The RpoH-Mediated Stress Response in
            <i>Neisseria gonorrhoeae</i>
            Is Regulated at the Level of Activity

Laskos, Lina; Ryan, Catherine; Fyfe, Janet; Davies, John K.

doi:10.1128/jb.186.24.8443-8452.2004

Cited by 22 publications

(41 citation statements)

References 59 publications

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“…Where appropriate, media were supplemented with 7 g/ml erythromycin, 12.5 g/ml tetracycline, or 40 g/ml kanamycin. Transformation and conjugation experiments with N. gonorrhoeae were performed as described previously (12) with the exception that conjugation experiments involved mixing 5 ϫ 10 8 donor cells and 1.5 ϫ 10 9 recipient cells. Construction of an ecf mutant of N. gonorrhoeae.…”

Section: Methodsmentioning

confidence: 99%

Ecf, an Alternative Sigma Factor from Neisseria gonorrhoeae , Controls Expression of msrAB , Which Encodes Methionine Sulfoxide Reductase

et al. 2006

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A DNA microarray was used to identify genes transcribed in Neisseria gonorrhoeae using Ecf, an alternative sigma factor. No differences between the transcriptional profiles of strain FA1090 and a mutant where ecf had been inactivated could be detected when both were grown in vitro. We therefore constructed a gonococcal strain in which Ecf can be overexpressed. Some differentially expressed genes are clustered with ecf on the genome and appear to form a single transcriptional unit. Expression of the gene encoding MsrAB, which possesses methionine sulfoxide reductase activity, was also dependent on Ecf, suggesting that the regulon responds to oxidative damage. Western blotting confirmed that the increased level of MsrAB protein is dependent on the presence of Ecf.Bacterial sigma factors are essential components of the RNA polymerase holoenzyme and determine promoter selectivity and specificity. Bacteria usually contain at least one essential sigma factor, sigma-70, which is necessary for cell viability, as well as a number of accessory sigma factors that are often involved in responses to environmental stimuli or the phase of growth. The relative amount of RNA polymerase holoenzyme containing each sigma factor determines the amplitude of the expression of a specific collection of genes.We have searched the genome sequence of Neisseria gonorrhoeae strain FA1090 (GenBank accession number AE004969) for the presence of genes encoding sigma factors. As expected, there is a gene, rpoD, encoding sigma-70 (NGO0999). Only two intact genes encoding alternative sigma factors, rpoH (NGO0288) and ecf (NGO1944), were found. Laskos et al. (11) have shown that there is also an inactive RpoN-like sigma factor, RLS, although this sequence feature (NGO1766) has not been annotated as such in the publicly available annotations of the N. gonorrhoeae strain FA1090 genome sequence (GenBank accession number AE004969; annotations at www .stdgen.lanl.gov, cmr.tigr.org/tigr-scripts/CMR/CmrHomePage .cgi, and www.ncbi.nlm.nih.gov/genomes/lproks.cgi). The ecf gene encodes a member of the extracytoplasmic function (ECF) family of sigma factors. As the name suggests, ECF sigma factors from different bacterial species appear to respond specifically to a variety of extracytoplasmic stimuli. Characteristically, their activity is controlled by anti-sigma factors, and they control relatively small regulons (1). In most examples of this system investigated to date, the ECF sigma factors regulate not only their own expression but also that of the genes encoding the cognate anti-sigma factor, which are located in the same operon.We have used DNA microarrays to assess the role of the sigma factor Ecf in gonococci and show that it controls a small regulon which contains the msrAB gene, which encodes an unusual methionine sulfoxide reductase. MATERIALS AND METHODSBacterial strains, plasmids, and growth conditions. The bacterial strains and plasmids used in this study are listed in Table 1. Escherichia coli strain DH5␣ [F Ϫ endA1 thi-1 hsdR17 supE44 relA1 ⌬l...

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Section: Methodsmentioning

confidence: 99%

Ecf, an Alternative Sigma Factor from Neisseria gonorrhoeae , Controls Expression of msrAB , Which Encodes Methionine Sulfoxide Reductase

et al. 2006

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“…These results suggest that rpoH-dependent promoters are upregulated in the Fur mutant. In support of this, we also included the S1 mapping experiment of the groESEL promoter that we expect to be coregulated since it was previously reported in gonococcus as one of the rpoH-dependent genes (26,37). Indeed, in N. meningitidis the groESEL genes are transcribed from a 32 promoter, which is also upregulated in the fur mutant ( Fig.…”

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confidence: 88%

Effect ofNeisseria meningitidisFur Mutations on Global Control of Gene Transcription

et al. 2006

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The ferric uptake regulator Fur is a well-known iron-responsive repressor of gene transcription, which is used by many bacteria to respond to the low-iron environment that pathogens encounter during infection. In this study we used comparative transcriptome analysis to define the role of the Fur protein in the global control of gene transcription and iron regulation in Neisseria meningitidis. By using the Fur-null mutant and its complemented derivative, we identified 83 genes whose transcription is controlled by Fur. We report that Fur may control differential expression of these genes by binding directly to their promoters or through indirect mechanisms. In addition, mutation of the fur gene resulted in the induction of the heat shock response, and transcription of these genes does not respond to iron limitation. Furthermore, analysis of the iron starvation stimulon in the Fur-null mutant provided evidences of iron-responsive regulation that is independent of Fur. We began to dissect the regulatory networks of Fur and the heat shock (stress) response in N. meningitidis, and the observed interlink between the two circuits is discussed.

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“…This translational fusion consisted of 365 bp of DNA sequence upstream of rpoH, which included the promoter region (14), the first two codons of rpoH (Fig. 2), and a promoterless lacZ gene.…”

Section: Expression Of Rpoh and Certain Rpoh-regulated Genes Is Reprementioning

confidence: 99%

“…2). This region contains an extended 172-bp RNA leader sequence, which was previously observed to be involved in rpoH repression during growth under normal conditions (14). To determine if the leader sequence was involved in MtrR repression of rpoH, an internal deletion was engineered within the rpoH-lacZ construct and transformed into strains FA19 and JF1 (FA19 ⌬mtrR) to create strains JF14 (FA19 rpoH-lacZ) and JF15 (FA19 ⌬mtrR rpoHlacZ) (Table 1), respectively, and expression was measured.…”

Section: Expression Of Rpoh and Certain Rpoh-regulated Genes Is Reprementioning

confidence: 99%

MtrR Modulates rpoH Expression and Levels of Antimicrobial Resistance in Neisseria gonorrhoeae

et al. 2009

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The MtrR transcriptional-regulatory protein is known to repress transcription of the mtrCDE operon, which encodes a multidrug efflux pump possessed by Neisseria gonorrhoeae that is important in the ability of gonococci to resist certain hydrophobic antibiotics, detergents, dyes, and host-derived antimicrobials. In order to determine whether MtrR can exert regulatory action on other gonococcal genes, we performed a whole-genome microarray analysis using total RNA extracted from actively growing broth cultures of isogenic MtrR-positive and MtrR-negative gonococci. We determined that, at a minimum, 69 genes are directly or indirectly subject to MtrR control, with 47 being MtrR repressed and 22 being MtrR activated. rpoH, which encodes the general stress response sigma factor RpoH (sigma 32), was found by DNA-binding studies to be directly repressed by MtrR, as it was found to bind to a DNA sequence upstream of rpoH that included sites within the rpoH promoter. MtrR also repressed the expression of certain RpoH-regulated genes, but this regulation was likely indirect and a reflection of MtrR control of rpoH expression. Inducible expression of MtrR was found to repress rpoH expression and to increase gonococcal susceptibility to hydrogen peroxide (H 2 O 2 ) and an antibiotic (erythromycin) recognized by the MtrC-MtrD-MtrE efflux pump system. We propose that, apart from its ability to control the expression of the mtrCDE-encoded efflux pump operon and, as a consequence, levels of gonococcal resistance to host antimicrobials (e.g., antimicrobial peptides) recognized by the efflux pump, the ability of MtrR to regulate the expression levels of rpoH and RpoH-regulated genes also modulates levels of gonococcal susceptibility to H 2 O 2 .

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The RpoH-Mediated Stress Response in Neisseria gonorrhoeae Is Regulated at the Level of Activity

Cited by 22 publications

References 59 publications

Ecf, an Alternative Sigma Factor from Neisseria gonorrhoeae , Controls Expression of msrAB , Which Encodes Methionine Sulfoxide Reductase

Ecf, an Alternative Sigma Factor from Neisseria gonorrhoeae , Controls Expression of msrAB , Which Encodes Methionine Sulfoxide Reductase

Effect ofNeisseria meningitidisFur Mutations on Global Control of Gene Transcription

MtrR Modulates rpoH Expression and Levels of Antimicrobial Resistance in Neisseria gonorrhoeae

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