Porphyromonas gingivalis Genes Involved in Community Development with Streptococcus gordonii

Abstract

Porphyromonas gingivalis, one of the causative agents of adult periodontitis, develops biofilm microcolonies on substrata of Streptococcus gordonii but not on Streptococcus mutans. P. gingivalis genome microarrays were used to identify genes differentially regulated during accretion of P. gingivalis in heterotypic biofilms with S. gordonii. Thirty-three genes showed up-or downregulation by array analysis, and differential expression was confirmed by quantitative reverse transcription-PCR. The functions of the regulated genes were predominantly related to metabolism and energy production. In addition, many of the genes have no current known function. The roles of two upregulated genes, ftsH (PG0047) encoding an ATP-dependent zinc metallopeptidase and ptpA (PG1641) encoding a putative tyrosine phosphatase, were investigated further by mutational analysis. Strains with mutations in these genes developed more abundant biofilms with S. gordonii than the parental strain developed. ftsH and ptpA may thus participate in a regulatory network that constrains P. gingivalis accumulation in heterotypic biofilms. This study provided a global analysis of P. gingivalis transcriptional responses in an oral microbial community and also provided insight into the regulation of heterotypic biofilm development.Periodontal diseases are a group of infections characterized by destruction of the supporting structures of the teeth. Porphyromonas gingivalis is a gram-negative anaerobe that is an important pathogen in severe manifestations of these diseases (15,41). With regard to the disease process, the primary ecological niche of P. gingivalis is in the subgingival area, where toxic products, such as proteases, can readily access the periodontal tissues. However, initial colonization of the oral cavity by P. gingivalis involves attachment to sites remote from the subgingival area, including the supragingival tooth surface (28,39,43,47,57,58). Indeed, introduction of P. gingivalis into the mouths of human volunteers results in localization almost exclusively on supragingival surfaces (39). The bacterial inhabitants of the supragingival tooth surface comprise a complex multispecies biofilm (42), and numerous in vitro studies have demonstrated the ability of P. gingivalis to attach to common constituents of the supragingival biofilm, including Actinomyces species and oral streptococci (12, 35). The molecular basis of P. gingivalis adhesion to Streptococcus gordonii has been investigated in some detail and has been shown to be multivalent (3,4,23,24,45). The P. gingivalis long fimbriae (FimA) bind to glyceraldehyde-3-phosphate dehydrogenase present on the streptococcal surface (27). In addition, the P. gingivalis short fimbriae (Mfa) engage the streptococcal SspA/B (antigen I/II) adhesins (33) through an approximately 80-amino-acid binding epitope of SspA/B termed BAR (11). Coadhesion mediated through these effectors is required for P. gingivalis to accumulate in a heterotypic biofilm with S. gordonii (23).In contrast to the synergistic rela...

Two-component signal transduction systems in oral bacteria

“…The third signal transduction system could be defined as a variant of the TCS in the sense that the activation of the RR by the sensor protein involves multiple steps of transference of the phosphate group to intermediary proteins [17]. Additional phosphate signalling activities with similarities to eukaryotic pathways have been detected in prokaryotes including P. gingivalis [18,19]. …”

The Role of Oral Pathobionts in Dysbiosis during Periodontitis Development

“…Because of the similarity among proteobacteria, it is possible that oral proteobacteria might also control neighboring bacteria through T5SS-and T6SS-dependent mechanisms. Co-incubation of Pg with S. gordonii induces expression of Ltp1, a native regulator of Mfa fimbriae and LuxS in Pg, perhaps for optimization of bacterial ratio during biofilm formation (Simionato et al, 2006). Therefore, inhibitory interactions among bacteria may not only regulate competition among neighboring bacteria, but also stabilize the bacterial community or change the composition of the microbiota during periodontitis development.…”

“…important for contact-dependent inhibition of neighboring bacteria in airborne and enteric proteobacteria (Simionato et al, 2006). Because of the similarity among proteobacteria, it is possible that oral proteobacteria might also control neighboring bacteria through T5SS-and T6SS-dependent mechanisms.…”

The role of kinases and phosphatases in the pathobiology of porphyromonas gingivalis.

“…Transcription of ltp1 is increased following contact with S. gordonii [125], and Ltp1 is a component of a signaling pathway that converges on the LuxR family transcriptional regulator CdhR [126]. The expression of the P. gingivalis…”

“…In community-associated P. gingivalis, there is upregulation of ltp1, a gene encoding a cytoplasmic eukaryotic-type Low Molecular Weight Tyrosine Phosphatase [125]. Ltp1 is responsible for restricting community development of P. gingivalis with S.…”