SuhB Is a Regulator of Multiple Virulence Genes and Essential for Pathogenesis of Pseudomonas aeruginosa

Li, Kewei; Xu, Chang; Jin, Yongxin; Sun, Ziyu; Liu, Chang; Shi, Jing; Chen, Gukui; Chen, Ronghao; Jin, Shouguang; Wu, Weihui

doi:10.1128/mbio.00419-13

Cited by 70 publications

(92 citation statements)

References 48 publications

(62 reference statements)

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“…36 Other stress-related genes include the small regulatory RNA genes rsmY and rsmZ, the expression of which are essential to enhance population density under environmental stress, 37 and also for biofilm formation. 38 In this study, we observed a significantly reduced expression of the rsmZ gene in AgCNT-treated samples and an upregulation in gentamicin-treated samples. A study has shown that upregulation of these regulatory RNAs resulted in more biofilm formation, by increasing expression of the QS gene lasR.…”

Section: Discussionmentioning

confidence: 52%

Silver-coated carbon nanotubes downregulate the expression of Pseudomonas aeruginosa virulence genes: a potential mechanism for their antimicrobial effect

Dosunmu¹,

Chaudhari²,

Singh³

et al. 2015

IJN

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The antimicrobial activity of silver-coated carbon nanotubes (AgCNTs) and their potential mode of action against mucoid and nonmucoid strains of Pseudomonas aeruginosa was investigated in vitro. The results showed that AgCNTs exhibited antimicrobial activity against both strains with minimum inhibitory concentrations of approximately 8 µg/mL, indicating a high sensitivity of P. aeruginosa to AgCNTs. AgCNTs were also bactericidal against both strains at the same minimum inhibitory concentration. Scanning and transmission electron-microscopy studies further revealed that a majority of the cells treated with AgCNTs transformed from smooth rod-shape morphology to disintegrated cells with broken/damaged membranes, resulting in leakage of cytoplasmic contents to produce ghost cells. The molecular effects of AgCNTs on P. aeruginosa genes involved in virulence and pathogenicity, stress response, and efflux pumps were evaluated for changes in their expression. Quantitative real-time PCR (qRT-PCR) showed that after exposure to AgCNTs, the expression levels of the rpoS , rsmZ , and oprD genes were significantly downregulated in both strains of P. aeruginosa compared to the untreated samples. These results suggest that the mechanism of action of AgCNTs may be attributed to their effect on cell-membrane integrity, downregulation of virulence-gene expression, and induction of general and oxidative stress in P. aeruginosa .

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Section: Discussionmentioning

confidence: 52%

Silver-coated carbon nanotubes downregulate the expression of Pseudomonas aeruginosa virulence genes: a potential mechanism for their antimicrobial effect

Dosunmu¹,

Chaudhari²,

Singh³

et al. 2015

IJN

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“…Therefore, SuhB may control the rates of peptide chain elongation and protein folding [42]. In contrast, the SuhB homolog of P. aeruginosa plays an important role in pathogenesis to control the genes required for acute and chronic infection [47]. Burkholderia cepacia SuhB is required for the secretion of proteins associated with motility and biofilm formation [48], suggesting that the physiological functions of SuhB homologs are complex, which may be true for B. subtilis YktC.…”

Section: Discussionmentioning

confidence: 99%

Bacillus subtilis 5′-nucleotidases with various functions and substrate specificities

et al. 2016

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BackgroundIn Escherichia coli, nagD, yrfG, yjjG, yieH, yigL, surE, and yfbR encode 5′-nucleotidases that hydrolyze the phosphate group of 5′-nucleotides. In Bacillus subtilis, genes encoding 5′-nucleotidase have remained to be identified.ResultsWe found that B. subtilis ycsE, araL, yutF, ysaA, and yqeG show suggestive similarities to nagD. Here, we expressed them in E. coli to purify the respective His6-tagged proteins. YcsE exhibited significant 5′-nucleotidase activity with a broader specificity, whereas the other four enzymes had rather weak but suggestive activities with various capacities and substrate specificities. In contrast, B. subtilis yktC shares high similarity with E. coli suhB encoding an inositol monophosphatase. YktC exhibited inositol monophosphatase activity as well as 5′-nucleotidase activity preferential for GMP and IMP. The ycsE, yktC, and yqeG genes are induced by oxidative stress and were dispensable, although yqeG was required to maintain normal growth on solid medium. In the presence of diamide, only mutants lacking yktC exhibited enhanced growth defects, whereas the other mutants without ycsE or yqeG did not.ConclusionsAccordingly, in B. subtilis, at least YcsE and YktC acted as major 5′-nucleotidases and the four minor enzymes might function when the intracellular concentrations of substrates are sufficiently high. In addition, YktC is involved in resistance to oxidative stress caused by diamide, while YqeG is necessary for normal colony formation on solid medium.Electronic supplementary materialThe online version of this article (doi:10.1186/s12866-016-0866-5) contains supplementary material, which is available to authorized users.

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“…It seems plausible that the ribosomal access to this region could be enhanced by DeaD. In addition to DeaD, RsmA also stimulates ExsA synthesis at a posttranscriptional level (23,46). Whether DeaD and RsmA activities function independently or are dependent upon one another will be the subject of future studies.…”

Section: Discussionmentioning

confidence: 99%

“…The remainder of this study focuses on gene PA2840, identified by two independent transposon insertion events (Table 2) and recently identified in another mutagenesis screen for regulators of T3SS gene expression (46). PA2840, referred to here as deaD, encodes a homolog of Escherichia coli DeaD and is annotated as a probable ATP-dependent RNA helicase (47).…”

Section: Identification Of Novel Extrinsic Regulators Of T3ss Gene Exmentioning

confidence: 99%

The RNA Helicase DeaD Stimulates ExsA Translation To Promote Expression of the Pseudomonas aeruginosa Type III Secretion System

et al. 2015

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The Pseudomonas aeruginosa type III secretion system (T3SS) is a primary virulence factor important for phagocytic avoidance, disruption of host cell signaling, and host cell cytotoxicity. ExsA is the master regulator of T3SS transcription. The expression, synthesis, and activity of ExsA is tightly regulated by both intrinsic and extrinsic factors. Intrinsic regulation consists of the wellcharacterized ExsECDA partner-switching cascade, while extrinsic factors include global regulators that alter exsA transcription and/or translation. To identify novel extrinsic regulators of ExsA, we conducted a transposon mutagenesis screen in the absence of intrinsic control. Transposon disruptions within gene PA2840, which encodes a homolog of the Escherichia coli RNA-helicase DeaD, significantly reduced T3SS gene expression. Recent studies indicate that E. coli DeaD can promote translation by relieving inhibitory secondary structures within target mRNAs. We report here that PA2840, renamed DeaD, stimulates ExsA synthesis at the posttranscriptional level. Genetic experiments demonstrate that the activity of an exsA translational fusion is reduced in a deaD mutant. In addition, exsA expression in trans fails to restore T3SS gene expression in a deaD mutant. We hypothesized that DeaD relaxes mRNA secondary structure to promote exsA translation and found that altering the mRNA sequence of exsA or the native exsA Shine-Dalgarno sequence relieved the requirement for DeaD in vivo. Finally, we show that purified DeaD promotes ExsA synthesis using in vitro translation assays. Together, these data reveal a novel regulatory mechanism for P. aeruginosa DeaD and add to the complexity of global regulation of T3SS. IMPORTANCEAlthough members of the DEAD box family of RNA helicases are appreciated for their roles in mRNA degradation and ribosome biogenesis, an additional role in gene regulation is now emerging in bacteria. By relaxing secondary structures in mRNAs, DEAD box helicases are now thought to promote translation by enhancing ribosomal recruitment. We identify here an RNA helicase that plays a critical role in promoting ExsA synthesis, the central regulator of the Pseudomonas aeruginosa type III secretion system, and provide additional evidence that DEAD box helicases directly stimulate translation of target genes. The finding that DeaD stimulates exsA translation adds to a growing list of transcriptional and posttranscriptional regulatory mechanisms that control type III gene expression. Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen that expresses a large array of virulence factors to cause both acute and chronic infections (1). P. aeruginosa infections generally initiate as acute infections that can range from self-limiting folliculitis to life-threatening ventilator-associated pneumonia (1). P. aeruginosa utilizes a type III secretion system (T3SS) to promote host cell cytotoxicity and avoid phagocytosis (2, 3). The T3SS is a multiprotein complex that spans the cell envelope and functions by directly ...

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SuhB Is a Regulator of Multiple Virulence Genes and Essential for Pathogenesis of Pseudomonas aeruginosa

Cited by 70 publications

References 48 publications

Silver-coated carbon nanotubes downregulate the expression of Pseudomonas aeruginosa virulence genes: a potential mechanism for their antimicrobial effect

Silver-coated carbon nanotubes downregulate the expression of Pseudomonas aeruginosa virulence genes: a potential mechanism for their antimicrobial effect

Bacillus subtilis 5′-nucleotidases with various functions and substrate specificities

The RNA Helicase DeaD Stimulates ExsA Translation To Promote Expression of the Pseudomonas aeruginosa Type III Secretion System

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