Project name: Porphyromonas gingivalis

Description: Bistable populations of bacteria give rise to two or more subtypes that exhibit different phenotypes. We have explored whether the periodontal pathogen, Porphyromonas gingivalis, exhibits bistable invasive phenotypes. Using a modified cell invasion assay, we show for the first time that there are two distinct sub-types within a population of P.ginigivalis strains NCTC 11834 and W50 that display differences in their ability to invade oral epithelial cells. The highly-invasive sub-types invade cells at 10-30 fold higher levels than the poorly-invasive subtype and remain highly invasive for approximately 12-16 generations. Analysis of the gingipain activity of these sub-types revealed that the highly invasive type had reduced cell-associated arginine specific protease activity. The role of arg-gingipain activity in invasion was verified by enhancement of invasion by rgpAB mutations and by inclusion of an arg-gingipain inhibitor in invasion assays using wild-type bacteria. In addition a population of DeltargpAB bacteria did not contain a hyperinvasive sub-type. Screening of the protease activity of wild-type populations of both strains identified high and low protease sub-types which also showed the corresponding reduction or enhancement of invasive capabilities. Microarray analysis of these bistable populations revealed a putative signature set of genes that include oxidative stress resistance and iron transport genes that might be key to invasion of or survival within epithelial cells.Overall design: Porphyromonas gingivalis comparison of Invasive V Non-invasive sub-types of NCTC11834 and W50 (samples 1-12 AND High V low protease subtypes (samples 13-24)Samples 1-3 were compared top 4-6 and 7-9 V 10-12 for invasive experiments and similarly for protease strain experiments

Data type: Transcriptome or Gene expression

Sample scope: Multiisolate

Relevance: Medical

Release date: 2010-08-31

Last updated: 2010-07-20