scholarly journals Comparative Systems Biology Analysis To Study the Mode of Action of the Isothiocyanate Compound Iberin on Pseudomonas aeruginosa

2014 ◽  
Vol 58 (11) ◽  
pp. 6648-6659 ◽  
Author(s):  
Sean Yang-Yi Tan ◽  
Yang Liu ◽  
Song Lin Chua ◽  
Rebecca Munk Vejborg ◽  
Tim Holm Jakobsen ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Systems Biology ◽  
Rna Sequencing ◽  
Virulence Factor ◽  
Content Type ◽  
Factor Expression ◽  
Small Regulatory Rnas ◽  
Regulatory Rnas ◽  
The Impact ◽  
Comparative Systems

ABSTRACTFood is now recognized as a natural resource of novel antimicrobial agents, including those that target the virulence mechanisms of bacterial pathogens. Iberin, an isothiocyanate compound from horseradish, was recently identified as a quorum-sensing inhibitor (QSI) of the bacterial pathogenPseudomonas aeruginosa. In this study, we used a comparative systems biology approach to unravel the molecular mechanisms of the effects of iberin on QS and virulence factor expression ofP. aeruginosa. Our study shows that the two systems biology methods used (i.e., RNA sequencing and proteomics) complement each other and provide a thorough overview of the impact of iberin onP. aeruginosa. RNA sequencing-based transcriptomics showed that iberin inhibits the expression of the GacA-dependent small regulatory RNAs RsmY and RsmZ; this was verified by usinggfp-based transcriptional reporter fusions with thersmYorrsmZpromoter regions. Isobaric tags for relative and absolute quantitation (iTRAQ) proteomics showed that iberin reduces the abundance of the LadS protein, an activator of GacS. Taken together, the findings suggest that the mode of QS inhibition in iberin is through downregulation of the Gac/Rsm QS network, which in turn leads to the repression of QS-regulated virulence factors, such as pyoverdine, chitinase, and protease IV. Lastly, as expected from the observed repression of small regulatory RNA synthesis, we also show that iberin effectively reduces biofilm formation. This suggests that small regulatory RNAs might serve as potential targets in the future development of therapies against pathogens that use QS for controlling virulence factor expression and assume the biofilm mode of growth in the process of causing disease.

scholarly journals TheprrF-Encoded Small Regulatory RNAs Are Required for Iron Homeostasis and Virulence of Pseudomonas aeruginosa

2014 ◽  
Vol 83 (3) ◽  
pp. 863-875 ◽  
Author(s):  
Alexandria A. Reinhart ◽  
Daniel A. Powell ◽  
Angela T. Nguyen ◽  
Maura O'Neill ◽  
Louise Djapgne ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Iron Homeostasis ◽  
Opportunistic Pathogen ◽  
Wild Type ◽  
Content Type ◽  
Genes Encoding ◽  
Small Regulatory Rnas ◽  
Regulatory Rnas ◽  
Heme Regulation ◽  
Heme Binding Protein

Pseudomonas aeruginosais an opportunistic pathogen that requires iron to cause infection, but it also must regulate the uptake of iron to avoid iron toxicity. The iron-responsive PrrF1 and PrrF2 small regulatory RNAs (sRNAs) are part ofP. aeruginosa'siron regulatory network and affect the expression of at least 50 genes encoding iron-containing proteins. The genes encoding the PrrF1 and PrrF2 sRNAs are encoded in tandem inP. aeruginosa, allowing for the expression of a distinct, heme-responsive sRNA named PrrH that appears to regulate genes involved in heme metabolism. Using a combination of growth, mass spectrometry, and gene expression analysis, we showed that the ΔprrF1,2mutant, which lacks expression of the PrrF and PrrH sRNAs, is defective for both iron and heme homeostasis. We also identifiedphuS, encoding a heme binding protein involved in heme acquisition, andvreR, encoding a previously identified regulator ofP. aeruginosavirulence genes, as novel targets ofprrF-mediated heme regulation. Finally, we showed that theprrFlocus encoding the PrrF and PrrH sRNAs is required forP. aeruginosavirulence in a murine model of acute lung infection. Moreover, we showed that inoculation with a ΔprrF1,2deletion mutant protects against future challenge with wild-typeP. aeruginosa. Combined, these data demonstrate that theprrF-encoded sRNAs are critical regulators ofP. aeruginosavirulence.

scholarly journals Transcriptional Response of Mucoid Pseudomonas aeruginosa to Human Respiratory Mucus

mBio ◽  
2012 ◽  
Vol 3 (6) ◽  
Author(s):  
V. Cattoir ◽  
G. Narasimhan ◽  
D. Skurnik ◽  
H. Aschard ◽  
D. Roux ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Opportunistic Pathogen ◽  
Secretion System ◽  
Type Vi Secretion System ◽  
Transcript Levels ◽  
Content Type ◽  
Type Vi Secretion ◽  
Small Regulatory Rnas ◽  
Regulatory Rnas

ABSTRACTAdaptation of bacterial pathogens to a host can lead to the selection and accumulation of specific mutations in their genomes with profound effects on the overall physiology and virulence of the organisms. The opportunistic pathogenPseudomonas aeruginosais capable of colonizing the respiratory tract of individuals with cystic fibrosis (CF), where it undergoes evolution to optimize survival as a persistent chronic human colonizer. The transcriptome of a host-adapted, alginate-overproducing isolate from a CF patient was determined following growth of the bacteria in the presence of human respiratory mucus. This stable mucoid strain responded to a number of regulatory inputs from the mucus, resulting in an unexpected repression of alginate production. Mucus in the medium also induced the production of catalases and additional peroxide-detoxifying enzymes and caused reorganization of pathways of energy generation. A specific antibacterial type VI secretion system was also induced in mucus-grown cells. Finally, a group of small regulatory RNAs was identified and a fraction of these were mucus regulated. This report provides a snapshot of responses in a pathogen adapted to a human host through assimilation of regulatory signals from tissues, optimizing its long-term survival potential.IMPORTANCEThe basis for chronic colonization of patients with cystic fibrosis (CF) by the opportunistic pathogenPseudomonas aeruginosacontinues to represent a challenging problem for basic scientists and clinicians. In this study, the host-adapted, alginate-overproducingPseudomonas aeruginosa2192 strain was used to assess the changes in its transcript levels following growth in respiratory CF mucus. Several significant and unexpected discoveries were made: (i) although the alginate overproduction in strain 2192 was caused by a stable mutation, a mucus-derived signal caused reduction in the transcript levels of alginate biosynthetic genes; (ii) mucus activated the expression of the type VI secretion system, a mechanism for killing of other bacteria in a mixed population; (iii) expression of a number of genes involved in respiration was altered; and (iv) several small regulatory RNAs were identified, some being mucus regulated. This work highlights the strong influence of the host environment in shaping bacterial survival strategies.

scholarly journals Proteomic Analysis of thePseudomonas aeruginosaIron Starvation Response Reveals PrrF Small Regulatory RNA-Dependent Iron Regulation of Twitching Motility, Amino Acid Metabolism, and Zinc Homeostasis Proteins

2019 ◽  
Vol 201 (12) ◽  
Author(s):  
Cassandra E. Nelson ◽  
Weiliang Huang ◽  
Luke K. Brewer ◽  
Angela T. Nguyen ◽  
Maureen A. Kane ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Immune System ◽  
Amino Acid ◽  
Microbial Pathogens ◽  
Twitching Motility ◽  
Iron Starvation ◽  
Starvation Response ◽  
Content Type ◽  
Small Regulatory Rnas ◽  
Regulatory Rnas

ABSTRACTIron is a critical nutrient for most microbial pathogens, and the immune system exploits this requirement by sequestering iron. The opportunistic pathogenPseudomonas aeruginosaexhibits a high requirement for iron yet an exquisite ability to overcome iron deprivation during infection. Upon iron starvation,P. aeruginosainduces the expression of several high-affinity iron acquisition systems, as well as the PrrF small regulatory RNAs (sRNAs) that mediate an iron-sparing response. Here, we used liquid chromatography-tandem mass spectrometry to conduct proteomics of the iron starvation response ofP. aeruginosa. Iron starvation increased levels of multiple proteins involved in amino acid catabolism, providing the capacity for iron-independent entry of carbons into the tricarboxylic acid (TCA) cycle. Proteins involved in sulfur assimilation and cysteine biosynthesis were reduced upon iron starvation, while proteins involved in iron-sulfur cluster biogenesis were increased, highlighting the central role of iron inP. aeruginosametabolism. Iron starvation also resulted in changes in the expression of several zinc-responsive proteins and increased levels of twitching motility proteins. Subsequent analyses provided evidence for the regulation of many of these proteins via posttranscriptional regulatory events, some of which are dependent upon the PrrF sRNAs. Moreover, we showed that iron-regulated twitching motility is partially dependent upon theprrFlocus, highlighting a novel link between the PrrF sRNAs and motility. These findings add to the known impacts of iron starvation inP. aeruginosaand outline potentially novel roles for the PrrF sRNAs in iron homeostasis and pathogenesis.IMPORTANCEIron is central for growth and metabolism of almost all microbial pathogens, and as such, this element is sequestered by the host innate immune system to restrict microbial growth. Here, we used label-free proteomics to investigate thePseudomonas aeruginosairon starvation response, revealing a broad landscape of metabolic and metal homeostasis changes that have not previously been described. We further provide evidence that many of these processes, including twitching motility, are regulated through the iron-responsive PrrF small regulatory RNAs. As such, this study demonstrates the power of proteomics for defining stress responses of microbial pathogens.

scholarly journals Sub-Inhibitory Antibiotic Exposure and Virulence in Pseudomonas aeruginosa

Antibiotics ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1393
Author(s):  
Charlotte Nolan ◽  
Volker Behrends
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Virulence Factor ◽  
Current Knowledge ◽  
In Vitro Assays ◽  
Antibiotic Exposure ◽  
Bacterial Physiology ◽  
Factor Expression ◽  
The Impact

Pseudomonas aeruginosa is a prime opportunistic pathogen, one of the most important causes of hospital-acquired infections and the major cause of morbidity and mortality in cystic fibrosis lung infections. One reason for the bacterium’s pathogenic success is the large array of virulence factors that it can employ. Another is its high degree of intrinsic and acquired resistance to antibiotics. In this review, we first summarise the current knowledge about the regulation of virulence factor expression and production. We then look at the impact of sub-MIC antibiotic exposure and find that the virulence–antibiotic interaction for P. aeruginosa is antibiotic-specific, multifaceted, and complex. Most studies undertaken to date have been in vitro assays in batch culture systems, involving short-term (<24 h) antibiotic exposure. Therefore, we discuss the importance of long-term, in vivo-mimicking models for future work, particularly highlighting the need to account for bacterial physiology, which by extension governs both virulence factor expression and antibiotic tolerance/resistance.

scholarly journals Exogenous Alginate Protects Staphylococcus aureus from Killing by Pseudomonas aeruginosa

2019 ◽  
Vol 202 (8) ◽  
Author(s):  
Courtney E. Price ◽  
Dustin G. Brown ◽  
Dominique H. Limoli ◽  
Vanessa V. Phelan ◽  
George A. O’Toole
Keyword(s):  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Physical Space ◽  
Late Time ◽  
Protective Effects ◽  
Content Type ◽  
Alginate Production ◽  
The Impact

ABSTRACT Cystic fibrosis (CF) patients chronically infected with both Pseudomonas aeruginosa and Staphylococcus aureus have worse health outcomes than patients who are monoinfected with either P. aeruginosa or S. aureus. We showed previously that mucoid strains of P. aeruginosa can coexist with S. aureus in vitro due to the transcriptional downregulation of several toxic exoproducts typically produced by P. aeruginosa, including siderophores, rhamnolipids, and HQNO (2-heptyl-4-hydroxyquinoline N-oxide). Here, we demonstrate that exogenous alginate protects S. aureus from P. aeruginosa in both planktonic and biofilm coculture models under a variety of nutritional conditions. S. aureus protection in the presence of exogenous alginate is due to the transcriptional downregulation of pvdA, a gene required for the production of the iron-scavenging siderophore pyoverdine as well as the downregulation of the PQS (Pseudomonas quinolone signal) (2-heptyl-3,4-dihydroxyquinoline) quorum sensing system. The impact of exogenous alginate is independent of endogenous alginate production. We further demonstrate that coculture of mucoid P. aeruginosa with nonmucoid P. aeruginosa strains can mitigate the killing of S. aureus by the nonmucoid strain of P. aeruginosa, indicating that the mechanism that we describe here may function in vivo in the context of mixed infections. Finally, we investigated a panel of mucoid clinical isolates that retain the ability to kill S. aureus at late time points and show that each strain has a unique expression profile, indicating that mucoid isolates can overcome the S. aureus-protective effects of mucoidy in a strain-specific manner. IMPORTANCE CF patients are chronically infected by polymicrobial communities. The two dominant bacterial pathogens that infect the lungs of CF patients are P. aeruginosa and S. aureus, with ∼30% of patients coinfected by both species. Such coinfected individuals have worse outcomes than monoinfected patients, and both species persist within the same physical space. A variety of host and environmental factors have been demonstrated to promote P. aeruginosa-S. aureus coexistence, despite evidence that P. aeruginosa kills S. aureus when these organisms are cocultured in vitro. Thus, a better understanding of P. aeruginosa-S. aureus interactions, particularly mechanisms by which these microorganisms are able to coexist in proximal physical space, will lead to better-informed treatments for chronic polymicrobial infections.

scholarly journals Changes in the Use of Broad-Spectrum Antibiotics after Cefepime Shortage: a Time Series Analysis

2011 ◽  
Vol 56 (2) ◽  
pp. 989-994 ◽  
Author(s):  
C. Plüss-Suard ◽  
A. Pannatier ◽  
C. Ruffieux ◽  
A. Kronenberg ◽  
K. Mühlemann ◽  
...  
Keyword(s):  
Time Series ◽  
Pseudomonas Aeruginosa ◽  
Broad Spectrum ◽  
Interrupted Time Series ◽  
Antibiotic Policy ◽  
Content Type ◽  
Broad Spectrum Antibiotics ◽  
Before And After ◽  
Alternative Antibiotic ◽  
The Impact

ABSTRACTThe original cefepime product was withdrawn from the Swiss market in January 2007 and replaced by a generic 10 months later. The goals of the study were to assess the impact of this cefepime shortage on the use and costs of alternative broad-spectrum antibiotics, on antibiotic policy, and on resistance ofPseudomonas aeruginosatoward carbapenems, ceftazidime, and piperacillin-tazobactam. A generalized regression-based interrupted time series model assessed how much the shortage changed the monthly use and costs of cefepime and of selected alternative broad-spectrum antibiotics (ceftazidime, imipenem-cilastatin, meropenem, piperacillin-tazobactam) in 15 Swiss acute care hospitals from January 2005 to December 2008. Resistance ofP. aeruginosawas compared before and after the cefepime shortage. There was a statistically significant increase in the consumption of piperacillin-tazobactam in hospitals with definitive interruption of cefepime supply and of meropenem in hospitals with transient interruption of cefepime supply. Consumption of each alternative antibiotic tended to increase during the cefepime shortage and to decrease when the cefepime generic was released. These shifts were associated with significantly higher overall costs. There was no significant change in hospitals with uninterrupted cefepime supply. The alternative antibiotics for which an increase in consumption showed the strongest association with a progression of resistance were the carbapenems. The use of alternative antibiotics after cefepime withdrawal was associated with a significant increase in piperacillin-tazobactam and meropenem use and in overall costs and with a decrease in susceptibility ofP. aeruginosain hospitals. This warrants caution with regard to shortages and withdrawals of antibiotics.

scholarly journals Activity of Ceftazidime-Avibactam against Fluoroquinolone-Resistant Enterobacteriaceae and Pseudomonas aeruginosa

2015 ◽  
Vol 59 (6) ◽  
pp. 3059-3065 ◽  
Author(s):  
C. Pitart ◽  
F. Marco ◽  
T. A. Keating ◽  
W. W. Nichols ◽  
J. Vila
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Resistant Mutant ◽  
Fluoroquinolone Resistance ◽  
Cross Resistance ◽  
Content Type ◽  
E Coli ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
The Impact

ABSTRACTCeftazidime-avibactam and comparator antibiotics were tested by the broth microdilution method against 200Enterobacteriaceaeand 25Pseudomonas aeruginosastrains resistant to fluoroquinolones (including strains with the extended-spectrum β-lactamase [ESBL] phenotype and ceftazidime-resistant strains) collected from our institution. The MICs and mechanisms of resistance to fluoroquinolone were also studied. Ninety-nine percent of fluoroquinolone-resistantEnterobacteriaceaestrains were inhibited at a ceftazidime-avibactam MIC of ≤4 mg/liter (using the susceptible CLSI breakpoint for ceftazidime alone as a reference). Ceftazidime-avibactam was very active against ESBLEscherichia coli(MIC90of 0.25 mg/liter), ESBLKlebsiella pneumoniae(MIC90of 0.5 mg/liter), ceftazidime-resistant AmpC-producing species (MIC90of 1 mg/liter), non-ESBLE. coli(MIC90of ≤0.125 mg/liter), non-ESBLK. pneumoniae(MIC90of 0.25 mg/liter), and ceftazidime-nonresistant AmpC-producing species (MIC90of ≤0.5 mg/liter). Ninety-six percent of fluoroquinolone-resistantP. aeruginosastrains were inhibited at a ceftazidime-avibactam MIC of ≤8 mg/liter (using the susceptible CLSI breakpoint for ceftazidime alone as a reference), with a MIC90of 8 mg/liter. Additionally, fluoroquinolone-resistant mutants from each species tested were obtainedin vitrofrom two strains, one susceptible to ceftazidime and the other a β-lactamase producer with a high MIC against ceftazidime but susceptible to ceftazidime-avibactam. Thereby, the impact of fluoroquinolone resistance on the activity of ceftazidime-avibactam could be assessed. The MIC90values of ceftazidime-avibactam for the fluoroquinolone-resistant mutant strains ofEnterobacteriaceaeandP. aeruginosawere ≤4 mg/liter and ≤8 mg/liter, respectively. We conclude that the presence of fluoroquinolone resistance does not affectEnterobacteriaceaeandP. aeruginosasusceptibility to ceftazidime-avibactam; that is, there is no cross-resistance.

scholarly journals Predictors of Mortality in Bloodstream Infections Caused by Pseudomonas aeruginosa and Impact of Antimicrobial Resistance and Bacterial Virulence

2019 ◽  
Vol 64 (2) ◽  
Author(s):  
Raúl Recio ◽  
Mikel Mancheño ◽  
Esther Viedma ◽  
Jennifer Villa ◽  
María Ángeles Orellana ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Antimicrobial Resistance ◽  
Multivariate Logistic Regression Analysis ◽  
Empirical Therapy ◽  
Bloodstream Infections ◽  
Multivariate Logistic Regression ◽  
Related Factors ◽  
Content Type ◽  
Crude Mortality ◽  
The Impact

ABSTRACT Whether multidrug resistance (MDR) is associated with mortality in patients with Pseudomonas aeruginosa bloodstream infections (BSI) remains controversial. Here, we explored the prognostic factors of P. aeruginosa BSI with emphasis on antimicrobial resistance and virulence. All P. aeruginosa BSI episodes in a 5-year period were retrospectively analyzed. The impact in early (5-day) and late (30-day) crude mortality of host, antibiotic treatment, and pathogen factors was assessed by multivariate logistic regression analysis. Of 243 episodes, 93 (38.3%) were caused by MDR-PA. Crude 5-day (20%) and 30-day (33%) mortality was more frequent in patients with MDR-PA (34.4% versus 11.3%, P < 0.001 and 52.7% versus 21.3%, P < 0.001, respectively). Early mortality was associated with neutropenia (adjusted odds ratio [aOR], 9.21; 95% confidence interval [CI], 3.40 to 24.9; P < 0.001), increased Pitt score (aOR, 2.42; 95% CI, 1.34 to 4.36; P = 0.003), respiratory source (aOR, 3.23; 95% CI,2.01 to 5.16; P < 0.001), inadequate empirical therapy (aOR, 4.57; 95% CI, 1.59 to 13.1; P = 0.005), shorter time to positivity of blood culture (aOR, 0.88; 95% CI, 0.80 to 0.97; P = 0.010), an exoU-positive genotype (aOR, 3.58; 95% CI, 1.31 to 9.79; P = 0.013), and the O11 serotype (aOR, 3.64; 95% CI, 1.20 to 11.1; P = 0.022). These risk factors were similarly identified for late mortality, along with an MDR phenotype (aOR, 2.18; 95% CI, 1.04 to 4.58; P = 0.040). Moreover, the O11 serotype (15.2%, 37/243) was common among MDR (78.4%, 29/37) and exoU-positive (89.2%, 33/37) strains. Besides relevant clinical variables and inadequate empirical therapy, pathogen-related factors such as an MDR phenotype, an exoU-positive genotype, and the O11 serotype adversely affect the outcome of P. aeruginosa BSI.

scholarly journals Light-Mediated Decreases in Cyclic di-GMP Levels Inhibit Structure Formation in Pseudomonas aeruginosa Biofilms

2020 ◽  
Vol 202 (14) ◽  
Author(s):  
Lisa Juliane Kahl ◽  
Alexa Price-Whelan ◽  
Lars E. P. Dietrich
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Bacterial Infections ◽  
Prolonged Exposure ◽  
Light Exposure ◽  
Research Attention ◽  
Content Type ◽  
Dependent Inhibition ◽  
Matrix Production ◽  
Biofilm Development ◽  
The Impact

ABSTRACT Light is known to trigger regulatory responses in diverse organisms, including slime molds, animals, plants, and phototrophic bacteria. However, light-dependent processes in nonphototrophic bacteria, and those of pathogens in particular, have received comparatively little research attention. In this study, we examined the impact of light on multicellular development in Pseudomonas aeruginosa, a leading cause of biofilm-based bacterial infections. We grew P. aeruginosa strain PA14 in a colony morphology assay and found that growth under prolonged exposure to low-intensity blue light inhibited biofilm matrix production and thereby the formation of vertical biofilm structures (i.e., “wrinkles”). Light-dependent inhibition of biofilm wrinkling was correlated with low levels of cyclic di-GMP (c-di-GMP), consistent with the role of this signal in stimulating matrix production. A screen of enzymes with the potential to catalyze c-di-GMP synthesis or degradation identified c-di-GMP phosphodiesterases that contribute to light-dependent inhibition of biofilm wrinkling. One of these, RmcA, was previously characterized by our group for its role in mediating the effect of redox-active P. aeruginosa metabolites called phenazines on biofilm wrinkle formation. Our results suggest that an RmcA sensory domain that is predicted to bind a flavin cofactor is involved in light-dependent inhibition of wrinkling. Together, these findings indicate that P. aeruginosa integrates information about light exposure and redox state in its regulation of biofilm development. IMPORTANCE Light exposure tunes circadian rhythms, which modulate the immune response and affect susceptibility to infection in plants and animals. Though molecular responses to light are defined for model plant and animal hosts, analogous pathways that function in bacterial pathogens are understudied. We examined the response to light exposure in biofilms (matrix-encased multicellular assemblages) of the nonphotosynthetic bacterium Pseudomonas aeruginosa. We found that light at intensities that are not harmful to human cells inhibited biofilm maturation via effects on cellular signals. Because biofilm formation is a critical factor in many types of P. aeruginosa infections, including burn wound infections that may be exposed to light, these effects could be relevant for pathogenicity.

scholarly journals RNase E Promotes Expression of Type III Secretion System Genes in Pseudomonas aeruginosa

2019 ◽  
Vol 201 (22) ◽  
Author(s):  
Josh S. Sharp ◽  
Arne Rietsch ◽  
Simon L. Dove
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Type Iii Secretion ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Effector Proteins ◽  
Host Cells ◽  
Rnase E ◽  
Content Type ◽  
Type Iii ◽  
Small Regulatory Rnas

ABSTRACT Pseudomonas aeruginosa is an important opportunistic pathogen that employs a type III secretion system (T3SS) to inject effector proteins into host cells. Using a protein depletion system, we show that the endoribonuclease RNase E positively regulates expression of the T3SS genes. We also present evidence that RNase E antagonizes the expression of genes of the type VI secretion system and limits biofilm production in P. aeruginosa. Thus, RNase E, which is thought to be the principal endoribonuclease involved in the initiation of RNA degradation in P. aeruginosa, plays a key role in controlling the production of factors involved in both acute and chronic stages of infection. Although the posttranscriptional regulator RsmA is also known to positively regulate expression of the T3SS genes, we find that RNase E does not appreciably influence the abundance of RsmA in P. aeruginosa. Moreover, we show that RNase E still exerts its effects on T3SS gene expression in cells lacking all four of the key small regulatory RNAs that function by sequestering RsmA. IMPORTANCE The type III secretion system (T3SS) is a protein complex produced by many Gram-negative pathogens. It is capable of injecting effector proteins into host cells that can manipulate cell metabolism and have toxic effects. Understanding how the T3SS is regulated is important in understanding the pathogenesis of bacteria with such systems. Here, we show that RNase E, which is typically thought of as a global regulator of RNA stability, plays a role in regulating the T3SS in Pseudomonas aeruginosa. Depleting RNase E results in the loss of T3SS gene expression as well as a concomitant increase in biofilm formation. These observations are reminiscent of the phenotypes associated with the loss of activity of the posttranscriptional regulator RsmA. However, RNase E-mediated regulation of these systems does not involve changes in the abundance of RsmA and is independent of the known small regulatory RNAs that modulate RsmA activity.

Sign in / Sign up

Export Citation Format

Share Document