of all the ORFs was the same as that of fimA. The 50 and 80 kDa encoded proteins, ORF2 and ORF3, respectively, have bee n reported to be minor components associated with fimbriae. The 15 and 19 kDa proteins, ORF1 and ORF4, respectively, have been expressed in E. coli but not identified in P. gingivalis. However, all the gene pro ducts of the ORFs, expressed in E. coli, appeared to contain intact si gnal peptides based on their N-terminal amino acid sequences.