Role of vimA in cell surface biogenesis in Porphyromonas gingivalis

Abstract

The Porphyromonas gingivalis vimA gene has been previously shown to play a significant role in the biogenesis of gingipains. Further, in P. gingivalis FLL92, a vimA-defective mutant, there was increased auto-aggregation, suggesting alteration in membrane surface proteins. In order to determine the role of the VimA protein in cell surface biogenesis, the surface morphology of P. gingivalis FLL92 was further characterized. Transmission electron microscopy demonstrated abundant fimbrial appendages and a less well defined and irregular capsule in FLL92 compared with the wild-type. In addition, atomic force microscopy showed that the wild-type had a smoother surface compared with FLL92. Western blot analysis using anti-FimA antibodies showed a 41 kDa immunoreactive protein band in P. gingivalis FLL92 which was missing in the wild-type P. gingivalis W83 strain. There was increased sensitivity to globomycin and vancomycin in FLL92 compared with the wild-type. Outer membrane fractions from FLL92 had a modified lectin-binding profile. Furthermore, in contrast with the wild-type strain, nine proteins were missing from the outer membrane fraction of FLL92, while 20 proteins present in that fraction from FLL92 were missing in the wild-type strain. Taken together, these results suggest that the VimA protein affects capsular synthesis and fimbrial phenotypic expression, and plays a role in the glycosylation and anchorage of several surface proteins.

Deletion of a 77-Base-Pair Inverted Repeat Element Alters the Synthesis of Surface Polysaccharides in Porphyromonas gingivalis

“…Our data do not distinguish, however, whether the low activity in the medium was due to lack of secretion of the gingipains or whether the proteins are secreted in an inactive form. In addition, a W83 strain with a mutation in VimA has been reported to express a fimbrial protein with reactivity to anti-FimA antibody that is not present in wild-type P. gingivalis W83 (36). We were unable to detect an anti-FimA reactive band in either the parent strain or the ⌬77bpIR mutant (data not shown), indicating that the 77bpIR region does not modulate expression of this protein.…”

VimA-Dependent Modulation of Acetyl Coenzyme A Levels and Lipid A Biosynthesis Can Alter Virulence in Porphyromonas gingivalis

“…The activation of these gingipains is associated with several genes, including vimA, vimE, and vimF, that modulate the posttranslational glycosylation of those proteins (44,(62)(63)(64). These genes are part of the 6. locus which has previously been shown to be important to the pathogenic potential of P. gingivalis (1,26,44,(62)(63)(64).We have demonstrated that the bcp and recA genes play the expected role in oxidative stress resistance and DNA repair, respectively (26). The association of these genes with the vim genes on the same transcriptional unit could be considered an important strategy for P. gingivalis to coordinate its oxidative stress and proteolytic activities.…”

“…The major proteases, called gingipains, consist of arginine-specific (Arg-gingipain [Rgp]) and lysine-specific (Lysgingipain [Kgp]) proteases that are both extracellular and cell membrane associated (32). The activation of these gingipains is associated with several genes, including vimA, vimE, and vimF, that modulate the posttranslational glycosylation of those proteins (44,(62)(63)(64). These genes are part of the 6. locus which has previously been shown to be important to the pathogenic potential of P. gingivalis (1,26,44,(62)(63)(64).…”

Controlling Porphyromonas gingivalis requires Vim

“…In this issue, Osbourne et al (2010) show that the VimA protein can control capsular biogenesis and fimbrial synthesis. A vimA mutant strain displayed an irregular polysaccharide capsule and more fimbriae compared with the parental strain.…”

“…Further study of VimA will undoubtedly reveal more important circuitry. It is also worthy of note that Osbourne et al (2010) showed that the VimA mutant is more sensitive to globomycin and vancomycin, making VimA function a potential target for…”