scholarly journals PA0335, a Gene Encoding Histidinol Phosphate Phosphatase, Mediates Histidine Auxotrophy in Pseudomonas aeruginosa

2019 ◽  
Vol 86 (5) ◽  
Author(s):  
Yulu Wang ◽  
Liyue Wang ◽  
Jian Zhang ◽  
Xintong Duan ◽  
Yuqi Feng ◽  
...  

ABSTRACT The biosynthesis of histidine, a proteinogenic amino acid, has been extensively studied due to its importance in bacterial growth and survival. Histidinol-phosphate phosphatase (Hol-Pase), which is responsible for the penultimate step of histidine biosynthesis, is generally the last enzyme to be characterized in many bacteria because its origin and evolution are more complex compared to other enzymes in histidine biosynthesis. However, none of the enzymes in histidine biosynthesis, including Hol-Pase, have been characterized in Pseudomonas aeruginosa, which is an important opportunistic Gram-negative pathogen that can cause serious human infections. In our previous work, a transposon mutant of P. aeruginosa was found to display a growth defect on glucose-containing minimal solid medium. In this study, we found that the growth defect was due to incomplete histidine auxotrophy caused by PA0335 inactivation. Subsequently, PA0335 was shown to encode Hol-Pase, and its function and enzymatic activity were investigated using genetic and biochemical methods. In addition to PA0335, the roles of 12 other predicted genes involved in histidine biosynthesis in P. aeruginosa were examined. Among them, hisC2 (PA3165), hisH2 (PA3152), and hisF2 (PA3151) were found to be dispensable for histidine synthesis, whereas hisG (PA4449), hisE (PA5067), hisF1 (PA5140), hisB (PA5143), hisI (PA5066), hisC1 (PA4447), and hisA (PA5141) were essential because deletion of each resulted in complete histidine auxotrophy; similar to the case for PA0335, hisH1 (PA5142) or hisD (PA4448) deletion caused incomplete histidine auxotrophy. Taken together, our results outline the histidine synthesis pathway of P. aeruginosa. IMPORTANCE Histidine is a common amino acid in proteins. Because it plays critical roles in bacterial metabolism, its biosynthetic pathway in many bacteria has been elucidated. However, the pathway remains unclear in Pseudomonas aeruginosa, an important opportunistic pathogen in clinical settings; in particular, there is scant knowledge about histidinol-phosphate phosphatase (Hol-Pase), which has a complex origin and evolution. In this study, P. aeruginosa Hol-Pase was identified and characterized. Furthermore, the roles of all other predicted genes involved in histidine biosynthesis were examined. Our results illustrate the histidine synthesis pathway of P. aeruginosa. The knowledge obtained from this study may help in developing strategies to control P. aeruginosa-related infections. In addition, some enzymes of the histidine synthesis pathway from P. aeruginosa might be used as elements of histidine synthetic biology in other industrial microorganisms.

2019 ◽  
Vol 201 (20) ◽  
Author(s):  
Ian T. Hill ◽  
Thomas Tallo ◽  
Matthew J. Dorman ◽  
Simon L. Dove

ABSTRACT Hfq is an RNA chaperone that serves as a master regulator of bacterial physiology. Here we show that in the opportunistic pathogen Pseudomonas aeruginosa, the loss of Hfq can result in a dramatic reduction in growth in a manner that is dependent upon MexT, a transcription regulator that governs antibiotic resistance in this organism. Using a combination of chromatin immunoprecipitation with high-throughput sequencing and transposon insertion sequencing, we identify the MexT-activated genes responsible for mediating the growth defect of hfq mutant cells. These include a newly identified MexT-controlled gene that we call hilR. We demonstrate that hilR encodes a small protein that is acutely toxic to wild-type cells when produced ectopically. Furthermore, we show that hilR expression is negatively regulated by Hfq, offering a possible explanation for the growth defect of hfq mutant cells. Finally, we present evidence that the expression of MexT-activated genes is dependent upon GshA, an enzyme involved in the synthesis of glutathione. Our findings suggest that Hfq can influence the growth of P. aeruginosa by limiting the toxic effects of specific MexT-regulated genes. Moreover, our results identify glutathione to be a factor important for the in vivo activity of MexT. IMPORTANCE Here we show that the conserved RNA chaperone Hfq is important for the growth of the opportunistic pathogen Pseudomonas aeruginosa. We found that the growth defect of hfq mutant cells is dependent upon the expression of genes that are under the control of the transcription regulator MexT. These include a gene that we refer to as hilR, which we show is negatively regulated by Hfq and encodes a small protein that can be toxic when ectopically produced in wild-type cells. Thus, Hfq can influence the growth of P. aeruginosa by limiting the toxic effects of MexT-regulated genes, including one encoding a previously unrecognized small protein. We also show that MexT activity depends on an enzyme that synthesizes glutathione.


2020 ◽  
Vol 9 (26) ◽  
Author(s):  
Andrea Sass ◽  
Tom Coenye

ABSTRACT Pseudomonas aeruginosa is an opportunistic pathogen that is able to cause various infections, including airway infections in cystic fibrosis patients. Here, we present the complete closed and annotated genome sequence of P. aeruginosa AA2, an isolate obtained early during infection of the respiratory tract of a German cystic fibrosis patient.


mSphere ◽  
2020 ◽  
Vol 5 (4) ◽  
Author(s):  
Tianyuan Cao ◽  
Jonathan V. Sweedler ◽  
Paul W. Bohn ◽  
Joshua D. Shrout

ABSTRACT Pseudomonas aeruginosa is an opportunistic human pathogen important to diseases such as cystic fibrosis. P. aeruginosa has multiple quorum-sensing (QS) systems, one of which utilizes the signaling molecule 2-heptyl-3-hydroxy-4-quinolone (Pseudomonas quinolone signal [PQS]). Here, we use hyperspectral Raman imaging to elucidate the spatiotemporal PQS distributions that determine how P. aeruginosa regulates surface colonization and its response to both metabolic stress and competition from other bacterial strains. These chemical imaging experiments illustrate the strong link between environmental challenges, such as metabolic stress caused by nutritional limitations or the presence of another bacterial species, and PQS signaling. Metabolic stress elicits a complex response in which limited nutrients induce the bacteria to produce PQS earlier, but the bacteria may also pause PQS production entirely if the nutrient concentration is too low. Separately, coculturing P. aeruginosa in the proximity of another bacterial species, or its culture supernatant, results in earlier production of PQS. However, these differences in PQS appearance are not observed for all alkyl quinolones (AQs) measured; the spatiotemporal response of 2-heptyl-4-hydroxyquinoline N-oxide (HQNO) is highly uniform for most conditions. These insights on the spatiotemporal distributions of quinolones provide additional perspective on the behavior of P. aeruginosa in response to different environmental cues. IMPORTANCE Alkyl quinolones (AQs), including Pseudomonas quinolone signal (PQS), made by the opportunistic pathogen Pseudomonas aeruginosa have been associated with both population density and stress. The regulation of AQ production is known to be complex, and the stimuli that modulate AQ responses are not fully clear. Here, we have used hyperspectral Raman chemical imaging to examine the temporal and spatial profiles of AQs exhibited by P. aeruginosa under several potentially stressful conditions. We found that metabolic stress, effected by carbon limitation, or competition stress, effected by proximity to other species, resulted in accelerated PQS production. This competition effect did not require cell-to-cell interaction, as evidenced by the fact that the addition of supernatants from either Escherichia coli or Staphylococcus aureus led to early appearance of PQS. Lastly, the fact that these modulations were observed for PQS but not for all AQs suggests a high level of complexity in AQ regulation that remains to be discerned.


2020 ◽  
Vol 64 (6) ◽  
Author(s):  
Fabrice Compain ◽  
Agathe Debray ◽  
Pauline Adjadj ◽  
Delphine Dorchêne ◽  
Michel Arthur

ABSTRACT Chromosomal and plasmid-borne AmpC cephalosporinases are a major resistance mechanism to β-lactams in Enterobacteriaceae and Pseudomonas aeruginosa. The new β-lactamase inhibitor avibactam effectively inhibits class C enzymes and can fully restore ceftazidime susceptibility. The conserved amino acid residue Asn346 of AmpC cephalosporinases directly interacts with the avibactam sulfonate. Disruption of this interaction caused by the N346Y amino acid substitution in Citrobacter freundii AmpC was previously shown to confer resistance to the ceftazidime-avibactam combination (CAZ-AVI). The aim of this study was to phenotypically and biochemically characterize the consequences of the N346Y substitution in various AmpC backgrounds. Introduction of N346Y into Enterobacter cloacae AmpC (AmpCcloacae), plasmid-mediated DHA-1, and P. aeruginosa PDC-5 led to 270-, 12,000-, and 79-fold decreases in the inhibitory efficacy (k2/Ki) of avibactam, respectively. The kinetic parameters of AmpCcloacae and DHA-1 for ceftazidime hydrolysis were moderately affected by the substitution. Accordingly, AmpCcloacae and DHA-1 harboring N346Y conferred CAZ-AVI resistance (MIC of ceftazidime of 16 μg/ml in the presence of 4 μg/ml of avibactam). In contrast, production of PDC-5 N346Y was associated with a lower MIC (4 μg/ml) since this β-lactamase retained a higher inactivation efficacy by avibactam in comparison to AmpCcloacae N346Y. For FOX-3, the I346Y substitution did not reduce the inactivation efficacy of avibactam and the substitution was highly deleterious for β-lactam hydrolysis, including ceftazidime, preventing CAZ-AVI resistance. Since AmpCcloacae and DHA-1 display substantial sequence diversity, our results suggest that loss of hydrogen interaction between Asn346 and avibactam could be a common mechanism of acquisition of CAZ-AVI resistance.


2005 ◽  
Vol 187 (15) ◽  
pp. 5242-5248 ◽  
Author(s):  
Saori Kosono ◽  
Koki Haga ◽  
Rui Tomizawa ◽  
Yusuke Kajiyama ◽  
Kazuo Hatano ◽  
...  

ABSTRACT Sha (also known as Mrp/Mnh/Pha) is a Na+/H+ antiporter encoded by a cluster of six or seven genes that probably form a multisubunit transport complex. The Sha system is important for the homeostasis of H+, Na+, and other monovalent cations and plays a critical role in various functions, including alkaliphily, sporulation, and symbiosis. Here, we characterized the sha homologue genes from the opportunistic pathogen Pseudomonas aeruginosa, which exist as a cluster of six genes (PA1054 to PA1059). The gene cluster PA1054 to PA1059, but not the cluster with a deletion of PA1054, complemented a growth defect in the presence of 0.2 M NaCl and a defect in Na+/H+ antiport activity of the Escherichia coli TO114 mutant lacking the three major Na+/H+ antiporters, indicating that genes PA1054 to PA1059 are responsible for Na+/H+ antiport activity. We disrupted PA1054 (a shaA homologue gene) and determined its effect on Na+ tolerance during growth, Na+ efflux, and pathogenicity in mice. Disruption of PA1054 resulted in severe Na+ sensitivity during growth and decreased Na+ efflux activity. In mice, the deletion mutant of PA1054 also exhibited an attenuated virulence in systemic, pulmonary, and urinary tract infections and also a decrease in colonization of the infected organs. From these results, we conclude that the genes PA1054 to PA1059 encode a Na+/H+ antiporter that is largely responsible for Na+ extrusion in P. aeruginosa and has a role in the infection of the pathogen. We propose to designate PA1054 to PA1059 as the sha (sodium hydrogen antiporter) genes, shaABCDEFG.


2016 ◽  
Vol 82 (22) ◽  
pp. 6541-6547 ◽  
Author(s):  
Indira Cruz-Plancarte ◽  
Adrián Cazares ◽  
Gabriel Guarneros

ABSTRACTPreviously, a collection of virulent phages infectingPseudomonas aeruginosawas isolated from open water reservoirs and residual waters. Here, we described the comparative genomics of a set of five related phages from the collection, the physical structure of the genome, the structural proteomics of the virion, and the transcriptional program of archetypal phage PaMx41. The phage genomes were closely associated with each other and with those of two otherP. aeruginosaphages, 119X and PaP2, which were previously filed in the databases. Overall, the genomes were approximately 43 kb, harboring 53 conserved open reading frames (ORFs) and three short ORFs in indel regions and containing 45% GC content. The genome of PaMx41 was further characterized as a linear, terminally redundant DNA molecule. A total of 16 ORFs were associated with putative functions, including nucleic acid metabolism, morphogenesis, and lysis, and eight virion proteins were identified through mass spectrometry. However, the coding sequences without assigned functions represent 70% of the ORFs. The PaMx41 transcription program was organized in early, middle, and late expressed genomic modules, which correlated with regions containing functionally related genes. The high genomic conservation among these distantly isolated phages suggests that these viruses undergo selective pressure to remain unchanged. The 119X lineage represents a unique set of phages that corresponds to a novel phage group. The features recognized in the genomes and the broad host range of clinical strains suggest that these phages are candidates for therapy applications.IMPORTANCEPseudomonas aeruginosais an opportunistic pathogen that causes stubborn nosocomial infections that are frequently resistant to multiple antibiotics. Bacterial viruses (bacteriophages or phages) represent a natural mechanism for pathogenic bacterial control. Here, a group of virulent phages, previously shown to infect a broad range of clinicalP. aeruginosastrains, was characterized at the genomic and molecular levels. These phages belong to a unique and tightly related group. In addition, we conducted a transcriptional study of an archetypal phage of this group to characterize the role of many unknown coding sequences based on expression temporalities. These results contribute to our knowledge of 119X-like phages and, in general, provide information concerningP. aeruginosapodophage diversity and lytic cycles.


2018 ◽  
Vol 200 (12) ◽  
Author(s):  
Alice Berry ◽  
Kook Han ◽  
Julian Trouillon ◽  
Mylène Robert-Genthon ◽  
Michel Ragno ◽  
...  

ABSTRACT The two-partner secretion system ExlBA, expressed by strains of Pseudomonas aeruginosa belonging to the PA7 group, induces hemorrhage in lungs due to disruption of host cellular membranes. Here we demonstrate that the exlBA genes are controlled by a pathway consisting of cAMP and the virulence factor regulator (Vfr). Upon interaction with cAMP, Vfr binds directly to the exlBA promoter with high affinity (equilibrium binding constant [ K eq ] of ≈2.5 nM). The exlB and exlA expression was diminished in the Vfr-negative mutant and upregulated with increased intracellular cAMP levels. The Vfr binding sequence in the exlBA promoter was mutated in situ , resulting in reduced cytotoxicity of the mutant, showing that Vfr is required for the exlBA expression during intoxication of epithelial cells. Vfr also regulates function of type 4 pili previously shown to facilitate ExlA activity on epithelial cells, which indicates that the cAMP/Vfr pathway coordinates these two factors needed for full cytotoxicity. As in most P. aeruginosa strains, the adenylate cyclase CyaB is the main provider of cAMP for Vfr regulation during both in vitro growth and eukaryotic cell infection. We discovered that the absence of functional Vfr in the reference strain PA7 is caused by a frameshift in the gene and accounts for its reduced cytotoxicity, revealing the conservation of ExlBA control by the CyaB-cAMP/Vfr pathway in P. aeruginosa taxonomic outliers. IMPORTANCE The human opportunistic pathogen Pseudomonas aeruginosa provokes severe acute and chronic human infections associated with defined sets of virulence factors. The main virulence determinant of P. aeruginosa taxonomic outliers is exolysin, a membrane-disrupting pore-forming toxin belonging to the two-partner secretion system ExlBA. In this work, we demonstrate that the conserved CyaB-cAMP/Vfr pathway controls cytotoxicity of outlier clinical strains through direct transcriptional activation of the exlBA operon. Therefore, despite the fact that the type III secretion system and exolysin are mutually exclusive in classical and outlier strains, respectively, these two major virulence determinants share similarities in their mechanisms of regulation.


2019 ◽  
Vol 8 (13) ◽  
Author(s):  
Julie Jeukens ◽  
Jean-Guillaume Emond-Rheault ◽  
Luca Freschi ◽  
Irena Kukavica-Ibrulj ◽  
Roger C. Levesque

Pseudomonas aeruginosa is an environmental bacterium and opportunistic pathogen. Here, we present draft genome sequences for 161 isolates from diverse clinical and environmental sources.


mSystems ◽  
2018 ◽  
Vol 3 (5) ◽  
Author(s):  
Whitney E. England ◽  
Ted Kim ◽  
Rachel J. Whitaker

ABSTRACTViruses that infect the widespread opportunistic pathogenPseudomonas aeruginosahave been shown to influence physiology and critical clinical outcomes in cystic fibrosis (CF) patients. To understand how CRISPR-Cas immune interactions may contribute to the distribution and coevolution ofP. aeruginosaand its viruses, we reconstructed CRISPR arrays from a highly sampled longitudinal data set from CF patients attending the Copenhagen Cystic Fibrosis Clinic in Copenhagen, Denmark (R. L. Marvig, L. M. Sommer, S. Molin, and H. K. Johansen, Nat Genet 47:57–64, 2015,https://doi.org/10.1038/ng.3148). We show that new spacers are not added to or deleted from CRISPR arrays over time within a single patient but do vary among patients in this data set. We compared assembled CRISPR arrays from this data set to CRISPR arrays extracted from 726 additional publicly availableP. aeruginosasequences to show that local diversity in this population encompasses global diversity and that there is no evidence for population structure associated with location or environment sampled. We compare over 3,000 spacers from our global data set to 98 lytic and temperate viruses and proviruses and find a subset of related temperate virus clusters frequently targeted by CRISPR spacers. Highly targeted viruses are matched by different spacers in different arrays, resulting in a pattern of distributed immunity within the global population. Understanding the multiple immune contexts thatP. aeruginosaviruses face can be applied to study ofP. aeruginosagene transfer, the spread of epidemic strains in cystic fibrosis patients, and viral control ofP. aeruginosainfection.IMPORTANCEPseudomonas aeruginosais a widespread opportunistic pathogen and a major cause of morbidity and mortality in cystic fibrosis patients. Microbe-virus interactions play a critical role in shaping microbial populations, as viral infections can kill microbial populations or contribute to gene flow among microbes. Investigating howP. aeruginosauses its CRISPR immune system to evade viral infection aids our understanding of how this organism spreads and evolves alongside its viruses in humans and the environment. Here, we identify patterns of CRISPR targeting and immunity that indicateP. aeruginosaand its viruses evolve in both a broad global population and in isolated human “islands.” These data set the stage for exploring metapopulation dynamics occurring within and between isolated “island” populations associated with CF patients, an essential step to inform future work predicting the specificity and efficacy of virus therapy and the spread of invasive viral elements and pathogenic epidemic bacterial strains.


2019 ◽  
Vol 201 (23) ◽  
Author(s):  
Jean-Louis Bru ◽  
Brandon Rawson ◽  
Calvin Trinh ◽  
Katrine Whiteson ◽  
Nina Molin Høyland-Kroghsbo ◽  
...  

ABSTRACT We investigate the effect of bacteriophage infection and antibiotic treatment on the coordination of swarming, a collective form of flagellum- and pilus-mediated motility in bacteria. We show that phage infection of the opportunistic bacterial pathogen Pseudomonas aeruginosa abolishes swarming motility in the infected subpopulation and induces the release of the Pseudomonas quinolone signaling molecule PQS, which repulses uninfected subpopulations from approaching the infected area. These mechanisms have the overall effect of limiting the infection to a subpopulation, which promotes the survival of the overall population. Antibiotic treatment of P. aeruginosa elicits the same response, abolishing swarming motility and repulsing approaching swarms away from the antibiotic-treated area through a PQS-dependent mechanism. Swarms are entirely repelled from the zone of antibiotic-treated P. aeruginosa, consistent with a form of antibiotic evasion, and are not repelled by antibiotics alone. PQS has multiple functions, including serving as a quorum-sensing molecule, activating an oxidative stress response, and regulating the release of virulence and host-modifying factors. We show that PQS serves additionally as a stress warning signal that causes the greater population to physically avoid cell stress. The stress response at the collective level observed here in P. aeruginosa is consistent with a mechanism that promotes the survival of bacterial populations. IMPORTANCE We uncover a phage- and antibiotic-induced stress response in the clinically important opportunistic pathogen Pseudomonas aeruginosa. Phage-infected P. aeruginosa subpopulations are isolated from uninfected subpopulations by the production of a stress-induced signal. Activation of the stress response by antibiotics causes P. aeruginosa to physically be repelled from the area containing antibiotics altogether, consistent with a mechanism of antibiotic evasion. The stress response observed here could increase P. aeruginosa resilience against antibiotic treatment and phage therapy in health care settings, as well as provide a simple evolutionary strategy to avoid areas containing stress.


Sign in / Sign up

Export Citation Format

Share Document