Sialidase and Sialoglycoproteases Can Modulate Virulence in Porphyromonas gingivalis

Abstract

The Porphyromonas gingivalis recombinant VimA can interact with the gingipains and several other proteins, including a sialidase. Sialylation can be involved in protein maturation; however, its role in virulence regulation in P. gingivalis is unknown. The three sialidase-related proteins in P. gingivalis showed the characteristic sialidase Asp signature motif (SXDXGXTW) and other unique domains. To evaluate the roles of the associated genes, randomly chosen P. gingivalis isogenic mutants created by allelic exchange and designated FLL401 (PG0778::ermF), FLL402 (PG1724::ermF), and FLL403 (PG0352::ermF-ermAM) were characterized. Similar to the wild-type strain, FLL402 and FLL403 displayed a black-pigmented phenotype in contrast to FLL401, which was not black pigmented. Sialidase activity in P. gingivalis FLL401 was reduced by approximately 70% in comparison to those in FLL402 and FLL403, which were reduced by approximately 42% and 5%, respectively. Although there were no changes in the expression of the gingipain genes, their activities were reduced by 60 to 90% in all the isogenic mutants compared to that for the wild type. Immunoreactive bands representing the catalytic domains for RgpA, RgpB, and Kgp were present in FLL402 and FLL403 but were missing in FLL401. While adhesion was decreased, the capacity for invasion of epithelial cells by the isogenic mutants was increased by 11 to 16% over that of the wild-type strain. Isogenic mutants defective in PG0778 and PG0352 were more sensitive to hydrogen peroxide than the wild type. Taken together, these results suggest that the P. gingivalis sialidase activity may be involved in regulating gingipain activity and other virulence factors and may be important in the pathogenesis of this organism.

Involvement of PG2212 Zinc Finger Protein in the Regulation of Oxidative Stress Resistance in Porphyromonas gingivalis W83

“…Posttranslational modification linked to glycosylation has been shown to be important to the maturation pathway of the gingipains (50). We have also previously shown that sialidase activity may be involved in gingipain activity and other virulence factors in P. gingivalis (51). In our study, the sialidase-encoding gene (PG_0352) was downregulated in P. gingivalis FLL366 (⌬PG_2212), which would be consistent with its role in gingipain biogenesis.…”

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

“…The VimA protein can interact with the sialidase protein from P. gingivalis (2,64). Furthermore, sialidase may be involved in the posttranscriptional regulation of the gingipains (2).…”

“…Non-gingipain protease estimation was carried out using a protease assay kit (Molecular Probes) as previously described (2). The presence of Arg-X-and Lys-X-specific gingipain activities was determined as reported elsewhere (34).…”

“…The H 2 O 2 , then, in the presence of horseradish peroxidase (HRP), reacts with Amplex Red reagent to generate the redfluorescent oxidation product resorufin. The assay was read at a wavelength of 492 nm using a BioTek FLx800 microplate reader (2).…”

“…Because the specific functional roles of the vim genes are not yet fully defined, we cannot rule out the possibility that their modulation of other proteins could have similar mechanistic properties. Protein-protein interaction studies using the purified recombinant VimA (rVimA) showed that this protein can interact with the gingipains, HtrA, RegT, sialidase, and other proteins in P. gingivalis (2,47,61,64). Also, in addition to its role in glycosylation, the VimA protein can affect capsular synthesis, fimbrial phenotypic expression, and anchorage of several cell surface proteins (44).…”