Quantitative proteomics of intracellular Porphyromonas gingivalis

Abstract

Whole-cell quantitative proteomic analyses were conducted to investigate the change from an extracellular to intracellular lifestyle for Porphyromonas gingivalis, a Gram-negative intracellular pathogen associated with periodontal disease. Global protein abundance data for P. gingivalis strain ATCC 33277 internalized for 18 hours within human gingival epithelial cells and controls exposed to gingival cell culture medium were obtained at sufficient coverage to provide strong evidence that these changes are profound. A total of 385 proteins were over-expressed in internalized P. gingivalis relative to controls; 240 proteins were shown to be under-expressed. This represented in total about 28% of the protein encoding ORFs annotated for this organism, and slightly less than half of the proteins that were observed experimentally. Production of several proteases, including the classical virulence factors RgpA, RgpB, and Kgp, was decreased. A separate validation study was carried out in which a 16-fold dilution of the P. gingivalis proteome was compared to the undiluted sample in order to assess the quantitative false negative rate (all ratios truly alternative). Truly null (no change) abundance ratios from technical replicates were used to assess the rate of quantitative false positives over the entire proteome. A global comparison between the direction of abundance change observed and previously published bioinformatic gene pair predictions for P. gingivalis will assist with future studies of P. gingivalis gene regulation and operon prediction.

Porphyromonas gingivalis Ferrous Iron Transporter FeoB1 Influences Sensitivity to Oxidative Stress

“…Furthermore, P. gingivalis has been demonstrated to invade and survive in host cells, and the presence of FeoB1 would be expected to have deleterious effects on survival of the internalized bacterium. This is consistent with previous observations that demonstrated reduced levels of iron uptake proteins in epithelial cell-internalized bacteria compared with those in extracellular P. gingivalis (20).…”

“…Importantly, iron did not affect feoB1 expression. This contradicts the results of a previous study (20) that attributed the observed downregulation of metal uptake mechanisms in P. gingivalis exposed to host cells to increased iron content of the host cells. Our results demonstrate that the regulation of transcription of P. gingivalis feoB1 is novel compared with the mechanisms of regulation of previously reported feoB1 homologs (2).…”

Proteome Analysis of Coinfection of Epithelial Cells with Filifactor alocis and Porphyromonas gingivalis Shows Modulation of Pathogen and Host Regulatory Pathways

“…Successful pathogens have developed novel strategies, including bacterially induced epigenetic deregulation that may affect host cell function to facilitate their survival and persistence. Proteomics analyses have significantly contributed toward a deeper understanding of the molecular mechanisms utilized by several oral pathogens such as Streptococcus mutans (30), Streptococcus oralis (31), Fusobacterium nucleatum (32), and P. gingivalis (33)(34)(35) during their interaction with the host. In a previous host-pathogen interaction study performed with epithelial cells, we showed proteome variation in F. alocis with upregulation of many important bacterial proteins (36) that could potentially trigger direct or indirect epigenetic modifications in the host.…”

Role of Porphyromonas gingivalis Phosphoserine Phosphatase Enzyme SerB in Inflammation, Immune Response, and Induction of Alveolar Bone Resorption in Rats

“…The adverse effects on the JE may result from the inability of the SerB mutant to penetrate the tissue and thus remain extracellular. Extracellular P. gingivalis organisms are more intensely proteolytic than their intracellular counterparts (63), and protease activity may contribute to apical migration of the JE (20,30). Enhanced PMN infiltration in response to the mutant is likely the direct result of the loss of the SerB enzyme.…”