RESUMO
The Pst system is a high-affinity inorganic phosphate transporter found in many bacterial species. Streptococcus mutans, the etiological agent of tooth decay, carries a single copy of the pst operon composed of six cistrons (pstS, pstC1, pstC, pstB, smu.1134 and phoU). Here, we show that deletion of pstS, encoding the phosphate-binding protein, reduces phosphate uptake and impairs cell growth, which can be restored upon enrichment of the medium with high concentrations of inorganic phosphate. The relevance of Pst for growth was also demonstrated in the wild-type strain treated with an anti-PstS antibody. Nevertheless, a reduced ability to bind to saliva-coated surfaces was observed, along with the reduction of extracellular polysaccharide production, although no difference on pH acidification was observed between mutant and wild-type strains. Taken together, the present data indicate that the S. mutans Pst system participates in phosphate uptake, cell growth and expression of virulence-associated traits.
Assuntos
Aderência Bacteriana/fisiologia , Proteínas de Transporte de Fosfato/fisiologia , Streptococcus mutans/fisiologia , Transportadores de Cassetes de Ligação de ATP/análise , Adenosina Trifosfatases/análise , Proteínas de Bactérias/análise , Película Dentária/metabolismo , Técnicas de Inativação de Genes , Inativação Gênica , Genes Bacterianos/genética , Humanos , Concentração de Íons de Hidrogênio , Proteínas de Membrana Transportadoras/análise , Mutação/genética , Óperon/genética , Proteínas de Transporte de Fosfato/genética , Proteínas de Ligação a Fosfato/análise , Fosfatos/análise , Polissacarídeos Bacterianos/metabolismo , Análise de Sequência de DNA , Streptococcus mutans/genética , Streptococcus mutans/metabolismo , Fatores de Transcrição/análise , Virulência/genéticaRESUMO
BACKGROUND: The developing periodontium is sensitive to local levels of inorganic phosphate (P(i)) and inorganic pyrophosphate (PP(i)) as demonstrated by cementum phenotypes resulting from the loss of function of protein regulators of P(i)/PP(i) homeostasis. The progressive ankylosis protein (ANK) regulates the transport of PP(i), and progressive ankylosis gene (Ank) and knock-out (KO) mice feature a rapidly forming and thick cementum. We hypothesized that, besides affecting cementum formation, decreased extracellular PP(i) levels in Ank KO mice would also impact cementum regeneration. METHODS: Periodontal fenestration defects (approximately 2 mm in length, 1 mm in width, and 0.5 mm in depth) were created on buccal aspects of mandibular molars in Ank KO and wild-type (WT) mice. Mandibles were harvested at 15 and 30 days post-surgery for histology, histomorphometry, evaluation of in vivo fluorochrome labeling, and immunohistochemistry (IHC) for proteins including bone sialoprotein (BSP), osteopontin (OPN), dentin matrix protein 1 (DMP1), and ectonucleotide pyrophosphatase/phosphodiesterase 1 (NPP1). RESULTS: A greater amount of new cementum was observed in Ank KO mice at 15 and 30 days post-surgery (P <0.05), which was confirmed by fluorochrome labeling showing a higher new cementum appositional activity in defect areas in Ank KO mice versus controls. At days 15 and 30 during healing, regenerating cementum and associated cells in Ank KO samples recapitulated expression patterns mapped during development, including limited BSP and positive OPN and DMP1 in the cementum matrix as well as elevated NPP1 in cementoblasts. CONCLUSIONS: Within the limits of the study, these findings suggest that reduced local levels of PP(i) could promote increased cementum regeneration. Therefore, the local modulation of P(i)/PP(i) may be a potential therapeutic approach for achieving improved cementum regeneration.