Role of the <i>Porphyromonas gingivalis</i> extracytoplasmic function sigma factor, SigH

Yanamandra, Sai S.; Sarrafee, Sara S.; Anaya-Bergman, Cecilia; Jones, Kathryn; Lewis, Janina P.

doi:10.1111/j.2041-1014.2012.00643.x

Cited by 31 publications

(34 citation statements)

References 63 publications

(154 reference statements)

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“…In both parent and mutant strains Na + depletion lead to significant upregulation of genes previously identified as responsive to oxidative stress in P. gingivalis [22], [23]. As shown in Table 2, these included formate-tetrahydrofolate ligase (PG1321), formate-nitrite transporter (PG0209), thiol peroxidase (PG1729), ferritin (PG1286) and thioredoxin (PG0034).…”

Section: Resultsmentioning

confidence: 95%

“…2 hr in medium with and without Na + (Table 2). Under Na + -depleted conditions both parent and mutant strains appeared to undergo oxidative stress as evidenced by up-regulation of genes known to be involved in the response [9], [22], [23], [25]. In most cases the relative levels of expression were greater in the rprY mutant than in the parent indicating that the regulator controls expression of genes important for growth and survival under these conditions.…”

Section: Discussionmentioning

confidence: 99%

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Role of Sodium in the RprY-Dependent Stress Response in Porphyromonas gingivalis

Krishnan

Duncan²

2013

PLoS ONE

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Porphyromonas gingivalis is a Gram-negative oral anaerobe which is strongly associated with periodontal disease. Environmental changes in the gingival sulcus trigger the growth of P. gingivalis and a concurrent shift from periodontal health to disease. Bacteria adjust their physiology in response to environmental changes and gene regulation by two-component phospho-relay systems is one mechanism by which such adjustments are effected. In P. gingivalis RprY is an orphan response regulator and previously we showed that the RprY regulon included genes associated with oxidative stress and sodium metabolism. The goals of the present study were to identify environmental signals that induce rprY and clarify the role of the regulator in the stress response. In Escherichia coli an RprY-LacZ fusion protein was induced in sodium- depleted medium and a P. gingivalis rprY mutant was unable to grow in similar medium. By several approaches we established that sodium depletion induced up-regulation of genes involved in oxidative stress. In addition, we demonstrated that RprY interacted directly with the promoters of several molecular chaperones. Further, both genetic and transcription data suggest that the regulator acts as a repressor. We conclude that RprY is one of the regulators that controls stress responses in P. gingivalis, possibly by acting as a repressor since an rprY mutant showed a superstress reponse in sodium-depleted medium which we propose inhibited growth.

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Section: Resultsmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 99%

Role of Sodium in the RprY-Dependent Stress Response in Porphyromonas gingivalis

Krishnan

Duncan²

2013

PLoS ONE

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“…The P. gingivalis W83 transcriptome was determined as described previously (61). Reads were aligned to the reference genome using the CLC Genomics Workbench (CLC Bio).…”

Section: Methodsmentioning

confidence: 99%

HcpR of Porphyromonas gingivalis Is Required for Growth under Nitrosative Stress and Survival within Host Cells

2012

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ABSTRACTAlthough the Gram-negative, anaerobic periodontopathogenPorphyromonas gingivalismust withstand nitrosative stress, which is particularly high in the oral cavity, the mechanisms allowing for protection against such stress are not known in this organism. In this study, microarray analysis ofP. gingivalistranscriptional response to nitrite and nitric oxide showed drastic upregulation of the PG0893 gene coding for hybrid cluster protein (Hcp), which is a putative hydroxylamine reductase. Although regulation ofhcphas been shown to be OxyR dependent inEscherichia coli, here we show that inP. gingivalisits expression is dependent on the Fnr-like regulator designated HcpR. Growth of the isogenic mutant V2807, containing anermF-ermAMinsertion within thehcpR(PG1053) gene, was significantly reduced in the presence of nitrite (P< 0.002) and nitric oxide-generating nitrosoglutathione (GSNO) (P< 0.001), compared to that of the wild-type W83 strain. Furthermore, the upregulation of PG0893 (hcp) was abrogated in V2807 exposed to nitrosative stress. In addition, recombinant HcpR bound DNA containing thehcppromoter sequence, and the binding was hemin dependent. Finally, V2807 was not able to survive with host cells, demonstrating that HcpR plays an important role inP. gingivalisvirulence. This work gives insight into the molecular mechanisms of protection against nitrosative stress inP. gingivalisand shows that the regulatory mechanisms differ from those inE. coli.

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“…The ECF sigma factors have been reported to be involved in virulence regulation in pathogenic bacteria including Mycobacterium tuberculosis , Staphylococcus aureus , Pseudomonas aeruginosa , and Enterococcus faecalis (Hahn et al ., ; Shaw et al ., ; Llamas et al ., ; Wood & Ohman, ; Le et al ., ). The P. gingivalis W83 genome encodes eight sigma factors, six of which belong to the ECF sigma factor subfamily [PG0162, PG0214, PG0985, PG1318, PG1660, and PG1827 (SigH)] (Nelson et al ., ; Yanamandra et al ., ). Previous studies have demonstrated a role for several of the ECF sigma factors for survival of P. gingivalis in the presence of oxygen, hydrogen peroxide, and thiol‐induced stress (Dou et al ., ; Yanamandra et al ., ).…”

Section: Introductionmentioning

confidence: 97%

“…The P. gingivalis W83 genome encodes eight sigma factors, six of which belong to the ECF sigma factor subfamily [PG0162, PG0214, PG0985, PG1318, PG1660, and PG1827 (SigH)] (Nelson et al ., ; Yanamandra et al ., ). Previous studies have demonstrated a role for several of the ECF sigma factors for survival of P. gingivalis in the presence of oxygen, hydrogen peroxide, and thiol‐induced stress (Dou et al ., ; Yanamandra et al ., ). In addition, its function as a positive regulator of hemin uptake and virulence regulation in this bacterium is documented (Yanamandra et al ., ).…”

Section: Introductionmentioning

confidence: 97%

Studies of the extracytoplasmic function sigma factor PG0162 in Porphyromonas gingivalis

Dou

Aruni

Muthiah

et al. 2015

Molecular Oral Microbiology

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SUMMARY PG0162, annotated as an extracytoplasmic function (ECF) sigma factor in Porphyromonas gingivalis, is composed of 193 amino acids. As previously reported, the PG0162-deficient mutant, P. gingivalis FLL350 showed significant reduction in gingipain activity compared to the parental strain. Because this ECF sigma factor could be involved in the virulence regulation in P. gingivalis, its genetic properties were further characterized. A 5’-RACE analysis showed that the start of transcription of the PG0162 gene occurred from a guanine (G) residue 69 nucleotides upstream of the ATG translation initiation codon. The function of PG0162 as a sigma factor was confirmed in a run-off in vitro transcription assay using the purified rPG0162 and RNAP core enzyme from E.coli with the PG0162 promoter as template. Since an appropriate PG0162 inducing environmental signal is unknown, a strain overexpressing the PG0162 gene designated P. gingivalis FLL391 was created. Compared to the wild-type strain, transcriptome analysis of P. gingivalis FLL391 showed that approximately 24% of the genome displayed altered gene expression (260 upregulated genes; 286 downregulated genes). Two other ECF sigma factors (PG0985 and PG1660) were upregulated more than 2 fold. The autoregulation of PG0162 was confirmed with the binding of the rPG0162 protein to the PG0162 promoter in electrophoretic mobility shift assay. In addition, the rPG0162 protein also showed the ability to bind to the promoter region of two genes (PG0521 and PG1167) that were most upregulated in P. gingivalis FLL391. Taken together, our data suggest that PG0162 is a sigma factor that may play an important role in the virulence regulatory network in P. gingivalis.

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Role of the Porphyromonas gingivalis extracytoplasmic function sigma factor, SigH

Cited by 31 publications

References 63 publications

Role of Sodium in the RprY-Dependent Stress Response in Porphyromonas gingivalis

Role of Sodium in the RprY-Dependent Stress Response in Porphyromonas gingivalis

HcpR of Porphyromonas gingivalis Is Required for Growth under Nitrosative Stress and Survival within Host Cells

Studies of the extracytoplasmic function sigma factor PG0162 in Porphyromonas gingivalis

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