Multiple enzymes can make hydrogen sulfide from cysteine in Treponema denticola.

Treponema denticola is a spirochete that is involved in causing periodontal diseases. This bacterium can produce HS from thiol compounds found in the gingival crevicular fluid. Determining how HS is made by oral bacteria is important since this molecule is present at high levels in periodontally-diseased pockets and the biological effects of HS can explain some of the pathologies seen in periodontitis.

Glutathione catabolism by Treponema denticola impacts its pathogenic potential.

Treponema denticola is a spirochete that is etiologic for periodontal diseases. This bacterium is one of two periodontal pathogens that have been shown to have a complete three step enzymatic pathway (GTSP) that catabolizes glutathione to HS. This pathway may contribute to the tissue pathology seen in periodontitis since diseased periodontal pockets have lower glutathione levels than healthy sites with a concomitant increase in HS concentration.

Effect of Bacterial Biofilm on the Osteogenic Differentiation of Stem Cells of Apical Papilla.

Introduction: Although clinical success in regenerative endodontics is substantially high, histological success is limited to finding bone/cementum-like tissue instead of dentin within the canal space. The aims of this study were to investigate (1) the effect of bacterial biofilm on osteogenic gene expression in stem cells of the apical papilla (SCAP) and (2) the effect of bacterial antigens on the functional differentiation of SCAP into a mineralizing phenotype.

Methods: Using an ex vivo organotypic root canal model and an American Association of Endontists-recommended regenerative endodontic procedures, we evaluated SCAP differentiation in the presence and absence of an Enterococcus faecalis biofilm.

Mlc is a transcriptional activator with a key role in integrating cyclic AMP receptor protein and integration host factor regulation of leukotoxin RNA synthesis in Aggregatibacter actinomycetemcomitans.

Aggregatibacter actinomycetemcomitans, a periodontal pathogen, synthesizes leukotoxin (LtxA), a protein that helps the bacterium evade the host immune response. Transcription of the ltxA operon is induced during anaerobic growth. The cyclic AMP (cAMP) receptor protein (CRP) indirectly increases ltxA expression, but the intermediary regulator is unknown.

The cyclic-AMP receptor protein (CRP) regulon in Aggregatibacter actinomycetemcomitans includes leukotoxin.

The cyclic-AMP receptor protein (CRP) acts as a global regulatory protein among bacteria. Here, the CRP regulon has been defined in Aggregatibacter actinomycetemcomitans using microarray analysis of A. actinomycetemcomitans strain JP2 wild type cells compared to an isogenic crp deletion mutant.

Repression of aerobic leukotoxin transcription by integration host factor in Aggregatibacter actinomycetemcomitans.

Aggregatibacter actinomycetemcomitans has been implicated as the primary etiologic agent in localized aggressive periodontitis. This bacterium produces a leukotoxin which may help the bacterium evade the host immune response. Leukotoxin transcription is induced when A.

A 52-kDa leucyl aminopeptidase from treponema denticola is a cysteinylglycinase that mediates the second step of glutathione metabolism.

The metabolism of glutathione by the periodontal pathogen Treponema denticola produces hydrogen sulfide, which may play a role in the host tissue destruction seen in periodontitis. H2S production in this organism has been proposed to occur via a three enzyme pathway, gamma-glutamyltransferase, cysteinylglycinase (CGase), and cystalysin. In this study, we describe the purification and characterization of T.

Evaluation of ultrasonically placed MTA and fracture resistance with intracanal composite resin in a model of apexification.

The purpose of this study was to evaluate whether intracoronal delivery of an apical barrier of mineral trioxide aggregate (MTA) placed ultrasonically, non-ultrasonically, or ultrasonically with the addition of an intracanal composite resin provided a better seal against bacterial leakage. A second purpose was to determine whether intracanal composite resin or gutta-percha and sealer placed against an apical barrier of MTA provided greater resistance to root fracture. In a standardized in vitro open apex model, MTA was placed as an apical barrier at a thickness of 4 mm, with and without ultrasonic vibration.

Anaerobic regulation of Actinobacillus actinomycetemcomitans leukotoxin transcription is ArcA/FnrA-independent and requires a novel promoter element.

The periodontal pathogen, Actinobacillus actinomycetemcomitans, produces a 116-kDa leukotoxin that appears to help the bacterium evade the innate host immune response. The expression of leukotoxin is induced when cells are grown anaerobically, a condition found in the subgingival crevice. This regulation most likely occurs at the transcriptional stage since the levels of leukotoxin RNA are induced by hypoxic growth.

Construction and analysis of hemin binding protein mutants in the oral pathogen Treponema denticola.

Treponema denticola, a periodontal pathogen, can use hemin as its sole iron source. The organism synthesizes two low-iron-induced outer-membrane hemin-binding proteins, HbpA and HbpB. To characterize genetically the function of these two novel proteins, standard recombinant DNA procedures and electroporation were used to construct T.

Molecular Genetics and the Analysis of Leukotoxin in A. actinomycetemcomitans.

The primary pathogen involved in certain forms of early-onset periodontitis is A. actinomycetemcomitans. Among its numerous potential virulence factors is a leukotoxin that kills certain host defense cells.