scholarly journals Induction by Cationic Antimicrobial Peptides and Involvement in Intrinsic Polymyxin and Antimicrobial Peptide Resistance, Biofilm Formation, and Swarming Motility of PsrA in Pseudomonas aeruginosa

2008 ◽  
Vol 190 (16) ◽  
pp. 5624-5634 ◽  
Author(s):  
W. James Gooderham ◽  
Manjeet Bains ◽  
Joseph B. McPhee ◽  
Irith Wiegand ◽  
Robert E. W. Hancock
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Antimicrobial Peptides ◽  
Antimicrobial Peptide ◽  
Outer Membrane ◽  
Biofilm Formation ◽  
Metabolic Energy ◽  
Wild Type ◽  
Swarming Motility ◽  
Cationic Antimicrobial Peptides ◽  
Antimicrobial Peptide Resistance

ABSTRACT Pseudomonas aeruginosa is an important opportunistic pathogen that causes infections that can be extremely difficult to treat due to its high intrinsic antibiotic resistance and broad repertoire of virulence factors, both of which are highly regulated. It is demonstrated here that the psrA gene, encoding a transcriptional regulator, was upregulated in response to subinhibitory concentrations of cationic antimicrobial peptides. Compared to the wild type and the complemented mutant, a P. aeruginosa PAO1 psrA::Tn5 mutant displayed intrinsic supersusceptibility to polymyxin B, a last-resort antimicrobial used against multidrug-resistant infections, and the bovine neutrophil antimicrobial peptide indolicidin; this supersusceptibility phenotype correlated with increased outer membrane permeabilization by these agents. The psrA mutant was also defective in simple biofilm formation, rapid attachment, and swarming motility, all of which could be complemented by the cloned psrA gene. The role of PsrA in global gene regulation was studied by comparing the psrA mutant to the wild type by microarray analysis, demonstrating that 178 genes were up- or downregulated ≥2-fold (P ≤ 0.05). Dysregulated genes included those encoding certain known PsrA targets, those encoding the type III secretion apparatus and effectors, adhesion and motility genes, and a variety of metabolic, energy metabolism, and outer membrane permeability genes. This suggests that PsrA might be a key regulator of antimicrobial peptide resistance and virulence.

scholarly journals Effect of Nitroxides on Swarming Motility and Biofilm Formation, Multicellular Behaviors in Pseudomonas aeruginosa

2013 ◽  
Vol 57 (10) ◽  
pp. 4877-4881 ◽  
Author(s):  
César de la Fuente-Núñez ◽  
Fany Reffuveille ◽  
Kathryn E. Fairfull-Smith ◽  
Robert E. W. Hancock
Keyword(s):  
Nitric Oxide ◽  
Pseudomonas Aeruginosa ◽  
Biofilm Formation ◽  
Wild Type ◽  
Planktonic Cells ◽  
Swarming Motility ◽  
Content Type ◽  
Exogenous Addition ◽  
Biofilm Dispersion ◽  
Dispersal Activity

ABSTRACTThe ability of nitric oxide (NO) to induce biofilm dispersion has been well established. Here, we investigated the effect of nitroxides (sterically hindered nitric oxide analogues) on biofilm formation and swarming motility inPseudomonas aeruginosa. A transposon mutant unable to produce nitric oxide endogenously (nirS) was deficient in swarming motility relative to the wild type and the complemented strain. Moreover, expression of thenirSgene was upregulated by 9.65-fold in wild-type swarming cells compared to planktonic cells. Wild-type swarming levels were substantially restored upon the exogenous addition of nitroxide containing compounds, a finding consistent with the hypothesis that NO is necessary for swarming motility. Here, we showed that nitroxides not only mimicked the dispersal activity of NO but also prevented biofilms from forming in flow cell chambers. In addition, anirStransposon mutant was deficient in biofilm formation relative to the wild type and the complemented strain, thus implicating NO in the formation of biofilms. Intriguingly, despite its stand-alone action in inhibiting biofilm formation and promoting dispersal, a nitroxide partially restored the ability of anirSmutant to form biofilms.

scholarly journals Inverse Regulation of Biofilm Formation and Swarming Motility by Pseudomonas aeruginosa PA14

2007 ◽  
Vol 189 (9) ◽  
pp. 3603-3612 ◽  
Author(s):  
Nicky C. Caiazza ◽  
Judith H. Merritt ◽  
Kimberly M. Brothers ◽  
George A. O'Toole
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Biofilm Formation ◽  
Type Strain ◽  
Wild Type Strain ◽  
Opportunistic Pathogen ◽  
Wild Type ◽  
Regulatory Pathway ◽  
Early Step ◽  
Swarming Motility ◽  
Epistasis Analysis

ABSTRACT We previously reported that SadB, a protein of unknown function, is required for an early step in biofilm formation by the opportunistic pathogen Pseudomonas aeruginosa. Here we report that a mutation in sadB also results in increased swarming compared to the wild-type strain. Our data are consistent with a model in which SadB inversely regulates biofilm formation and swarming motility via its ability both to modulate flagellar reversals in a viscosity-dependent fashion and to influence the production of the Pel exopolysaccharide. We also show that SadB is required to properly modulate flagellar reversal rates via chemotaxis cluster IV (CheIV cluster). Mutational analyses of two components of the CheIV cluster, the methyl-accepting chemotaxis protein PilJ and the PilJ demethylase ChpB, support a model wherein this chemotaxis cluster participates in the inverse regulation of biofilm formation and swarming motility. Epistasis analysis indicates that SadB functions upstream of the CheIV cluster. We propose that P. aeruginosa utilizes a SadB-dependent, chemotaxis-like regulatory pathway to inversely regulate two key surface behaviors, biofilm formation and swarming motility.

scholarly journals Genome-Wide Analysis Reveals a RhlA-Dependent Modulation of Flagellar Genes in Pseudomonas Aeruginosa PAO1

2021 ◽  
Author(s):  
Michele Castro ◽  
Graciela Maria Dias ◽  
Tiago Salles ◽  
Núbia Cabral ◽  
Danielly Mariano ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Mutant Strain ◽  
Biofilm Formation ◽  
Dna Microarrays ◽  
Model Organism ◽  
Opportunistic Pathogen ◽  
Wild Type ◽  
Swarming Motility ◽  
Or Gene ◽  
Flagellar Genes

Abstract Background: Pseudomonas aeruginosa is an opportunistic pathogen and an important model organism for the study of bacterial group behaviors, including cell motility and biofilm formation. Rhamnolipids play a pivotal role on biofilm formation and motility phenotypes in P. aeruginosa, possibly acting as wetting agents and mediating chemotactic stimuli. However, no biochemical mechanism or gene regulatory network has been investigated in regard to rhamnolipids’ modulation of those group behaviors. Results: Using DNA microarrays, we investigated the transcriptomic profiles in the stationary phase of growth of wild-type P. aeruginosa PAO1 and a rhlA-mutant strain, unable to produce rhamnolipids. A total of 134 genes were differentially expressed, comprising different functional categories, indicating a significant physiological difference between the rhamnolipid-producing and non-producing strains. Interestingly, several flagellar genes are repressed in the mutant strain, which directly relates to the non-motile phenotype of the rhlA-minus strain. Swarming motility was restored with the addition of exogenous rhamnolipids obtained from the wild-type strain. Conclusions: Our results show significant evidence that rhamnolipids and/or their precursors, 3-(3-hydroxyalkanoyloxy) alkanoic acids, the major biosynthetic products of rhlABC pathway, seem to modulate gene expression in P. aeruginosa. Swarming motility assays support this hypothesis, since the non-motile rhlA-mutant strain had its swarming ability restored by the addition of exogenous rhamnolipids.

scholarly journals Deletion ofmtrCin Haemophilus ducreyi Increases Sensitivity to Human Antimicrobial Peptides and Activates the CpxRA Regulon

2011 ◽  
Vol 79 (6) ◽  
pp. 2324-2334 ◽  
Author(s):  
Sherri D. Rinker ◽  
Michael P. Trombley ◽  
Xiaoping Gu ◽  
Kate R. Fortney ◽  
Margaret E. Bauer
Keyword(s):  
Antimicrobial Peptides ◽  
Antimicrobial Peptide ◽  
Resistance Mechanism ◽  
Proton Motive Force ◽  
Human Infection ◽  
Motive Force ◽  
Haemophilus Ducreyi ◽  
Wild Type ◽  
Content Type ◽  
Antimicrobial Peptide Resistance

ABSTRACTHaemophilus ducreyiresists killing by antimicrobial peptides encountered during human infection, including cathelicidin LL-37, α-defensins, and β-defensins. In this study, we examined the role of the proton motive force-dependent multiple transferable resistance (MTR) transporter in antimicrobial peptide resistance inH. ducreyi. We found a proton motive force-dependent effect onH. ducreyi's resistance to LL-37 and β-defensin HBD-3, but not α-defensin HNP-2. Deletion of the membrane fusion protein MtrC renderedH. ducreyimore sensitive to LL-37 and human β-defensins but had relatively little effect on α-defensin resistance. ThemtrCmutant 35000HPmtrCexhibited phenotypic changes in outer membrane protein profiles, colony morphology, and serum sensitivity, which were restored to wild type bytrans-complementation withmtrC. Similar phenotypes were reported in acpxAmutant; activation of the two-component CpxRA regulator was confirmed by showing transcriptional effects on CpxRA-regulated genes in 35000HPmtrC. AcpxRmutant had wild-type levels of antimicrobial peptide resistance; acpxAmutation had little effect on defensin resistance but led to increased sensitivity to LL-37. 35000HPmtrCwas more sensitive than thecpxAmutant to LL-37, indicating that MTR contributed to LL-37 resistance independent of the CpxRA regulon. The CpxRA regulon did not affect proton motive force-dependent antimicrobial peptide resistance; however, 35000HPmtrChad lost proton motive force-dependent peptide resistance, suggesting that the MTR transporter promotes proton motive force-dependent resistance to LL-37 and human β-defensins. This is the first report of a β-defensin resistance mechanism inH. ducreyiand shows that LL-37 resistance inH. ducreyiis multifactorial.

scholarly journals The PA3177 Gene Encodes an Active Diguanylate Cyclase That Contributes to Biofilm Antimicrobial Tolerance but Not Biofilm Formation by Pseudomonas aeruginosa

2018 ◽  
Vol 62 (10) ◽  
Author(s):  
Bandita Poudyal ◽  
Karin Sauer
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Biofilm Formation ◽  
Antimicrobial Agents ◽  
Drug Tolerance ◽  
Diguanylate Cyclase ◽  
Wild Type ◽  
Planktonic Cells ◽  
Swarming Motility ◽  
Content Type ◽  
First Time

ABSTRACT A hallmark of biofilms is their heightened resistance to antimicrobial agents. Recent findings suggested a role for bis-(3′-5′)-cyclic dimeric GMP (c-di-GMP) in the susceptibility of bacteria to antimicrobial agents; however, no c-di-GMP modulating enzyme(s) contributing to the drug tolerance phenotype of biofilms has been identified. The goal of this study was to determine whether c-di-GMP modulating enzyme(s) specifically contributes to the biofilm drug tolerance of Pseudomonas aeruginosa. Using transcriptome sequencing combined with biofilm susceptibility assays, we identified PA3177 encoding a probable diguanylate cyclase. PA3177 was confirmed to be an active diguanylate cyclase, with overexpression affecting swimming and swarming motility, and inactivation affecting cellular c-di-GMP levels of biofilm but not planktonic cells. Inactivation of PA3177 rendered P. aeruginosa PAO1 biofilms susceptible to tobramycin and hydrogen peroxide. Inactivation of PA3177 also eliminated the recalcitrance of biofilms to killing by tobramycin, with multicopy expression of PA3177 but not PA3177_GGAAF harboring substitutions in the active site, restoring tolerance to wild-type levels. Susceptibility was linked to BrlR, a previously described transcriptional regulator contributing to biofilm tolerance, with inactivation of PA3177 negatively impacting BrlR levels and BrlR-DNA binding. While PA3177 contributed to biofilm drug tolerance, inactivation of PA3177 had no effect on attachment and biofilm formation. Our findings demonstrate for the first time that biofilm drug tolerance by P. aeruginosa is linked to a specific c-di-GMP modulating enzyme, PA3177, with the pool of PA3177-generated c-di-GMP only contributing to biofilm drug tolerance but not to biofilm formation.

scholarly journals Sensor Kinase PA4398 Modulates Swarming Motility and Biofilm Formation in Pseudomonas aeruginosa PA14

2014 ◽  
Vol 81 (4) ◽  
pp. 1274-1285 ◽  
Author(s):  
Janine Strehmel ◽  
Anke Neidig ◽  
Michael Nusser ◽  
Robert Geffers ◽  
Gerald Brenner-Weiss ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Biofilm Formation ◽  
Sensor Kinase ◽  
Wild Type ◽  
Swarming Motility ◽  
Content Type ◽  
Regulatory Systems ◽  
Opportunistic Human Pathogen ◽  
Swarming Behavior

ABSTRACTPseudomonas aeruginosais an opportunistic human pathogen that is able to sense and adapt to numerous environmental stimuli by the use of transcriptional regulators, including two-component regulatory systems. In this study, we demonstrate that the sensor kinase PA4398 is involved in the regulation of swarming motility and biofilm formation inP. aeruginosaPA14. A PA4398−mutant strain was considerably impaired in swarming motility, while biofilm formation was increased by approximately 2-fold. The PA4398−mutant showed no changes in growth rate, rhamnolipid synthesis, or the production of the Pel exopolysaccharide but exhibited levels of the intracellular second messenger cyclic dimeric GMP (c-di-GMP) 50% higher than those in wild-type cells. The role of PA4398 in gene regulation was investigated by comparing the PA4398−mutant to the wild-type strain by using microarray analysis, which demonstrated that 64 genes were up- or downregulated more than 1.5-fold (P< 0.05) under swarming conditions. In addition, more-sensitive real-time PCR studies were performed on genes known to be involved in c-di-GMP metabolism. Among the dysregulated genes were several involved in the synthesis and degradation of c-di-GMP or in the biosynthesis, transport, or function of the iron-scavenging siderophores pyoverdine and pyochelin, in agreement with the swarming phenotype observed. By analyzing additional mutants of selected pyoverdine- and pyochelin-related genes, we were able to show that not onlypvdQbut alsopvdR,fptA,pchA,pchD, andpchHare essential for the normal swarming behavior ofP. aeruginosaPA14 and may also contribute to the swarming-deficient phenotype of the PA4398−mutant in addition to elevated c-di-GMP levels.

scholarly journals Biofilm formation by Pseudomonas aeruginosa wild type, flagella and type IV pili mutants

2003 ◽  
Vol 48 (6) ◽  
pp. 1511-1524 ◽  
Author(s):  
Mikkel Klausen ◽  
Arne Heydorn ◽  
Paula Ragas ◽  
Lotte Lambertsen ◽  
Anders Aaes-Jørgensen ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Biofilm Formation ◽  
Type Iv Pili ◽  
Wild Type ◽  
Type Iv

scholarly journals Bordetella pertussis Lipid A Glucosamine Modification Confers Resistance to Cationic Antimicrobial Peptides and Increases Resistance to Outer Membrane Perturbation

2014 ◽  
Vol 58 (8) ◽  
pp. 4931-4934 ◽  
Author(s):  
Nita R. Shah ◽  
Robert E. W. Hancock ◽  
Rachel C. Fernandez
Keyword(s):  
Immune System ◽  
Antimicrobial Peptides ◽  
Outer Membrane ◽  
Bordetella Pertussis ◽  
Lipid A ◽  
Whooping Cough ◽  
Human Immune System ◽  
Cationic Antimicrobial Peptides ◽  
Content Type ◽  
Membrane Perturbation

ABSTRACTBordetella pertussis, the causative agent of whooping cough, has many strategies for evading the human immune system. Lipopolysaccharide (LPS) is an important Gram-negative bacterial surface structure that activates the immune system via Toll-like receptor 4 and enables susceptibility to cationic antimicrobial peptides (CAMPs). We show modification of the lipid A region of LPS with glucosamine increased resistance to numerous CAMPs, including LL-37. Furthermore, we demonstrate that this glucosamine modification increased resistance to outer membrane perturbation.

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