Oral microbial heat-shock proteins and their potential contributions to infections.

The oral cavity is a complex ecosystem in which several hundred microbial species normally cohabit harmoniously. However, under certain special conditions, the growth of some micro-organisms with a pathogenic potential is promoted, leading to infections such as dental caries, periodontal disease, and stomatitis. The physiology and pathogenic properties of micro-organisms are influenced by modifications in environmental conditions that lead to the synthesis of specific proteins known as the heat-shock proteins (HSPs).

Modulation of Porphyromonas gingivalis proteinase activity by suboptimal doses of antimicrobial agents.

Background: Antimicrobial agents are sometimes used as adjuncts for the treatment of aggressive and refractory forms of periodontitis. In this study, we used a culture plate assay to investigate the effect of suboptimal doses of antimicrobial agents on proteinase activity of Porphyromonas gingivalis.

Methods: A culture plate assay using gelatin as the substrate, which allows a semiquantitative determination of proteinase activity, was developed.

Effect of hydroxamic acid-based matrix metalloproteinase inhibitors on human gingival cells and Porphyromonas gingivalis.

Background: Matrix metalloproteinases (MMPs) are considered to play key roles in tissue destruction during periodontitis. In this study, we evaluated the cytotoxicity of hydroxamic acid-based MMP inhibitors (ONO-4817, ONO-MI1-514, and ONO-MI1-570), and their inhibitory effects on MMP-2 and -9 activities and growth of Porphyromonas gingivalis.

Methods: Human gingival fibroblasts (HGF) and human gingival epithelial cells (HGE) were incubated with test inhibitors prior to investigating cell viability, cell proliferation, and mRNA expression for MMP-2 and -9.

Effect of inactivation of the Arg- and/or Lys-gingipain gene on selected virulence and physiological properties of Porphyromonas gingivalis.

Proteolytic enzymes produced by Porphyromonas gingivalis are thought to play critical roles in the pathogenesis of periodontitis. The aim of this study was to investigate the effect of gingipain cysteine proteinase gene inactivation on selected pathological and physiological functions of P. gingivalis.

Monitoring the uptake of protein-derived peptides by Porphyromonas gingivalis with fluorophore-labeled substrates.

The aim of this study was to develop a simple method to quantify peptide uptake by the periodontopathogenic bacterium Porphyromonas gingivalis. After incubation of bacterial cells with self-quenched fluorescent bovine serum albumin (DQ Green BSA), the fluorescence measured in the supernatant of the assay mixture indicated the degree of protein degradation, whereas the fluorescence associated with the lysate of washed cells indicated the amount of BSA-derived fragments incorporated by the bacteria. The optimal conditions for uptake of fluorophore-labeled albumin fragments were found to be mid-log grown cells, 150 m M NaCl in phosphate buffer, pH 7, 37 degrees C, and anaerobiosis.

Stress response in Actinobacillus actinomycetemcomitans: induction of general and specific stress proteins.

Stress proteins are highly conserved proteins that are essential for cell survival. In this study, the induction of general and specific stress proteins in Actinobacillus actinomycetemcomitans cells subjected to different stress conditions was evaluated by two-dimensional SDS-PAGE analysis. Twenty-eight (up- or down)regulated proteins, including DnaK and GroEL proteins, were identified as general stress proteins.