scholarly journals Evolution of the quorum sensing regulon in cooperating populations of Pseudomonas aeruginosa

2021 ◽  
Author(s):  
Nicole E Smalley ◽  
Amy L Schaefer ◽  
Kyle L Asfahl ◽  
Crystal Perez ◽  
E Peter Greenberg ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Cell Communication ◽  
Opportunistic Pathogen ◽  
Quorum Quenching ◽  
Homoserine Lactone ◽  
Rna Seq ◽  
Bacterial Strains ◽  
Communication And Coordination

The bacterium Pseudomonas aeruginosa is an opportunistic pathogen and it thrives in many different saprophytic habitats. In this bacterium acyl-homoserine lactone quorum sensing (QS) can activate expression of over 100 genes, many of which code for extracellular products. P. aeruginosa has become a model for studies of cell-cell communication and coordination of cooperative activities. We hypothesized that long-term growth of bacteria under conditions where only limited QS-controlled functions were required would result in a reduction in the size of the QS-controlled regulon. To test this hypothesis, we grew P. aeruginosa for about 1000 generations in a condition in which expression of QS-activated genes is required for growth. We compared the QS regulons of populations after about 35 generations to those after about 1000 generations in two independent lineages by using quorum quenching and RNA-seq technology. In one evolved lineage the number of QS-activated genes identified was reduced by about 70% and in the other by about 45%. Our results lend important insights about the variations in the number of QS-activated genes reported for different bacterial strains and, more broadly, about the environmental histories of P. aeruginosa.

scholarly journals THE STUDY OF THE ANTAGONISTIC ACTIVITY OF BACTERIA SUPPRESSING THE SYNTHESIS OF PHENAZINES PSEUDOMONAS AERUGINOSA

2019 ◽  
Vol 48 (5) ◽  
pp. 23-29
Author(s):  
A. S. Donchenko ◽  
V. V. Fomenko ◽  
V. G. Vasiliev ◽  
V. N. Afonyushkin ◽  
N. A. Donchenko ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Hydrochloric Acid ◽  
Quorum Sensing ◽  
Quorum Quenching ◽  
Homoserine Lactone ◽  
Antagonistic Activity ◽  
Bacterial Strains ◽  
Bacterial Cultures ◽  
Random Nature ◽  
Lactobacillus Spp

The purpose of the study was the search for microorganisms capable of suppressing quorum feelings associated with the production of phenazines (pyocyanin). The formation of pyocyanine, related to oxyphenazines, is one of the indicators of the quorum-sensing reaction. In order to search for antagonistically active bacterial strains, the microorganisms were co-cullured with the cultures of Pseudomonas aeruginosa wherein the suppression of oxyphenazine production was determined. We used 14 cultures of bacteria from the genera Pseudomonas, Acinetobacter, Enterobacter, Staphylococcus, Microbacterium, Serratia, Sphingobacterium, Lactobacillus, Weisella to find strains suppressing the production of pyocyanin. Piocanin was successively extracted with chloroform and 0.2 M hydrochloric acid, after which its content was determined spectrophotometrically at a wavelength of 520 nm. Several bacterial cultures characterized by the ability to inhibit the production of oxyphenazine in co-cultivation tests with Pseudomonas aeruginosa were found. The identified microorganisms belonged to the microorganisms of the genera Acinetobacter and Pseudomonas, Lactobacillus and Weisella. The Kruskal-Wallis criterion - H (5, N = 21) = 11.86902 is statistically significant (p = 0.0366). The distribution of cultures in the inhibition of the production of oxyphenazines in the experiments on co-cultivation with Pseudomonas aeruginosa was not binomial, which implies the non-random nature of the distribution of cultures according to the results of co-cultivation. Thus, the levels of inhibition of the production of phenazines for different taxa of bacteria in the co-cultivation tests were statistically significantly different from each other. The largest sum of ranks belongs to the group Lactobacillus spp. and this taxon has the greatest effect on the content of phenazines. The decrease in the concentration of fhe final product (pyocyanin), the synthesis of which is initiated by butanol-homoserine lactone, can be associated with the mechanisms of quorum-quenching, and the mechanisms of antagonistic activity of microorganisms that affect the production of the aforementioned metabolites of P. aeruginosa.

scholarly journals GidA Posttranscriptionally Regulates rhl Quorum Sensing in Pseudomonas aeruginosa

2009 ◽  
Vol 191 (18) ◽  
pp. 5785-5792 ◽  
Author(s):  
Rashmi Gupta ◽  
Timothy R. Gobble ◽  
Martin Schuster
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Flavin Adenine Dinucleotide ◽  
Skim Milk ◽  
Opportunistic Pathogen ◽  
Homoserine Lactone ◽  
Trna Modification ◽  
Loss Of Function ◽  
Novel Genes ◽  
Lasa Protease

ABSTRACT The opportunistic pathogen Pseudomonas aeruginosa utilizes two interconnected acyl-homoserine lactone quorum-sensing (acyl-HSL QS) systems, LasRI and RhlRI, to regulate the expression of hundreds of genes. The QS circuitry itself is integrated into a complex network of regulation by other factors. However, our understanding of this network is still unlikely to be complete, as a comprehensive, saturating approach to identifying regulatory components has never been attempted. Here, we utilized a nonredundant P. aeruginosa PA14 transposon library to identify additional genes that regulate QS at the level of LasRI/RhlRI. We initially screened all 5,459 mutants for loss of function in one QS-controlled trait (skim milk proteolysis) and then rescreened attenuated candidates for defects in other QS phenotypes (LasA protease, rhamnolipid, and pyocyanin production) to exclude mutants defective in functions other than QS. We identified several known and novel genes, but only two novel genes, gidA and pcnB, affected all of the traits assayed. We characterized gidA, which exhibited the most striking QS phenotypes, further. This gene is predicted to encode a conserved flavin adenine dinucleotide-binding protein involved in tRNA modification. Inactivation of the gene primarily affected rhlR-dependent QS phenotypes such as LasA, pyocyanin, and rhamnolipid production. GidA affected RhlR protein but not transcript levels and also had no impact on LasR and acyl-HSL production. Overexpression of rhlR in a gidA mutant partially restored QS-dependent phenotypes. Taken together, these results indicate that GidA selectively controls QS gene expression posttranscriptionally via RhlR-dependent and -independent pathways.

scholarly journals Microarray Analysis of Pseudomonas aeruginosa Quorum-Sensing Regulons: Effects of Growth Phase and Environment

2003 ◽  
Vol 185 (7) ◽  
pp. 2080-2095 ◽  
Author(s):  
Victoria E. Wagner ◽  
Daniel Bushnell ◽  
Luciano Passador ◽  
Andrew I. Brooks ◽  
Barbara H. Iglewski
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Expression Patterns ◽  
Antibiotic Sensitivity ◽  
Opportunistic Pathogen ◽  
Homoserine Lactone ◽  
Medium Composition ◽  
Logarithmic Phase ◽  
Significant Differential Expression ◽  
Biofilm Development

ABSTRACT Bacterial communication via quorum sensing (QS) has been reported to be important in the production of virulence factors, antibiotic sensitivity, and biofilm development. Two QS systems, known as the las and rhl systems, have been identified previously in the opportunistic pathogen Pseudomonas aeruginosa. High-density oligonucleotide microarrays for the P. aeruginosa PAO1 genome were used to investigate global gene expression patterns modulated by QS regulons. In the initial experiments we focused on identifying las and/or rhl QS-regulated genes using a QS signal generation-deficient mutant (PAO-JP2) that was cultured with and without added exogenous autoinducers [N-(3-oxododecanoyl) homoserine lactone and N-butyryl homoserine lactone]. Conservatively, 616 genes showed statistically significant differential expression (P ≤ 0.05) in response to the exogenous autoinducers and were classified as QS regulated. A total of 244 genes were identified as being QS regulated at the mid-logarithmic phase, and 450 genes were identified as being QS regulated at the early stationary phase. Most of the previously reported QS-promoted genes were confirmed, and a large number of additional QS-promoted genes were identified. Importantly, 222 genes were identified as being QS repressed. Environmental factors, such as medium composition and oxygen availability, eliminated detection of transcripts of many genes that were identified as being QS regulated.

scholarly journals The flavanone naringenin reduces the production of quorum sensing-controlled virulence factors in Pseudomonas aeruginosa PAO1

Microbiology ◽  
2011 ◽  
Vol 157 (7) ◽  
pp. 2120-2132 ◽  
Author(s):  
Olivier M. Vandeputte ◽  
Martin Kiendrebeogo ◽  
Tsiry Rasamiravaka ◽  
Caroline Stévigny ◽  
Pierre Duez ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Virulence Factors ◽  
Pathogenic Bacteria ◽  
Opportunistic Pathogen ◽  
Homoserine Lactone ◽  
Gene Products ◽  
Strain Pao1 ◽  
Preliminary Screening ◽  
Mutant Strains

Preliminary screening of the Malagasy plant Combretum albiflorum for compounds attenuating the production of quorum sensing (QS)-controlled virulence factors in bacteria led to the identification of active fractions containing flavonoids. In the present study, several flavonoids belonging to the flavone, flavanone, flavonol and chalcone structural groups were screened for their capacity to reduce the production of QS-controlled factors in the opportunistic pathogen Pseudomonas aeruginosa (strain PAO1). Flavanones (i.e. naringenin, eriodictyol and taxifolin) significantly reduced the production of pyocyanin and elastase in P. aeruginosa without affecting bacterial growth. Consistently, naringenin and taxifolin reduced the expression of several QS-controlled genes (i.e. lasI, lasR, rhlI, rhlR, lasA, lasB, phzA1 and rhlA) in P. aeruginosa PAO1. Naringenin also dramatically reduced the production of the acylhomoserine lactones N-(3-oxododecanoyl)-l-homoserine lactone (3-oxo-C12-HSL) and N-butanoyl-l-homoserine lactone (C4-HSL), which is driven by the lasI and rhlI gene products, respectively. In addition, using mutant strains deficient for autoinduction (ΔlasI and ΔrhlI) and LasR- and RhlR-based biosensors, it was shown that QS inhibition by naringenin not only is the consequence of a reduced production of autoinduction compounds but also results from a defect in the proper functioning of the RlhR–C4-HSL complex. Widely distributed in the plant kingdom, flavonoids are known for their numerous and determinant roles in plant physiology, plant development and in the success of plant–rhizobia interactions, but, as shown here, some of them also have a role as inhibitors of the virulence of pathogenic bacteria by interfering with QS mechanisms.

scholarly journals The Quorum-Sensing Negative Regulator RsaL of Pseudomonas aeruginosa Binds to the lasI Promoter

2006 ◽  
Vol 188 (2) ◽  
pp. 815-819 ◽  
Author(s):  
Giordano Rampioni ◽  
Iris Bertani ◽  
Elisabetta Zennaro ◽  
Fabio Polticelli ◽  
Vittorio Venturi ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Binding Site ◽  
Opportunistic Pathogen ◽  
Bidirectional Promoter ◽  
Homoserine Lactone ◽  
Negative Regulator ◽  
Direct Demonstration ◽  
Dna Binding Site

ABSTRACT A mutation in the rsaL gene of Pseudomonas aeruginosa produces dramatically higher amounts of N-acyl homoserine lactone with respect to the wild type, highlighting the key role of this negative regulator in controlling quorum sensing (QS) in this opportunistic pathogen. The DNA binding site of the RsaL protein on the rsaL-lasI bidirectional promoter partially overlaps the binding site of the LasR protein, consistent with the hypothesis that RsaL and LasR could be in binding competition on this promoter. This is the first direct demonstration that RsaL acts as a QS negative regulator by binding to the lasI promoter.

scholarly journals ThePseudomonas aeruginosaOrphan Quorum Sensing Signal Receptor QscR Regulates Global Quorum Sensing Gene Expression by Activating a Single Linked Operon

mBio ◽  
2018 ◽  
Vol 9 (4) ◽  
Author(s):  
Fengming Ding ◽  
Ken-Ichi Oinuma ◽  
Nicole E. Smalley ◽  
Amy L. Schaefer ◽  
Omar Hamwy ◽  
...  
Keyword(s):  
Gene Expression ◽  
Pseudomonas Aeruginosa ◽  
Transcription Factor ◽  
Quorum Sensing ◽  
Cell Communication ◽  
Homoserine Lactone ◽  
Acyl Homoserine Lactone ◽  
Null Mutant ◽  
Content Type ◽  
Single Operon

ABSTRACTPseudomonas aeruginosauses two acyl-homoserine lactone signals and two quorum sensing (QS) transcription factors, LasR and RhlR, to activate dozens of genes. LasR responds toN-3-oxo-dodecanoyl-homoserine lactone (3OC12-HSL) and RhlR toN-butanoyl-homoserine lactone (C4-HSL). There is a thirdP. aeruginosaacyl-homoserine-lactone-responsive transcription factor, QscR, which acts to dampen or delay activation of genes by LasR and RhlR by an unknown mechanism. To better understand the role of QscR inP. aeruginosaQS, we performed a chromatin immunoprecipitation analysis, which showed this transcription factor bound the promoter of only a single operon of three genes linked toqscR, PA1895 to PA1897. Other genes that appear to be regulated by QscR in transcriptome studies were not direct targets of QscR. Deletion of PA1897 recapitulates the early QS activation phenotype of a QscR-null mutant, and the phenotype of a QscR-null mutant was complemented by PA1895-1897 but not by PA1897 alone. We conclude that QscR acts to modulate quorum sensing through regulation of a single operon, apparently raising the QS threshold of the population and providing a “brake” on QS autoinduction.IMPORTANCEQuorum sensing, a cell-cell communication system, is broadly distributed among bacteria and is commonly used to regulate the production of shared products. An important consequence of quorum sensing is a delay in production of certain products until the population density is high. The bacteriumPseudomonas aeruginosahas a particularly complicated quorum sensing system involving multiple signals and receptors. One of these receptors, QscR, downregulates gene expression, unlike the other receptors inP. aeruginosa. QscR does so by inducing the expression of a single operon whose function provides an element of resistance to a population reaching a quorum. This finding has importance for design of quorum sensing inhibitory strategies and can also inform design of synthetic biological circuits that use quorum sensing receptors to regulate gene expression.

scholarly journals A Distinct QscR Regulon in the Pseudomonas aeruginosa Quorum-Sensing Circuit

2006 ◽  
Vol 188 (9) ◽  
pp. 3365-3370 ◽  
Author(s):  
Yannick Lequette ◽  
Joon-Hee Lee ◽  
Fouzia Ledgham ◽  
Andrée Lazdunski ◽  
E. Peter Greenberg
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Opportunistic Pathogen ◽  
Homoserine Lactone ◽  
Acyl Homoserine Lactone ◽  
Signal Molecule ◽  
Control Of Gene Expression ◽  
Signaling Systems ◽  
Sensing Systems

ABSTRACT The opportunistic pathogen Pseudomonas aeruginosa possesses two complete acyl-homoserine lactone (acyl-HSL) signaling systems. One system consists of LasI and LasR, which generate a 3-oxododecanoyl-homoserine lactone signal and respond to that signal, respectively. The other system is RhlI and RhlR, which generate butanoyl-homoserine lactone and respond to butanoyl-homoserine lactone, respectively. These quorum-sensing systems control hundreds of genes. There is also an orphan LasR-RhlR homolog, QscR, for which there is no cognate acyl-HSL synthetic enzyme. We previously reported that a qscR mutant is hypervirulent and showed that QscR transiently represses a few quorum-sensing-controlled genes. To better understand the role of QscR in P. aeruginosa gene regulation and to better understand the relationship between QscR, LasR, and RhlR control of gene expression, we used transcription profiling to identify a QscR-dependent regulon. Our analysis revealed that QscR activates some genes and represses others. Some of the repressed genes are not regulated by the LasR-I or RhlR-I systems, while others are. The LasI-generated 3-oxododecanoyl-homoserine lactone serves as a signal molecule for QscR. Thus, QscR appears to be an integral component of the P. aeruginosa quorum-sensing circuitry. QscR uses the LasI-generated acyl-homoserine lactone signal and controls a specific regulon that overlaps with the already overlapping LasR- and RhlR-dependent regulons.

scholarly journals Instantaneous Within-Patient Diversity of Pseudomonas aeruginosa Quorum-Sensing Populations from Cystic Fibrosis Lung Infections

2009 ◽  
Vol 77 (12) ◽  
pp. 5631-5639 ◽  
Author(s):  
Cara N. Wilder ◽  
Gopal Allada ◽  
Martin Schuster
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Opportunistic Pathogen ◽  
Homoserine Lactone ◽  
Loss Of Function ◽  
Selective Forces ◽  
Lung Infections

ABSTRACT In the opportunistic pathogen Pseudomonas aeruginosa, acyl-homoserine lactone (acyl-HSL) quorum sensing (QS) regulates biofilm formation and expression of many extracellular virulence factors. Curiously, QS-deficient variants, often carrying mutations in the central QS regulator LasR, are frequently isolated from infections, particularly from cystic fibrosis (CF) lung infections. Very little is known about the proportion and diversity of these QS variants in individual infections. Such information is desirable to better understand the selective forces that drive the evolution of QS phenotypes, including social cheating and innate (nonsocial) benefits. To obtain insight into the instantaneous within-patient diversity of QS, we assayed a panel of 135 concurrent P. aeruginosa isolates from eight different adult CF patients (9 to 20 isolates per patient) for various QS-controlled phenotypes. Most patients contained complex mixtures of QS-proficient and -deficient isolates. Among all patients, deficiency in individual phenotypes ranged from 0 to about 90%. Acyl-HSL, sequencing, and complementation analyses of variants with global loss-of-function phenotypes revealed dependency upon the central QS circuitry genes lasR, lasI, and rhlI. Deficient and proficient isolates were clonally related, implying evolution from a common ancestor in vivo. Our results show that the diversity of QS types is high within and among patients, suggesting diverse selection pressures in the CF lung. A single selective mechanism, be it of a social or nonsocial nature, is unlikely to account for such heterogeneity. The observed diversity also shows that conclusions about the properties of P. aeruginosa QS populations in individual CF infections cannot be drawn from the characterization of one or a few selected isolates.

scholarly journals Pseudomonas aeruginosa Increases Formation of Multidrug-Tolerant Persister Cells in Response to Quorum-Sensing Signaling Molecules

2010 ◽  
Vol 192 (7) ◽  
pp. 1946-1955 ◽  
Author(s):  
Nina Möker ◽  
Charles R. Dean ◽  
Jianshi Tao
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Bacterial Species ◽  
Opportunistic Pathogen ◽  
Homoserine Lactone ◽  
Signaling Molecules ◽  
Persister Cells ◽  
E Coli ◽  
Underlying Mechanisms ◽  
Lethal Doses

ABSTRACT Bacterial persister cells constitute a small portion of a culture which is tolerant to killing by lethal doses of bactericidal antibiotics. These phenotypic variants are formed in numerous bacterial species, including those with clinical relevance like the opportunistic pathogen Pseudomonas aeruginosa. Although persisters are believed to contribute to difficulties in the treatment of many infectious diseases, the underlying mechanisms affecting persister formation are not well understood. Here we show that even though P. aeruginosa cultures have a significantly smaller fraction of multidrug-tolerant persister cells than cultures of Escherichia coli or Staphylococcus aureus, they can increase persister numbers in response to quorum-sensing-related signaling molecules. The phenazine pyocyanin (and the closely related molecule paraquat) and the acyl-homoserine lactone 3-OC12-HSL significantly increased the persister numbers in logarithmic P. aeruginosa PAO1 or PA14 cultures but not in E. coli or S. aureus cultures.

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