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

mBio ◽  
2013 ◽  
Vol 4 (6) ◽  
Author(s):  
Kewei Li ◽  
Chang Xu ◽  
Yongxin Jin ◽  
Ziyu Sun ◽  
Chang Liu ◽  
...  
Keyword(s):  
Gene Expression ◽  
Pseudomonas Aeruginosa ◽  
Virulence Factors ◽  
Biofilm Formation ◽  
Regulatory Networks ◽  
Virulence Genes ◽  
Chronic Infections ◽  
Content Type ◽  
Factors Associated ◽  
Acute Infections

ABSTRACTDuring initial colonization and chronic infection, pathogenic bacteria encounter distinct host environments. Adjusting gene expression accordingly is essential for the pathogenesis.Pseudomonas aeruginosahas evolved complicated regulatory networks to regulate different sets of virulence factors to facilitate colonization and persistence. The type III secretion system (T3SS) and motility are associated with acute infections, while biofilm formation and the type VI secretion system (T6SS) are associated with chronic persistence. To identify novel regulatory genes required for pathogenesis, we screened aP. aeruginosatransposon (Tn) insertion library and foundsuhBto be an essential gene for the T3SS gene expression. The expression ofsuhBwas upregulated in a mouse acute lung infection model, and loss ofsuhBresulted in avirulence. Suppression of T3SS gene expression in thesuhBmutant is linked to a defective translation of the T3SS master regulator, ExsA. Further studies demonstrated thatsuhBmutation led to the upregulation of GacA and its downstream small RNAs, RsmY and RsmZ, triggering T6SS expression and biofilm formation while inhibiting the T3SS. Our results demonstrate that anin vivo-inducible gene,suhB, reciprocally regulates genes associated with acute and chronic infections and plays an essential role in the pathogenesis ofP. aeruginosa.IMPORTANCEA variety of bacterial pathogens, such asPseudomonas aeruginosa, cause acute and chronic infections in humans. During infections, pathogens produce different sets of virulence genes for colonization, tissue damage, and dissemination and for countering host immune responses. Complex regulatory networks control the delicate tuning of gene expression in response to host environments to enable the survival and growth of invading pathogens. Here we identifiedsuhBas a critical gene for the regulation of virulence factors inP. aeruginosa. The expression ofsuhBwas upregulated during acute infection in an animal model, and mutation ofsuhBrenderedP. aeruginosaavirulent. Moreover, we demonstrate that SuhB is required for the activation of virulence factors associated with acute infections while suppressing virulence factors associated with chronic infections. Our report provides new insights into the multilayered regulatory network of virulence genes inP. aeruginosa.

scholarly journals Genome Sequences of Two Pseudomonas aeruginosa Isolates with Defects in Type III Secretion System Gene Expression from a Chronic Ankle Wound Infection

2021 ◽  
Author(s):  
Sardar Karash ◽  
Robert Nordell ◽  
Egon A. Ozer ◽  
Timothy L. Yahr
Keyword(s):  
Gene Expression ◽  
Pseudomonas Aeruginosa ◽  
Type Iii Secretion ◽  
Biofilm Formation ◽  
Secretion System ◽  
Chronic Infections ◽  
Genome Sequences ◽  
Content Type ◽  
Chronic Colonization ◽  
Host Tolerance

A common feature of microorganisms that cause chronic infections is a stealthy lifestyle that promotes immune avoidance and host tolerance. During chronic colonization of cystic fibrosis (CF) patients, Pseudomonas aeruginosa acquires numerous adaptations that include reduced expression of some factors, such as motility, O antigen, and the T3SS, and increased expression of other traits, such as biofilm formation.

scholarly journals Fluorescence-Based Reporter for Gauging Cyclic Di-GMP Levels in Pseudomonas aeruginosa

2012 ◽  
Vol 78 (15) ◽  
pp. 5060-5069 ◽  
Author(s):  
Morten T. Rybtke ◽  
Bradley R. Borlee ◽  
Keiji Murakami ◽  
Yasuhiko Irie ◽  
Morten Hentzer ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Biofilm Formation ◽  
Fluorescent Protein ◽  
Subsequent Development ◽  
Cellular Level ◽  
Host Immune System ◽  
Chronic Infections ◽  
Content Type ◽  
Genes Encoding ◽  
Green Fluorescent

ABSTRACTThe increased tolerance toward the host immune system and antibiotics displayed by biofilm-formingPseudomonas aeruginosaand other bacteria in chronic infections such as cystic fibrosis bronchopneumonia is of major concern. Targeting of biofilm formation is believed to be a key aspect in the development of novel antipathogenic drugs that can augment the effect of classic antibiotics by decreasing antimicrobial tolerance. The second messenger cyclic di-GMP is a positive regulator of biofilm formation, and cyclic di-GMP signaling is now regarded as a potential target for the development of antipathogenic compounds. Here we describe the development of fluorescent monitors that can gauge the cellular level of cyclic di-GMP inP. aeruginosa. We have created cyclic di-GMP level reporters by transcriptionally fusing the cyclic di-GMP-responsivecdrApromoter to genes encoding green fluorescent protein. We show that the reporter constructs give a fluorescent readout of the intracellular level of cyclic di-GMP inP. aeruginosastrains with different levels of cyclic di-GMP. Furthermore, we show that the reporters are able to detect increased turnover of cyclic di-GMP mediated by treatment ofP. aeruginosawith the phosphodiesterase inducer nitric oxide. Considering that biofilm formation is a necessity for the subsequent development of a chronic infection and therefore a pathogenicity trait, the reporters display a significant potential for use in the identification of novel antipathogenic compounds targeting cyclic di-GMP signaling, as well as for use in research aiming at understanding the biofilm biology ofP. aeruginosa.

scholarly journals PrtR Homeostasis Contributes to Pseudomonas aeruginosa Pathogenesis and Resistance against Ciprofloxacin

2014 ◽  
Vol 82 (4) ◽  
pp. 1638-1647 ◽  
Author(s):  
Ziyu Sun ◽  
Jing Shi ◽  
Chang Liu ◽  
Yongxin Jin ◽  
Kewei Li ◽  
...  
Keyword(s):  
Gene Expression ◽  
Pseudomonas Aeruginosa ◽  
Bacterial Colonization ◽  
Mrna Level ◽  
Sos Response ◽  
Opportunistic Pathogen ◽  
Host Cells ◽  
Chronic Infections ◽  
Mobility Shift ◽  
Content Type

ABSTRACTPseudomonas aeruginosais an opportunistic pathogen that causes acute and chronic infections in humans. Pyocins are bacteriocins produced byP. aeruginosathat are usually released through lysis of the producer strains. Expression of pyocin genes is negatively regulated by PrtR, which gets cleaved under SOS response, leading to upregulation of pyocin synthetic genes. Previously, we demonstrated that PrtR is required for the expression of type III secretion system (T3SS), which is an important virulence component ofP. aeruginosa. In this study, we demonstrate that mutation inprtRresults in reduced bacterial colonization in a mouse acute pneumonia model. Examination of bacterial and host cells in the bronchoalveolar lavage fluids from infected mice revealed that expression of PrtR is induced by reactive oxygen species (ROS) released by neutrophils. We further demonstrate that treatment with hydrogen peroxide or ciprofloxacin, known to induce the SOS response and pyocin production, resulted in an elevated PrtR mRNA level. Overexpression of PrtR by atacpromoter repressed the endogenousprtRpromoter activity, and electrophoretic mobility shift assay revealed that PrtR binds to its own promoter, suggesting an autorepressive mechanism of regulation. A high level of PrtR expressed from a plasmid resulted in increased T3SS gene expression during infection and higher resistance against ciprofloxacin. Overall, our results suggest that the autorepression of PrtR contributes to the maintenance of a relatively stable level of PrtR, which is permissive to T3SS gene expression in the presence of ROS while increasing bacterial tolerance to stresses, such as ciprofloxacin, by limiting pyocin production.

scholarly journals Pseudomonas aeruginosa AlgU Contributes to Posttranscriptional Activity by IncreasingrsmAExpression in amucA22Strain

2016 ◽  
Vol 198 (13) ◽  
pp. 1812-1826 ◽  
Author(s):  
Sean D. Stacey ◽  
Christopher L. Pritchett
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Biofilm Formation ◽  
Laboratory Strain ◽  
Immunocompromised Patients ◽  
Chronic Infections ◽  
Rnase Protection ◽  
Content Type ◽  
Mutant Strains ◽  
Life Threatening ◽  
Severe Infections

ABSTRACTPseudomonas aeruginosathrives in multiple environments and is capable of causing life-threatening infections in immunocompromised patients. RsmA is a posttranscriptional regulator that controls virulence factor production and biofilm formation. In this study, we investigated the expression and activity ofrsmAand the protein that it encodes, RsmA, inP. aeruginosamucAmutant strains, which are common in chronic infections. We determined that AlgU regulates a previously unknownrsmApromoter inP. aeruginosa. Western blot analysis confirmed that AlgU controlsrsmAexpression in both a laboratory strain and a clinical isolate. RNase protection assays confirmed the presence of tworsmAtranscripts and suggest that RpoS and AlgU regulatersmAexpression. Due to the increased amounts of RsmA inmucAmutant strains, a translational leader fusion of the RsmA target,tssA1, was constructed and tested inmucA,algU,retS,gacA, andrsmAmutant backgrounds to examine posttranscriptional activity. From these studies, we determined that RsmA is active inmucA22mutants, suggesting a role for RsmA inmucAmutant strains. Taken together, we have demonstrated that AlgU controlsrsmAtranscription and is responsible for RsmA activity inmucAmutant strains. We propose that RsmA is active inP. aeruginosamucAmutant strains and that RsmA also plays a role in chronic infections.IMPORTANCEP. aeruginosacauses severe infections in immunocompromised patients. The posttranscriptional regulator RsmA is known to control virulence and biofilm formation. We identify a newrsmApromoter and determine that AlgU is important in the control ofrsmAexpression. MutantmucAstrains that are considered mucoid were used to confirm increasedrsmAexpression from the AlgU promoter. We demonstrate, for the first time, that there is RsmA activity in mucoidP. aeruginosastrains. Our work suggests that RsmA may play a role during chronic infections as well as acute infections.

scholarly journals Study of quorum-sensing LasR and RhlR genes and their dependent virulence factors in Pseudomonas aeruginosa isolates from infected burn wounds

2021 ◽  
Vol 3 (3) ◽  
Author(s):  
Aya Ahmad Elnegery ◽  
Wafaa Kamel Mowafy ◽  
Tarek Ahmed Zahra ◽  
Noha Tharwat Abou El-Khier
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Proteolytic Activity ◽  
Virulence Factors ◽  
Biofilm Formation ◽  
Type Species ◽  
Assay Method ◽  
Content Type ◽  
Burn Wounds ◽  
Link Type

Background. Pseudomonas aeruginosa (P. aeruginosa) is an opportunistic pathogen responsible for burn-wound infection. High incidence, infection severity and increasing resistance characterize P. aeruginosa -induced burn infection. Purpose. To estimate quorum-sensing (QS)-dependent virulence factors of P. aeruginosa isolates from burn wounds and correlate it to the presence of QS genes. Methods. A cross-sectional descriptive study included 50 P . aeruginosa isolates from burn patients in Mansoura University Plastic and Burn Hospital, Egypt. Antibiotic sensitivity tests were done. All isolates were tested for their ability to produce biofilm using a micro-titration assay method. Protease, pyocyanin and rhamnolipid virulence factors were determined using skimmed milk agar, King’s A medium and CTAB agar test, respectively. The identity of QS lasR and rhlR genes was confirmed using PCR. Results. In total, 86 % of isolates had proteolytic activity. Production of pyocyanin pigment was manifested in 66 % of isolates. Altogether, 76 % of isolates were rhamnolipid producers. Biofilm formation was detected in 96 % of isolates. QS lasR and rhlR genes were harboured by nearly all isolates except three isolates were negative for both lasR and rhlR genes and two isolates were positive for lasR gene and negative for rhlR gene. Forty-nine isolates were considered as extremely QS-proficient strains as they produced QS-dependent virulence factors. In contrast, one isolate was a QS deficient strain. Conclusions. QS affects P. aeruginosa virulence-factor production and biofilm in burn wounds. Isolates containing lasR and rhlR seem to be a crucial regulator of virulence factors and biofilm formation in P. aeruginosa whereas the lasR gene positively regulates biofilm formation, proteolytic activity, pyocyanin production and rhamnolipid biosurfactant synthesis. The QS regulatory RhlR gene affects protease and rhamnolipid production positively.

scholarly journals 2,3-Dihydroxybenzoic Acid-Containing Nanofiber Wound Dressings Inhibit Biofilm Formation by Pseudomonas aeruginosa

2014 ◽  
Vol 58 (4) ◽  
pp. 2098-2104 ◽  
Author(s):  
Jayesh J. Ahire ◽  
Leon M. T. Dicks
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Biofilm Formation ◽  
Iron Chelator ◽  
Wound Dressings ◽  
Tissue Destruction ◽  
Dihydroxybenzoic Acid ◽  
Chronic Infections ◽  
Content Type ◽  
Cell Numbers ◽  
Time Required

ABSTRACTPseudomonas aeruginosaforms biofilms in wounds, which often leads to chronic infections that are difficult to treat with antibiotics. Free iron enhances biofilm formation, delays wound healing, and may even be responsible for persistent inflammation, increased connective tissue destruction, and lipid peroxidation. Exposure ofP. aeruginosaXen 5 to the iron chelator 2,3-dihydroxybenzoic acid (DHBA), electrospun into a nanofiber blend of poly(d,l-lactide) (PDLLA) and poly(ethylene oxide) (PEO), referred to as DF, for 8 h decreased biofilm formation by approximately 75%. This was shown by a drastic decline in cell numbers, from 7.1 log10CFU/ml to 4.8 log10CFU/ml when biofilms were exposed to DF in the presence of 2.0 mM FeCl36H2O. A similar decline in cell numbers was recorded in the presence of 3.0 mM FeCl36H2O and DF. The cells were more mobile in the presence of DHBA, supporting the observation of less biofilm formation at lower iron concentrations. DHBA at MIC levels (1.5 mg/ml) inhibited the growth of strain Xen 5 for at least 24 h. Our findings indicate that DHBA electrospun into nanofibers inhibits cell growth for at least 4 h, which is equivalent to the time required for all DHBA to diffuse from DF. This is the first indication that DF can be developed into a wound dressing to treat topical infections caused byP. aeruginosa.

scholarly journals Involvement of Stress-Related GenespolBandPA14_46880in Biofilm Formation of Pseudomonas aeruginosa

2014 ◽  
Vol 82 (11) ◽  
pp. 4746-4757 ◽  
Author(s):  
Sahar A. Alshalchi ◽  
Gregory G. Anderson
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Biofilm Formation ◽  
Acute Infection ◽  
Regulatory Gene ◽  
Chronic Infections ◽  
Content Type ◽  
Abiotic Surfaces ◽  
Mutant Strains ◽  
In The Wild ◽  
Airway Cells

ABSTRACTChronic infections ofPseudomonas aeruginosaare generally established through production of biofilm. During biofilm formation, production of an extracellular matrix and establishment of a distinct bacterial phenotype make these infections difficult to eradicate. However, biofilm studies have been hampered by the fact that most assays utilize nonliving surfaces as biofilm attachment substrates. In an attempt to better understand the mechanisms behindP. aeruginosabiofilm formation, we performed a genetic screen to identify novel factors involved in biofilm formation on biotic and abiotic surfaces. We found that deletion of genespolBandPA14_46880reduced biofilm formation significantly compared to that in the wild-type strain PA14 in an abiotic biofilm system. In a biotic biofilm model, wherein biofilms form on cultured airway cells, the ΔpolBand ΔPA14_46880strains showed increased cytotoxic killing of the airway cells independent of the total number of bacteria bound. Notably, deletion mutant strains were more resistant to ciprofloxacin treatment. This phenotype was linked to decreased expression ofalgR, an alginate transcriptional regulatory gene, under ciprofloxacin pressure. Moreover, we found that pyocyanin production was increased in planktonic cells of mutant strains. These results indicate that inactivation ofpolBandPA14_46880may inhibit transition ofP. aeruginosafrom a more acute infection lifestyle to the biofilm phenotype. Future investigation of these genes may lead to a better understanding ofP. aeruginosabiofilm formation and chronic biofilm infections.

scholarly journals Signal Sensing and Transduction Are Conserved between the Periplasmic Sensory Domains of BifA and SagS

mSphere ◽  
2019 ◽  
Vol 4 (4) ◽  
Author(s):  
Jozef Dingemans ◽  
Rebecca E. Al-Feghali ◽  
Holger Sondermann ◽  
Karin Sauer
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Biofilm Formation ◽  
Structural Similarity ◽  
Opportunistic Pathogen ◽  
Sequence Conservation ◽  
Sensor Kinase ◽  
Antibiotic Tolerance ◽  
Bacterial Cells ◽  
Chronic Infections ◽  
Content Type

ABSTRACT The hybrid sensor kinase SagS of Pseudomonas aeruginosa plays a key role in the transition from the planktonic to the biofilm mode of growth. Recently, we have shown that distinct sets of residues in its periplasmic HmsP sensory domain are involved in the regulation of biofilm formation or antibiotic tolerance. Interestingly, the HmsP domain of the phosphodiesterase BifA shows great predicted structural similarity to that of SagS, despite moderate sequence conservation and only a number of residues involved in SagS signaling being conserved between both proteins. Based on this observation, we hypothesized that BifA and SagS may use similar mechanisms to sense and transduce signals perceived at their periplasmic HmsP domains and, therefore, may be interchangeable. To test this hypothesis, we constructed SagS hybrids in which the HmsP domain of SagS was replaced by that of BifA (and vice versa) or by the DISMED2 sensory domain of NicD. The SagS-BifA hybrid restored attachment and biofilm formation by the ΔbifA mutant. Likewise, while the NicD-SagS hybrid was nonfunctional, the BifA-SagS hybrid partially restored pathways leading to biofilm formation and antibiotic tolerance in a ΔsagS mutant background. Furthermore, alanine substitution of key residues previously associated with the biofilm formation and antibiotic tolerance pathways of SagS impaired signal transduction by the BifA-SagS hybrid in a similar way to SagS. In conclusion, our data indicate that the nature of the sensory domain is important for proper functionality of the cytoplasmic effector domains and that signal sensing and transduction are likely conserved in SagS and BifA. IMPORTANCE Biofilms have been associated with more than 60% of all recalcitrant and chronic infections and can render bacterial cells up to a thousand times more resistant to antibiotics than planktonic cells. Although it is known that the transition from the planktonic to the biofilm mode of growth involves two-component regulatory systems, increased c-di-GMP levels, and quorum sensing systems among others, the exact signaling events that lead to biofilm formation remain unknown. In the opportunistic pathogen Pseudomonas aeruginosa, the hybrid sensor kinase SagS regulates biofilm formation and antibiotic tolerance through two independent pathways via distinct residues in its periplasmic sensory domain. Interestingly, the sensory domains of SagS and BifA show great predicted structural similarity despite moderate sequence conservation. Here we show that the sensory domains of BifA and SagS are functionally interchangeable and that they use a similar mechanism of signal sensing and transduction, which broadens our understanding of how bacteria perceive and transduce signals when transitioning to the biofilm mode of growth.

scholarly journals Role of Intracellular Proteases in the Antibiotic Resistance, Motility, and Biofilm Formation of Pseudomonas aeruginosa

2011 ◽  
Vol 56 (2) ◽  
pp. 1128-1132 ◽  
Author(s):  
Lucía Fernández ◽  
Elena B. M. Breidenstein ◽  
Diana Song ◽  
Robert E. W. Hancock
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Antibiotic Resistance ◽  
Biofilm Formation ◽  
Regulatory Networks ◽  
Swarming Motility ◽  
Content Type ◽  
Adverse Conditions ◽  
Related Proteins ◽  
Intracellular Proteases

ABSTRACTPseudomonas aeruginosapossesses complex regulatory networks controlling virulence and survival under adverse conditions, including antibiotic pressure, which are interconnected and share common regulatory proteins. Here, we screen a panel of 13 mutants defective in intracellular proteases and demonstrate that, in addition to the known alterations in Lon and AsrA mutants, mutation of three protease-related proteins PfpI, ClpS, and ClpP differentially affected antibiotic resistance, swarming motility, and biofilm formation.

scholarly journals Uncovering the dynamic mechanisms of the Pseudomonas aeruginosa quorum sensing and virulence networks using Boolean modelling

2019 ◽  
Author(s):  
Manuel Banzhaf ◽  
Osbaldo Resendis-Antonio ◽  
M. Lisandra Zepeda-Mendoza
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Virulence Factors ◽  
Regulatory Networks ◽  
Opportunistic Pathogen ◽  
Resistance Mechanisms ◽  
System Level ◽  
Clear Understanding ◽  
Chronic Infections ◽  
Modelling Framework

AbstractIntroductionPseudomonas aeruginosa is an opportunistic pathogen with an extraordinary metabolic adaptability and a large repertoire of virulence factors that allow it to cause acute and chronic infections. Treatment of P. aeruginosa infections often fail due to its antibiotic resistance mechanisms, thus novel strategies aim at targeting virulence factors instead of growth-related features. However, there is currently not a clear understanding of the dynamic nature inherent to the wiring of its virulence networks.ResultsIn this study, we manually reconstructed the signalling and transcriptional regulatory networks of 12 acute (incl. pyocin and elastase) and 8 chronic virulence factors (incl. biofilm), and the 4 quorum sensing (QS) systems of P. aeruginosa. Using Boolean modelling (BM), we unveiled the important roles that stochasticity and node connectivity play in the networks’ inherent dynamicity and robustness. We showed that both the static interactions, as well as the time when the interactions take place, are important features in the QS network. In addition, we found that the virulence factors of the acute networks are under strict repression, or under an activation that is non-strict or oscillatory, while the chronic networks favour the repression of the virulence factor, with only moderate activation under certain conditions.ConclusionIn conclusion, our in silico-modelling framework provided us with a system-level view of the P. aeruginosa virulence and QS networks to gain new insights into the various mechanisms that support its pathogenicity and response to stressors targeting these networks. Thus, we suggest that BM provides an invaluable tool to guide the design of new treatments against P. aeruginosa.

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