Characterization of an outer membrane protein gene, pgmA, and its gene product from Porphyromonas gingivalis

A gene upstream from fimA, the gene encoding fimbrilin, on the chromosome o f Porphyromonas gingivalis was sequenced and shown to be the gene encoding an outer membrane protein in this organism based on homology and biochemica l analyses, Therefore, the gene (formerly ORF5) was designated pgmA, the P. gingivalis outer membrane protein A gene. The gene product, PgmA, was sens itive to protease, and was detected as a 60-kDa protein from wild-type stra ins with trichloroacetic acid treatment, which was carried out to destroy i ntrinsic proteases, and from protease-deficient mutants without this treatm ent prior to electrophoresis, PgmA was indeed present in the membrane fract ion. Its nature was determined to be that of outer membrane proteins in gra m-negative bacteria based on attempts at differential extraction of inner m embrane proteins with detergents, No evidence has been found thus far from functional analyses that this protein is related to fimbrial morphogenesis and functions or to serum resistance of this organism.