Oxidative stress tolerance is manganese (Mn2+) regulated in Streptococcus gordonii

Jakubovics, Nicholas S.; Smith, Anthony W.; Jenkinson, Howard F.

doi:10.1099/00221287-148-10-3255

Cited by 55 publications

(66 citation statements)

References 45 publications

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“…This is consistent with a role for Mn# + in the readthrough transcription of the psaD thiol peroxidase in S. pneumoniae (Novak et al, 1998). In contrast, there is no evidence to support regulation of the S. gordonii thiol peroxidase by Mn# + since Northern blots do not reveal co-transcription of the tpx gene and the upstream permease operon (Jakubovics et al, 2000).…”

Section: Discussionmentioning

confidence: 81%

Evidence that ORF3 at the Streptococcus parasanguis fimA locus encodes a thiol-specific antioxidant

et al. 2002

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Streptococcus parasanguis is a primary colonizer of dental plaque and a major player in subacute bacterial endocarditis. In the present study, the authors report that an ORF (ORF3) located 77 bp downstream of the fimA operon on the S. parasanguis FW213 chromosome complements an Escherichia coli thiol peroxidase (tpx) mutation in glutamine synthetase (GS) protection assays and that GS is protected by the ORF3 gene product in S. parasanguis cell extracts. In addition, the putative streptococcal peroxidase (Tpx Sp ) protects S. parasanguis from stress caused by H 2 O 2 and is induced by oxygen, as revealed by Northern blot analysis. Taken collectively, these findings support a thiol-dependent antioxidant activity for Tpx in S. parasanguis.

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Section: Discussionmentioning

confidence: 81%

Evidence that ORF3 at the Streptococcus parasanguis fimA locus encodes a thiol-specific antioxidant

et al. 2002

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“…In many bacteria, the tpx mutant has decreased resistance to H 2 O 2 (8,16,30). Hence, the resistance to moderate (0.5 mM) and high (20 and 50 mM) concentrations of H 2 O 2 in the ⌬tpx mutant and in the PAO1 wild type were determined.…”

Section: Resultsmentioning

confidence: 99%

Pseudomonas aeruginosa Thiol Peroxidase Protects against Hydrogen Peroxide Toxicity and Displays Atypical Patterns of Gene Regulation

et al. 2012

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The Pseudomonas aeruginosa PAO1 thiol peroxidase homolog (Tpx) belongs to a family of enzymes implicated in the removal of toxic peroxides. We have shown the expression of tpx to be highly inducible with redox cycling/superoxide generators and diamide and weakly inducible with organic hydroperoxides and hydrogen peroxide (H 2 O 2 ). The PAO1 tpx pattern is unlike the patterns for other peroxide-scavenging genes in P. aeruginosa. Analysis of the tpx promoter reveals the presence of a putative IscR binding site located near the promoter. The tpx expression profiles in PAO1 and the iscR mutant, together with results from gel mobility shift assays showing that purified IscR specifically binds the tpx promoter, support the role of IscR as a transcriptional repressor of tpx that also regulates the oxidant-inducible expression of the gene. Recombinant Tpx has been purified and biochemically characterized. The enzyme catalyzes thioredoxin-dependent peroxidation and can utilize organic hydroperoxides and H 2 O 2 as substrates. The ⌬tpx mutant demonstrates differential sensitivity to H 2 O 2 only at moderate concentrations (0.5 mM) and not at high (20 mM) concentrations, suggesting a novel protective role of tpx against H 2 O 2 in P. aeruginosa. Altogether, P. aeruginosa tpx is a novel member of the IscR regulon and plays a primary role in protecting the bacteria from submillimolar concentrations of H 2 O 2 .

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“…In streptococci, Nox, SOD, and Dpr are thought to play major roles in oxidative stress tolerance (16,23,26,35) and are highly inducible by oxidative stresses. Elevated expression of the respective genes in TW14 therefore suggests that BrpA deficiency may signal oxidative stress.…”

Section: Resultsmentioning

confidence: 99%

Influence of BrpA on Critical Virulence Attributes ofStreptococcus mutans

Wen

Baker

Burne³

2006

J Bacteriol

114

183

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Streptococcus mutans, the primary etiological agent of human dental caries, has developed multiple mechanisms to colonize and form biofilms on the tooth surface. The brpA gene codes for a predicted surfaceassociated protein with apparent roles in biofilm formation, autolysis, and cell division. In this study, we used two models to further characterize the biofilm-forming characteristics of a BrpA-deficient mutant, strain TW14. Compared to those of the parent strain, UA159, TW14 formed long chains and sparse microcolonies on hydroxylapatite disks but failed to accumulate and form three-dimensional biofilms when grown on glucose as the carbohydrate source. The biofilm formation defect was also readily apparent by confocal laser scanning microscopy when flow cells were used to grow biofilms. When subjected to acid killing at pH 2.8 for 45 min, the survival rate of strain TW14 was more than 1 log lower than that of the wild-type strain. TW14 was at least 3 logs more susceptible to killing by 0.2% hydrogen peroxide than was UA159. The expression of more than 200 genes was found by microarray analysis to be altered in cells lacking BrpA (P < 0.01). These results suggest that the loss of BrpA can dramatically influence the transcriptome and significantly affects the regulation of acid and oxidative stress tolerance and biofilm formation in S. mutans, which are key virulence attributes of the organism.Streptococcus mutans, the primary etiological agent of human dental caries, exists almost exclusively in biofilms on tooth surfaces. The pathogenic potential of S. mutans is attributable to potent biofilm-forming abilities, a high capacity to produce acids, a high degree of acid tolerance, and the possession of high-affinity systems for the assimilation of many carbohydrate sources (9).Biofilms are surface-attached, structurally and compositionally complex bacterial communities (17,(31)(32)(33). Accumulating data suggest that bacterial cells in biofilms interact with and coordinate the expression of a wide range of genes in response to evolving environmental conditions, including pH, oxygen, carbon source and nutrient availability, cell density, and the presence of a solid surface. A series of highly coordinated physiological and biochemical functions is required for the bacteria to form mature biofilms in response to environmental cues (17,(31)(32)(33). The development of highly structured biofilms, however, gives the adherent populations the flexibility to cope with fluctuating environments and the selective advantages that surface association offers (17).Recent studies have revealed that several genetic regulatory networks in S. mutans are required for bacterial adherence, biofilm accumulation, and growth under the conditions encountered during biofilm formation. The cell-density-dependent Com system, which is known to regulate genetic competence in S. mutans and other naturally competent streptococci, plays a significant role in biofilm formation and acid tolerance (20, 21). The LuxS enzyme, which is responsible for th...

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Oxidative stress tolerance is manganese (Mn2+) regulated in Streptococcus gordonii

Cited by 55 publications

References 45 publications

Evidence that ORF3 at the Streptococcus parasanguis fimA locus encodes a thiol-specific antioxidant

Evidence that ORF3 at the Streptococcus parasanguis fimA locus encodes a thiol-specific antioxidant

Pseudomonas aeruginosa Thiol Peroxidase Protects against Hydrogen Peroxide Toxicity and Displays Atypical Patterns of Gene Regulation

Influence of BrpA on Critical Virulence Attributes ofStreptococcus mutans

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