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Hernández Delgado JG, Acedos MG, de la Calle F, Rodríguez P, García JL, Galán B. Regulation of Safracin Biosynthesis and Transport in Pseudomonas poae PMA22. Mar Drugs 2024; 22:418. [PMID: 39330299 PMCID: PMC11432991 DOI: 10.3390/md22090418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2024] [Revised: 09/06/2024] [Accepted: 09/10/2024] [Indexed: 09/28/2024] Open
Abstract
Pseudomonas poae PMA22 produces safracins, a family of compounds with potent broad-spectrum anti-bacterial and anti-tumor activities. The safracins' biosynthetic gene cluster (BGC sac) consists of 11 ORFs organized in two divergent operons (sacABCDEFGHK and sacIJ) that are controlled by Pa and Pi promoters. Contiguous to the BGC sac, we have located a gene that encodes a putative global regulator of the LysR family annotated as MexT that was originally described as a transcriptional activator of the MexEF-OprN multidrug efflux pump in Pseudomonas. Through both in vitro and in vivo experiments, we have demonstrated the involvement of the dual regulatory system MexT-MexS on the BGC sac expression acting as an activator and a repressor, respectively. The MexEF-OprN transport system of PMA22, also controlled by MexT, was shown to play a fundamental role in the metabolism of safracin. The overexpression of mexEF-oprN in PMA22 resulted in fourfold higher production levels of safracin. These results illustrate how a pleiotropic regulatory system can be critical to optimizing the production of tailored secondary metabolites, not only through direct interaction with the BGC promoters, but also by controlling their transport.
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Affiliation(s)
- J Gerardo Hernández Delgado
- Department of Biothecnology, Centro de Investigaciones Biológicas Margarita Salas, Agencia Estatal Consejo Superior de Investigaciones Científicas (CSIC), 28040 Madrid, Spain
| | - Miguel G Acedos
- Department of Biothecnology, Centro de Investigaciones Biológicas Margarita Salas, Agencia Estatal Consejo Superior de Investigaciones Científicas (CSIC), 28040 Madrid, Spain
| | | | - Pilar Rodríguez
- Research and Development Department, PharmaMar S.A., 28770 Madrid, Spain
| | - José Luis García
- Department of Biothecnology, Centro de Investigaciones Biológicas Margarita Salas, Agencia Estatal Consejo Superior de Investigaciones Científicas (CSIC), 28040 Madrid, Spain
| | - Beatriz Galán
- Department of Biothecnology, Centro de Investigaciones Biológicas Margarita Salas, Agencia Estatal Consejo Superior de Investigaciones Científicas (CSIC), 28040 Madrid, Spain
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2
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Lechtenberg T, Wynands B, Müller MF, Polen T, Noack S, Wierckx N. Improving 5-(hydroxymethyl)furfural (HMF) tolerance of Pseudomonas taiwanensis VLB120 by automated adaptive laboratory evolution (ALE). Metab Eng Commun 2024; 18:e00235. [PMID: 38832093 PMCID: PMC11144800 DOI: 10.1016/j.mec.2024.e00235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Revised: 04/29/2024] [Accepted: 05/07/2024] [Indexed: 06/05/2024] Open
Abstract
The aldehyde 5-(hydroxymethyl)furfural (HMF) is of great importance for a circular bioeconomy. It is a renewable platform chemical that can be converted into a range of useful compounds to replace petroleum-based products such as the green plastic monomer 2,5-furandicarboxylic acid (FDCA). However, it also exhibits microbial toxicity for example hindering the efficient biotechnological valorization of lignocellulosic hydrolysates. Thus, there is an urgent need for tolerance-improved organisms applicable to whole-cell biocatalysis. Here, we engineer an oxidation-deficient derivative of the naturally robust and emerging biotechnological workhorse P. taiwanensis VLB120 by robotics-assisted adaptive laboratory evolution (ALE). The deletion of HMF-oxidizing enzymes enabled for the first time evolution under constant selection pressure by the aldehyde, yielding strains with consistently improved growth characteristics in presence of the toxicant. Genome sequencing of evolved clones revealed loss-of function mutations in the LysR-type transcriptional regulator-encoding mexT preventing expression of the associated efflux pump mexEF-oprN. This knowledge allowed reverse engineering of strains with enhanced aldehyde tolerance, even in a background of active or overexpressed HMF oxidation machinery, demonstrating a synergistic effect of two distinct tolerance mechanisms.
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Affiliation(s)
- Thorsten Lechtenberg
- Institute of Bio- and Geosciences IBG-1: Biotechnology, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Benedikt Wynands
- Institute of Bio- and Geosciences IBG-1: Biotechnology, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Moritz-Fabian Müller
- Institute of Bio- and Geosciences IBG-1: Biotechnology, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Tino Polen
- Institute of Bio- and Geosciences IBG-1: Biotechnology, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Stephan Noack
- Institute of Bio- and Geosciences IBG-1: Biotechnology, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Nick Wierckx
- Institute of Bio- and Geosciences IBG-1: Biotechnology, Forschungszentrum Jülich, 52425 Jülich, Germany
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3
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Jing FH, Wang Q, He TJ, Xin N, Wang YW, Han Y, Wang X, Li Z. Three-Year Point Prevalence Survey of Antimicrobial Use in a Chinese University Hospital. THE CANADIAN JOURNAL OF INFECTIOUS DISEASES & MEDICAL MICROBIOLOGY = JOURNAL CANADIEN DES MALADIES INFECTIEUSES ET DE LA MICROBIOLOGIE MEDICALE 2024; 2024:6698387. [PMID: 38361762 PMCID: PMC10869184 DOI: 10.1155/2024/6698387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 11/28/2023] [Accepted: 02/01/2024] [Indexed: 02/17/2024]
Abstract
To evaluate the prevalence and quality of antimicrobial prescriptions using a Global Point Prevalence Survey (PPS) tool and help identify targets for improvement of antimicrobial prescribing and inform the development of antimicrobial stewardship activities. Antimicrobial prescriptions for inpatients staying at a hospital overnight were surveyed on one weekday in October 2018, November 2019, and November 2020. Data including basic patient information, antimicrobial drugs, quality evaluation of antimicrobial drug prescription, and the risk factors of nosocomial infection were collected from doctor network workstation. Patient information was anonymized and entered in the PPS Web application by physicians. A total of 720 patients (median age, 62 years) were surveyed. Of them, 246 (34.2%) were prescribed antimicrobials on the survey days. Hospital-wide antimicrobial use had a significantly decreasing trend (P < 0.001). The most commonly prescribed antimicrobial drugs were third-generation cephalosporins (40.5%), followed by quinolones (21.8%) and second-generation cephalosporin (12.5%). In our study, cefoperazone/sulbactam, ceftazidime, and levofloxacin were the most commonly used antimicrobials. The most common indication for antimicrobial use was pneumonia or lower respiratory tract infection (159/321, 49.5%). Antimicrobial for surgical prophylaxis represented 16.2% of the total antibiotic doses. Of those, 67.3% were administered for more than 24 h. The rate of adherence to antibiotic guidelines was 61.4%. The indications for antimicrobials were not documented in 54.5% of the prescriptions. Stop/review date was documented for 36.8% of prescriptions. The PPS tool is useful in identifying targets to enhance the quality of antimicrobial prescriptions to improve the adherence rate in hospitals. This survey can be used as a control to assess the rational application quality of antimicrobial after regular application of antimicrobial intervention.
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Affiliation(s)
- Fa-Hong Jing
- Department of Laboratory Medicine, The First Affiliated Hospital of Xi'an Medical University, Xi'an 710077, China
| | - Qiang Wang
- Department of Infection Management, The First Affiliated Hospital of Xi'an Medical University, Xi'an 710077, China
| | - Tian-Jiao He
- Department of Laboratory Medicine, The First Affiliated Hospital of Xi'an Medical University, Xi'an 710077, China
| | - Na Xin
- Department of Laboratory Medicine, The First Affiliated Hospital of Xi'an Medical University, Xi'an 710077, China
| | - Yao-Wei Wang
- Department of Laboratory Medicine, The First Affiliated Hospital of Xi'an Medical University, Xi'an 710077, China
| | - Yang Han
- Department of Laboratory Medicine, The First Affiliated Hospital of Xi'an Medical University, Xi'an 710077, China
| | - Xin Wang
- Department of Laboratory Medicine, The First Affiliated Hospital of Xi'an Medical University, Xi'an 710077, China
| | - Zhuo Li
- Department of Laboratory Medicine, The First Affiliated Hospital of Xi'an Medical University, Xi'an 710077, China
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Kristensen R, Andersen JB, Rybtke M, Jansen CU, Fritz BG, Kiilerich RO, Uhd J, Bjarnsholt T, Qvortrup K, Tolker-Nielsen T, Givskov M, Jakobsen TH. Inhibition of Pseudomonas aeruginosa quorum sensing by chemical induction of the MexEF-oprN efflux pump. Antimicrob Agents Chemother 2024; 68:e0138723. [PMID: 38189278 PMCID: PMC10848761 DOI: 10.1128/aac.01387-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Accepted: 11/17/2023] [Indexed: 01/09/2024] Open
Abstract
The cell-to-cell communication system quorum sensing (QS), used by various pathogenic bacteria to synchronize gene expression and increase host invasion potentials, is studied as a potential target for persistent infection control. To search for novel molecules targeting the QS system in the Gram-negative opportunistic pathogen Pseudomonas aeruginosa, a chemical library consisting of 3,280 small compounds from LifeArc was screened. A series of 10 conjugated phenones that have not previously been reported to target bacteria were identified as inhibitors of QS in P. aeruginosa. Two lead compounds (ethylthio enynone and propylthio enynone) were re-synthesized for verification of activity and further elucidation of the mode of action. The isomeric pure Z-ethylthio enynone was used for RNA sequencing, revealing a strong inhibitor of QS-regulated genes, and the QS-regulated virulence factors rhamnolipid and pyocyanin were significantly decreased by treatment with the compounds. A transposon mutagenesis screen performed in a newly constructed lasB-gfp monitor strain identified the target of Z-ethylthio enynone in P. aeruginosa to be the MexEF-OprN efflux pump, which was further established using defined mex knockout mutants. Our data indicate that the QS inhibitory capabilities of Z-ethylthio enynone were caused by the drainage of intracellular signal molecules as a response to chemical-induced stimulation of the MexEF-oprN efflux pump, thereby inhibiting the autogenerated positive feedback and its enhanced signal-molecule synthesis.
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Affiliation(s)
- Rasmus Kristensen
- Department of Immunology and Microbiology, Costerton Biofilm Center, University of Copenhagen, Copenhagen, Denmark
| | - Jens Bo Andersen
- Department of Immunology and Microbiology, Costerton Biofilm Center, University of Copenhagen, Copenhagen, Denmark
| | - Morten Rybtke
- Department of Immunology and Microbiology, Costerton Biofilm Center, University of Copenhagen, Copenhagen, Denmark
| | | | - Blaine Gabriel Fritz
- Department of Immunology and Microbiology, Costerton Biofilm Center, University of Copenhagen, Copenhagen, Denmark
| | - Rikke Overgaard Kiilerich
- Department of Immunology and Microbiology, Costerton Biofilm Center, University of Copenhagen, Copenhagen, Denmark
| | - Jesper Uhd
- Department of Chemistry, Technical University of Denmark, Lyngby, Denmark
| | - Thomas Bjarnsholt
- Department of Immunology and Microbiology, Costerton Biofilm Center, University of Copenhagen, Copenhagen, Denmark
- Department of Clinical Microbiology, Rigshospitalet, Copenhagen, Denmark
| | - Katrine Qvortrup
- Department of Chemistry, Technical University of Denmark, Lyngby, Denmark
| | - Tim Tolker-Nielsen
- Department of Immunology and Microbiology, Costerton Biofilm Center, University of Copenhagen, Copenhagen, Denmark
| | - Michael Givskov
- Department of Immunology and Microbiology, Costerton Biofilm Center, University of Copenhagen, Copenhagen, Denmark
| | - Tim Holm Jakobsen
- Department of Immunology and Microbiology, Costerton Biofilm Center, University of Copenhagen, Copenhagen, Denmark
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Deery J, Carmody M, Flavin R, Tomanek M, O'Keeffe M, McGlacken GP, Reen FJ. Comparative genomics reveals distinct diversification patterns among LysR-type transcriptional regulators in the ESKAPE pathogen Pseudomonas aeruginosa. Microb Genom 2024; 10:001205. [PMID: 38421269 PMCID: PMC10926688 DOI: 10.1099/mgen.0.001205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Accepted: 02/06/2024] [Indexed: 03/02/2024] Open
Abstract
Pseudomonas aeruginosa, a harmful nosocomial pathogen associated with cystic fibrosis and burn wounds, encodes for a large number of LysR-type transcriptional regulator proteins. To understand how and why LTTR proteins evolved with such frequency and to establish whether any relationships exist within the distribution we set out to identify the patterns underpinning LTTR distribution in P. aeruginosa and to uncover cluster-based relationships within the pangenome. Comparative genomic studies revealed that in the JGI IMG database alone ~86 000 LTTRs are present across the sequenced genomes (n=699). They are widely distributed across the species, with core LTTRs present in >93 % of the genomes and accessory LTTRs present in <7 %. Analysis showed that subsets of core LTTRs can be classified as either variable (typically specific to P. aeruginosa) or conserved (and found to be distributed in other Pseudomonas species). Extending the analysis to the more extensive Pseudomonas database, PA14 rooted analysis confirmed the diversification patterns and revealed PqsR, the receptor for the Pseudomonas quinolone signal (PQS) and 2-heptyl-4-quinolone (HHQ) quorum-sensing signals, to be amongst the most variable in the dataset. Successful complementation of the PAO1 pqsR - mutant using representative variant pqsR sequences suggests a degree of structural promiscuity within the most variable of LTTRs, several of which play a prominent role in signalling and communication. These findings provide a new insight into the diversification of LTTR proteins within the P. aeruginosa species and suggests a functional significance to the cluster, conservation and distribution patterns identified.
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Affiliation(s)
- Jamie Deery
- School of Microbiology, University College Cork, Cork, Ireland
| | - Muireann Carmody
- School of Microbiology, University College Cork, Cork, Ireland
- School of Chemistry, University College Cork, Cork, Ireland
| | - Rhiannon Flavin
- School of Microbiology, University College Cork, Cork, Ireland
| | - Malwina Tomanek
- School of Microbiology, University College Cork, Cork, Ireland
| | - Maria O'Keeffe
- School of Microbiology, University College Cork, Cork, Ireland
| | - Gerard P. McGlacken
- School of Chemistry, University College Cork, Cork, Ireland
- Synthesis and Solid State Pharmaceutical Centre, University College Cork, Cork, Ireland
| | - F. Jerry Reen
- School of Microbiology, University College Cork, Cork, Ireland
- Synthesis and Solid State Pharmaceutical Centre, University College Cork, Cork, Ireland
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6
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Zhou Z, Lian Y, Zhu L, Zhang H, Li Z, Wang M. Platinum Nanoparticles Prevent the Resistance of Pseudomonas aeruginosa to Ciprofloxacin and Imipenem: Mechanism Insights. ACS NANO 2023; 17:24685-24695. [PMID: 38048441 DOI: 10.1021/acsnano.3c04167] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/06/2023]
Abstract
Metal nanoparticles (MNPs) have recently gained extensive attention due to their broad-spectrum prospect, particularly in biomedical application. Here, we reveal that long-term exposure to platinum nanoparticles (Pt NPs) increases the susceptibility of Pseudomonas aeruginosa PAO1 to imipenem and ciprofloxacin. We exposed PAO1 to Pt NPs (a series of doses, varying from 0.125 to 35 μg/mL) for 60 days and characterized the evolved strains (ES) and compared with wild type (WT) to understand the mechanism of heightened sensitivity. We found that overexpression of oprD and downregulation of mexEF-oprN facilitate the intracellular accumulation of antibiotic, thus increasing susceptibility. Furthermore, loss-of-function mutations were discovered in regulators lasR and mexT. Cloning intact lasR from wild-type (WT) into ES slightly improves imipenem resistance. Strikingly, cloning mexT from WT into ES reverts the imipenem and ciprofloxacin resistance to the original level. Briefly, the increase of membrane permeability controlled by mexT made PAO1 greatly susceptible to imipenem and ciprofloxacin, and the decrease of quorum sensing mediated by lasR made PAO1 slightly susceptible to imipenem. Overall, these results reveal an antibiotic susceptibility mechanism from prolonged exposure to MNPs, which provides a promising approach to prevent antibiotic resistance.
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Affiliation(s)
- Zhiruo Zhou
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012, China
| | - Yulu Lian
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012, China
| | - Lin Zhu
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012, China
| | - Haibo Zhang
- China National Demonstration Center for Experimental Chemistry, Wuhan University, Wuhan 430072, China
| | - Zhangqiang Li
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012, China
| | - Meizhen Wang
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012, China
- Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou 310012, China
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7
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Kostylev M, Smalley NE, Chao MH, Greenberg EP. Relationship of the transcription factor MexT to quorum sensing and virulence in Pseudomonas aeruginosa. J Bacteriol 2023; 205:e0022623. [PMID: 38032211 PMCID: PMC10729655 DOI: 10.1128/jb.00226-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Accepted: 11/09/2023] [Indexed: 12/01/2023] Open
Abstract
IMPORTANCE Pseudomonas aeruginosa is an opportunistic bacterial pathogen. Many of its virulence genes are regulated by quorum sensing (QS), a form of cell-to-cell communication. P. aeruginosa QS consists of three interlinked circuits, LasI-R, Rhl-R, and Pseudomonas quinolone signal (PQS). Additionally, its QS system is interconnected with other regulatory networks, which help optimize gene expression under variable conditions. The numbers of genes regulated by QS differ substantially among P. aeruginosa strains. We show that a regulatory factor MexT, which is activated in response to certain antibiotics, downregulates the RhlI-R circuit and in turn measurably lowers virulence in a nematode worm infection model. Our findings help understand how existing and future therapeutic interventions for P. aeruginosa infections may impact this bacterium's gene regulation and physiology.
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Affiliation(s)
- Maxim Kostylev
- Department of Microbiology, University of Washington School of Medicine, Seattle, Washington, USA
| | - Nicole E. Smalley
- Department of Microbiology, University of Washington School of Medicine, Seattle, Washington, USA
| | - Man Hou Chao
- Department of Microbiology, University of Washington School of Medicine, Seattle, Washington, USA
| | - E. Peter Greenberg
- Department of Microbiology, University of Washington School of Medicine, Seattle, Washington, USA
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8
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Cai W, Liao H, Lu M, Zhou X, Cheng X, Staehelin C, Dai W. New Evolutionary Insights into RpoA: A Novel Quorum Sensing Reprograming Factor in Pseudomonas aeruginosa. Mol Biol Evol 2023; 40:msad203. [PMID: 37708386 PMCID: PMC10566545 DOI: 10.1093/molbev/msad203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 08/19/2023] [Accepted: 08/22/2023] [Indexed: 09/16/2023] Open
Abstract
Quorum-sensing (QS) coordinates the expression of virulence factors in Pseudomonas aeruginosa, an opportunistic pathogen known for causing severe infections in immunocompromised patients. QS has a master regulator, the lasR gene, but in clinical settings, P. aeruginosa isolates have been found that are QS-active but LasR-null. In this study, we developed an experimental evolutionary approach to identify additional QS-reprogramming determinants. We began the study with a LasR-null mutant with an extra copy of mexT, a transcriptional regulator gene that is known to be able to reprogram QS in laboratory LasR-null strains. In this strain, spontaneous single mexT mutations are expected to have no or little phenotypic consequences. Using this novel method, which we have named "targeted gene duplication followed by mutant screening", we identified QS-active revertants with mutations in genes other than mexT. One QS-active revertant had a point mutation in rpoA, a gene encoding the α-subunit of RNA polymerase. QS activation in this mutant was found to be associated with the downregulated expression of mexEF-oprN efflux pump genes. Our study therefore uncovers a new functional role for RpoA in regulating QS activity. Our results indicate that a RpoA-dependent regulatory circuit controlling the expression of the mexEF-oprN operon is critical for QS-reprogramming. In conclusion, our study reports on the identification of non-MexT proteins associated with QS-reprogramming in a laboratory strain, shedding light on possible QS activation mechanisms in clinical P. aeruginosa isolates.
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Affiliation(s)
- Wenjie Cai
- Guangdong Laboratory for Lingnan Modern Agriculture, South China Agricultural University, Guangzhou, China
- College of Plant Protection, Integrative Microbiology Research Center, South China Agricultural University, Guangzhou, China
| | - Huimin Liao
- Guangdong Laboratory for Lingnan Modern Agriculture, South China Agricultural University, Guangzhou, China
- College of Plant Protection, Integrative Microbiology Research Center, South China Agricultural University, Guangzhou, China
| | - Mingqi Lu
- Guangdong Laboratory for Lingnan Modern Agriculture, South China Agricultural University, Guangzhou, China
- College of Plant Protection, Integrative Microbiology Research Center, South China Agricultural University, Guangzhou, China
| | - Xiangting Zhou
- Guangdong Laboratory for Lingnan Modern Agriculture, South China Agricultural University, Guangzhou, China
- College of Plant Protection, Integrative Microbiology Research Center, South China Agricultural University, Guangzhou, China
| | - Xiaoyan Cheng
- Guangdong Laboratory for Lingnan Modern Agriculture, South China Agricultural University, Guangzhou, China
- College of Plant Protection, Integrative Microbiology Research Center, South China Agricultural University, Guangzhou, China
| | - Christian Staehelin
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Weijun Dai
- Guangdong Laboratory for Lingnan Modern Agriculture, South China Agricultural University, Guangzhou, China
- College of Plant Protection, Integrative Microbiology Research Center, South China Agricultural University, Guangzhou, China
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9
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Jordana-Lluch E, Barceló IM, Escobar-Salom M, Estévez MA, Zamorano L, Gómez-Zorrilla S, Sendra E, Oliver A, Juan C. The balance between antibiotic resistance and fitness/virulence in Pseudomonas aeruginosa: an update on basic knowledge and fundamental research. Front Microbiol 2023; 14:1270999. [PMID: 37840717 PMCID: PMC10569695 DOI: 10.3389/fmicb.2023.1270999] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Accepted: 09/15/2023] [Indexed: 10/17/2023] Open
Abstract
The interplay between antibiotic resistance and bacterial fitness/virulence has attracted the interest of researchers for decades because of its therapeutic implications, since it is classically assumed that resistance usually entails certain biological costs. Reviews on this topic revise the published data from a general point of view, including studies based on clinical strains or in vitro-evolved mutants in which the resistance phenotype is seen as a final outcome, i.e., a combination of mechanisms. However, a review analyzing the resistance/fitness balance from the basic research perspective, compiling studies in which the different resistance pathways and respective biological costs are individually approached, was missing. Here we cover this gap, specifically focusing on Pseudomonas aeruginosa, a pathogen that stands out because of its extraordinary capacity for resistance development and for which a considerable number of recent and particular data on the interplay with fitness/virulence have been released. The revised information, split into horizontally-acquired vs. mutation-driven resistance, suggests a great complexity and even controversy in the resistance-fitness/virulence balance in the acute infection context, with results ranging from high costs linked to certain pathways to others that are seemingly cost-free or even cases of resistance mechanisms contributing to increased pathogenic capacities. The elusive mechanistic basis for some enigmatic data, knowledge gaps, and possibilities for therapeutic exploitation are discussed. The information gathered suggests that resistance-fitness/virulence interplay may be a source of potential antipseudomonal targets and thus, this review poses the elementary first step for the future development of these strategies harnessing certain resistance-associated biological burdens.
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Affiliation(s)
- Elena Jordana-Lluch
- Research Unit, University Hospital Son Espases-Health Research Institute of the Balearic Islands (IdISBa), Palma, Spain
- Department of Microbiology, University Hospital Son Espases, Palma, Spain
- Centro de Investigación Biomédica en Red, Enfermedades Infecciosas (CIBERINFEC), Madrid, Spain
| | - Isabel Mª Barceló
- Research Unit, University Hospital Son Espases-Health Research Institute of the Balearic Islands (IdISBa), Palma, Spain
- Department of Microbiology, University Hospital Son Espases, Palma, Spain
- Centro de Investigación Biomédica en Red, Enfermedades Infecciosas (CIBERINFEC), Madrid, Spain
| | - María Escobar-Salom
- Research Unit, University Hospital Son Espases-Health Research Institute of the Balearic Islands (IdISBa), Palma, Spain
- Department of Microbiology, University Hospital Son Espases, Palma, Spain
- Centro de Investigación Biomédica en Red, Enfermedades Infecciosas (CIBERINFEC), Madrid, Spain
| | - Miguel A. Estévez
- Research Unit, University Hospital Son Espases-Health Research Institute of the Balearic Islands (IdISBa), Palma, Spain
- Department of Microbiology, University Hospital Son Espases, Palma, Spain
| | - Laura Zamorano
- Research Unit, University Hospital Son Espases-Health Research Institute of the Balearic Islands (IdISBa), Palma, Spain
- Department of Microbiology, University Hospital Son Espases, Palma, Spain
- Centro de Investigación Biomédica en Red, Enfermedades Infecciosas (CIBERINFEC), Madrid, Spain
| | - Silvia Gómez-Zorrilla
- Centro de Investigación Biomédica en Red, Enfermedades Infecciosas (CIBERINFEC), Madrid, Spain
- Infectious Diseases Service, Hospital del Mar, Hospital del Mar Research Institute, Barcelona, Spain
- Universitat Pompeu Fabra (UPF), Universitat Autònoma de Barcelóna (UAB), Barcelona, Spain
| | - Elena Sendra
- Infectious Diseases Service, Hospital del Mar, Hospital del Mar Research Institute, Barcelona, Spain
- Universitat Pompeu Fabra (UPF), Universitat Autònoma de Barcelóna (UAB), Barcelona, Spain
| | - Antonio Oliver
- Research Unit, University Hospital Son Espases-Health Research Institute of the Balearic Islands (IdISBa), Palma, Spain
- Department of Microbiology, University Hospital Son Espases, Palma, Spain
- Centro de Investigación Biomédica en Red, Enfermedades Infecciosas (CIBERINFEC), Madrid, Spain
| | - Carlos Juan
- Research Unit, University Hospital Son Espases-Health Research Institute of the Balearic Islands (IdISBa), Palma, Spain
- Department of Microbiology, University Hospital Son Espases, Palma, Spain
- Centro de Investigación Biomédica en Red, Enfermedades Infecciosas (CIBERINFEC), Madrid, Spain
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10
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Liu Y, Ahator SD, Wang H, Feng Q, Xu Y, Li C, Zhou X, Zhang LH. Microevolution of the mexT and lasR Reinforces the Bias of Quorum Sensing System in Laboratory Strains of Pseudomonas aeruginosa PAO1. Front Microbiol 2022; 13:821895. [PMID: 35495693 PMCID: PMC9041413 DOI: 10.3389/fmicb.2022.821895] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 02/16/2022] [Indexed: 12/30/2022] Open
Abstract
The Pseudomonas aeruginosa strain PAO1 has routinely been used as a laboratory model for quorum sensing (QS). However, the microevolution of P. aeruginosa laboratory strains resulting in genetic and phenotypic variations have caused inconsistencies in QS research. To investigate the underlying causes of these variations, we analyzed 5 Pseudomonas aeruginosa PAO1 sublines from our laboratory using a combination of phenotypic characterization, high throughput genome sequencing, and bioinformatic analysis. The major phenotypic variations among the sublines spanned across the levels of QS signals and virulence factors such as pyocyanin and elastase. Furthermore, the sublines exhibited distinct variations in motility and biofilm formation. Most of the phenotypic variations were mapped to mutations in the lasR and mexT, which are key components of the QS circuit. By introducing these mutations in the subline PAO1-E, which is devoid of such mutations, we confirmed their influence on QS, virulence, motility, and biofilm formation. The findings further highlight a possible divergent regulatory mechanism between the LasR and MexT in the P. aeruginosa. The results of our study reveal the effects of microevolution on the reproducibility of most research data from QS studies and further highlight mexT as a key component of the QS circuit of P. aeruginosa.
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Affiliation(s)
- Yang Liu
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China.,Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM) - Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Madrid, Spain
| | - Stephen Dela Ahator
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China.,Research group for Host Microbe Interactions, Department of Medical Biology, Faculty of Health Sciences, UiT The Arctic University of Norway, Tromsø, Norway
| | - Huishan Wang
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Qishun Feng
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Yinuo Xu
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Chuhao Li
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Xiaofan Zhou
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Lian-Hui Zhang
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
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11
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Liu XX, Liu L, Song X, Wang GQ, Xiong ZQ, Xia YJ, Ai LZ. Determination of the regulatory network and function of the lysR-type transcriptional regulator of Lactiplantibacillus plantarum, LpLttR. Microb Cell Fact 2022; 21:65. [PMID: 35443683 PMCID: PMC9019972 DOI: 10.1186/s12934-022-01774-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 03/12/2022] [Indexed: 11/26/2022] Open
Abstract
Background Lactiplantibacillus plantarum has various healthcare functions including the regulation of immunity and inflammation, reduction of serum cholesterol levels, anti-tumor activity, and maintenance of the balance of intestinal flora. However, the underlying metabolic and regulatory mechanisms of these processes remain unclear. Our previous studies have shown that the LysR type transcriptional regulator of L. plantarum (LpLttR) regulates the biotransformation of conjugated linoleic acids (CLAs) through the transcriptional activation of cla-dh (coding gene for CLA short-chain dehydrogenase) and cla-dc (coding gene for CLA acetoacetate decarboxylase). However, the regulatory network and function of LpLttR have not yet been characterized in L. plantarum. Results In this study, the regulatory role of LpLttR in various cellular processes was assessed using transcriptome analysis. The deletion of LpLttR had no evident influence on the bacterial growth. The transcriptome data showed that the expression of nine genes were positively regulated by LpLttR, and the expression of only two genes were negatively regulated. Through binding motif analysis and molecular interaction, we demonstrated that the regulatory region of the directly regulated genes contained a highly conserved sequence, consisting of a 15-base long box and rich in AT. Conclusion This study revealed that LpLttR of L. plantarum did not play a global regulatory role similar to that of the other transcriptional regulators in this family. This study broadens our knowledge of LpLttR and provides a theoretical basis for the utilization of L. plantarum.
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Affiliation(s)
- Xin-Xin Liu
- Shanghai Engineering Research Center of Food Microbiology, School of Health Science and Engineering, University of Shanghai for Science and Technology, Shanghai, 200093, China
| | - Lei Liu
- Shanghai Engineering Research Center of Food Microbiology, School of Health Science and Engineering, University of Shanghai for Science and Technology, Shanghai, 200093, China
| | - Xin Song
- Shanghai Engineering Research Center of Food Microbiology, School of Health Science and Engineering, University of Shanghai for Science and Technology, Shanghai, 200093, China
| | - Guang-Qiang Wang
- Shanghai Engineering Research Center of Food Microbiology, School of Health Science and Engineering, University of Shanghai for Science and Technology, Shanghai, 200093, China
| | - Zhi-Qiang Xiong
- Shanghai Engineering Research Center of Food Microbiology, School of Health Science and Engineering, University of Shanghai for Science and Technology, Shanghai, 200093, China
| | - Yong-Jun Xia
- Shanghai Engineering Research Center of Food Microbiology, School of Health Science and Engineering, University of Shanghai for Science and Technology, Shanghai, 200093, China
| | - Lian-Zhong Ai
- Shanghai Engineering Research Center of Food Microbiology, School of Health Science and Engineering, University of Shanghai for Science and Technology, Shanghai, 200093, China.
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12
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Cheng X, Lu M, Qiu H, Li Y, Huang L, Dai W. Spontaneous quorum-sensing hierarchy reprogramming in Pseudomonas aeruginosa laboratory strain PAO1. AMB Express 2022; 12:6. [PMID: 35083573 PMCID: PMC8792115 DOI: 10.1186/s13568-022-01344-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 01/01/2022] [Indexed: 11/25/2022] Open
Abstract
Pseudomonas aeruginosa strain PAO1 has been commonly used in the laboratory, with frequent genome variations reported. Quorum sensing (QS), a cell–cell communication system, plays important role in controlling a variety of virulence factors. However, the evolution and adaptability of QS in those laboratory strains are still poorly understood. Here we used the QS reporter and whole-genome sequencing (WGS) to systematically investigate the QS phenotypes and corresponding genetic basis in collected laboratory PAO1 strains. We found that the PAO1-z strain has an inactive LasR protein, while bearing an active Rhl QS system and exhibiting QS-controlled protease-positive activity. Our study revealed that an 18-bp insertion in mexT gene gave rise to the active QS system in the PAO1-z strain. This MexT inactivation restored the QS activity caused by the inactive LasR, showing elevated production of pyocyanin, cyanide and elastase. Our results implied the evolutionary trajectory for the PAO1-z strain, with the evulutionary order from the first Las QS inactivation to the final Rhl QS activation. Our findings point out that QS homeostasis occurs in the laboratory P. aeruginosa strain, offering a potential platform for the QS study in clinical isolates.
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13
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Islam MM, Kim K, Lee JC, Shin M. LeuO, a LysR-Type Transcriptional Regulator, Is Involved in Biofilm Formation and Virulence of Acinetobacter baumannii. Front Cell Infect Microbiol 2021; 11:738706. [PMID: 34708004 PMCID: PMC8543017 DOI: 10.3389/fcimb.2021.738706] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 09/23/2021] [Indexed: 12/05/2022] Open
Abstract
Acinetobacter baumannii is an important nosocomial pathogen that can survive in different environmental conditions and poses a severe threat to public health due to its multidrug resistance properties. Research on transcriptional regulators, which play an essential role in adjusting to new environments, could provide new insights into A. baumannii pathogenesis. LysR-type transcriptional regulators (LTTRs) are structurally conserved among bacterial species and regulate virulence in many pathogens. We identified a novel LTTR, designated as LeuO encoded in the A. baumannii genome. After construction of LeuO mutant strain, transcriptome analysis showed that LeuO regulates the expression of 194 upregulated genes and 108 downregulated genes responsible for various functions and our qPCR validation of several differentially expressed genes support transcriptome data. Our results demonstrated that disruption of LeuO led to increased biofilm formation and increased pathogenicity in an animal model. However, the adherence and surface motility of the LeuO mutant were reduced compared with those of the wild-type strain. We observed some mutations on amino acids sequence of LeuO in clinical isolates. These mutations in the A. baumannii biofilm regulator LeuO may cause hyper-biofilm in the tested clinical isolates. This study is the first to demonstrate the association between the LTTR member LeuO and virulence traits of A. baumannii.
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Affiliation(s)
- Md Maidul Islam
- Department of Microbiology, School of Medicine, Kyungpook National University, Daegu, South Korea
| | - Kyeongmin Kim
- Department of Microbiology, School of Medicine, Kyungpook National University, Daegu, South Korea
| | - Je Chul Lee
- Department of Microbiology, School of Medicine, Kyungpook National University, Daegu, South Korea
| | - Minsang Shin
- Department of Microbiology, School of Medicine, Kyungpook National University, Daegu, South Korea
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14
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Cianciulli Sesso A, Lilić B, Amman F, Wolfinger MT, Sonnleitner E, Bläsi U. Gene Expression Profiling of Pseudomonas aeruginosa Upon Exposure to Colistin and Tobramycin. Front Microbiol 2021; 12:626715. [PMID: 33995291 PMCID: PMC8120321 DOI: 10.3389/fmicb.2021.626715] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 03/31/2021] [Indexed: 11/22/2022] Open
Abstract
Pseudomonas aeruginosa (Pae) is notorious for its high-level resistance toward clinically used antibiotics. In fact, Pae has rendered most antimicrobials ineffective, leaving polymyxins and aminoglycosides as last resort antibiotics. Although several resistance mechanisms of Pae are known toward these drugs, a profounder knowledge of hitherto unidentified factors and pathways appears crucial to develop novel strategies to increase their efficacy. Here, we have performed for the first time transcriptome analyses and ribosome profiling in parallel with strain PA14 grown in synthetic cystic fibrosis medium upon exposure to polymyxin E (colistin) and tobramycin. This approach did not only confirm known mechanisms involved in colistin and tobramycin susceptibility but revealed also as yet unknown functions/pathways. Colistin treatment resulted primarily in an anti-oxidative stress response and in the de-regulation of the MexT and AlgU regulons, whereas exposure to tobramycin led predominantly to a rewiring of the expression of multiple amino acid catabolic genes, lower tricarboxylic acid (TCA) cycle genes, type II and VI secretion system genes and genes involved in bacterial motility and attachment, which could potentially lead to a decrease in drug uptake. Moreover, we report that the adverse effects of tobramycin on translation are countered with enhanced expression of genes involved in stalled ribosome rescue, tRNA methylation and type II toxin-antitoxin (TA) systems.
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Affiliation(s)
- Anastasia Cianciulli Sesso
- Max Perutz Labs, Vienna Biocenter (VBC), Department of Microbiology, Immunobiology and Genetics, University of Vienna, Vienna, Austria
| | - Branislav Lilić
- Max Perutz Labs, Vienna Biocenter (VBC), Department of Microbiology, Immunobiology and Genetics, University of Vienna, Vienna, Austria
| | - Fabian Amman
- Institute for Theoretical Chemistry, University of Vienna, Vienna, Austria
| | - Michael T Wolfinger
- Institute for Theoretical Chemistry, University of Vienna, Vienna, Austria.,Research Group Bioinformatics and Computational Biology, Faculty of Computer Science, University of Vienna, Vienna, Austria
| | - Elisabeth Sonnleitner
- Max Perutz Labs, Vienna Biocenter (VBC), Department of Microbiology, Immunobiology and Genetics, University of Vienna, Vienna, Austria
| | - Udo Bläsi
- Max Perutz Labs, Vienna Biocenter (VBC), Department of Microbiology, Immunobiology and Genetics, University of Vienna, Vienna, Austria
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15
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Response of Pseudomonas aeruginosa to the Innate Immune System-Derived Oxidants Hypochlorous Acid and Hypothiocyanous Acid. J Bacteriol 2020; 203:JB.00300-20. [PMID: 33106346 PMCID: PMC7950407 DOI: 10.1128/jb.00300-20] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 10/08/2020] [Indexed: 01/06/2023] Open
Abstract
The bacterial pathogen Pseudomonas aeruginosa causes devastating infections in immunocompromised hosts, including chronic lung infections in cystic fibrosis patients. To combat infection, the host’s immune system produces the antimicrobial oxidants hypochlorous acid (HOCl) and hypothiocyanous acid (HOSCN). Little is known about how P. aeruginosa responds to and survives attack from these oxidants. To address this, we carried out two approaches: a mutant screen and transcriptional study. We identified the P. aeruginosa transcriptional regulator, RclR, which responds specifically to HOCl and HOSCN stress and is essential for protection against both oxidants. We uncovered a link between the P. aeruginosa transcriptional response to these oxidants and physiological processes associated with pathogenicity, including antibiotic resistance and the type 3 secretion system. Pseudomonas aeruginosa is a significant nosocomial pathogen and is associated with lung infections in cystic fibrosis (CF). Once established, P. aeruginosa infections persist and are rarely eradicated despite host immune cells producing antimicrobial oxidants, including hypochlorous acid (HOCl) and hypothiocyanous acid (HOSCN). There is limited knowledge as to how P. aeruginosa senses, responds to, and protects itself against HOCl and HOSCN and the contribution of such responses to its success as a CF pathogen. To investigate the P. aeruginosa response to these oxidants, we screened 707 transposon mutants, with mutations in regulatory genes, for altered growth following HOCl exposure. We identified regulators of antibiotic resistance, methionine biosynthesis, catabolite repression, and PA14_07340, the homologue of the Escherichia coli HOCl-sensor RclR (30% identical), which are required for protection against HOCl. We have shown that RclR (PA14_07340) protects specifically against HOCl and HOSCN stress and responds to both oxidants by upregulating the expression of a putative peroxiredoxin, rclX (PA14_07355). Transcriptional analysis revealed that while there was specificity in the response to HOCl (231 genes upregulated) and HOSCN (105 genes upregulated), there was considerable overlap, with 74 genes upregulated by both oxidants. These included genes encoding the type 3 secretion system, sulfur and taurine transport, and the MexEF-OprN efflux pump. RclR coordinates part of the response to both oxidants, including upregulation of pyocyanin biosynthesis genes, and, in the presence of HOSCN, downregulation of chaperone genes. These data indicate that the P. aeruginosa response to HOCl and HOSCN is multifaceted, with RclR playing an essential role. IMPORTANCE The bacterial pathogen Pseudomonas aeruginosa causes devastating infections in immunocompromised hosts, including chronic lung infections in cystic fibrosis patients. To combat infection, the host’s immune system produces the antimicrobial oxidants hypochlorous acid (HOCl) and hypothiocyanous acid (HOSCN). Little is known about how P. aeruginosa responds to and survives attack from these oxidants. To address this, we carried out two approaches: a mutant screen and transcriptional study. We identified the P. aeruginosa transcriptional regulator, RclR, which responds specifically to HOCl and HOSCN stress and is essential for protection against both oxidants. We uncovered a link between the P. aeruginosa transcriptional response to these oxidants and physiological processes associated with pathogenicity, including antibiotic resistance and the type 3 secretion system.
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16
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Iftikhar A, Asif A, Manzoor A, Azeem M, Sarwar G, Rashid N, Qaisar U. Mutation in pvcABCD operon of Pseudomonas aeruginosa modulates MexEF-OprN efflux system and hence resistance to chloramphenicol and ciprofloxacin. Microb Pathog 2020; 149:104491. [PMID: 32941967 DOI: 10.1016/j.micpath.2020.104491] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 09/05/2020] [Accepted: 09/05/2020] [Indexed: 11/17/2022]
Abstract
Pseudomonas aeruginosa harbors pvcABCD operon that is responsible for the synthesis of paerucumarin. Here we report the involvement of pvcABCD operon in chloramphenicol and ciprofloxacin resistance. P. aeruginosa mutant defective in pvcB (PW4832) was more sensitive to chloramphenicol and ciprofloxacin in comparison with its parent strain (MPAO1). A mutation in pvcA gene in MPAO1 (PW4830) did not alter the sensitivity to either antibiotic. As chloramphenicol and ciprofloxacin are substrates of MexEF-OprN efflux pump, so we decided to investigate the modulation of MexEF-OprN and its transcriptional regulator MexT in PW4832, PW4830 and MPAO1 strains. We isolated and sequenced mexT gene from MPAO1, PW4830 and PW4832. The nucleotide sequence of mexT gene in all three strains was identical. Expression levels of mexEF-oprN, mexT and mexS genes were checked via quantitative real-time RT-PCR. All these genes showed significant repression in mRNA levels in PW4832 as compared to MPAO1. These results indicate that chloramphenicol and ciprofloxacin sensitivity in PW4832 is due to transcriptional repression of mexT and mexEF-oprN genes. Exogenous addition of paerucumarin resumed the expression of mexT and mexEF-oprN genes as well as resistance against chloramphenicol and ciprofloxacin in PW4832 strain. This is a novel finding linking pvcB gene of P. aeruginosa with chloramphenicol and ciprofloxacin resistance and MexEF-OprN pump modulation which needs to be further explored.
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Affiliation(s)
- Anam Iftikhar
- School of Biological Sciences, University of the Punjab, Lahore, Pakistan
| | - Azka Asif
- School of Biological Sciences, University of the Punjab, Lahore, Pakistan
| | - Asma Manzoor
- Institute of Biochemistry and Biotechnology, University of the Punjab, Lahore, Pakistan
| | - Muhammad Azeem
- Botany Department, Government College University, Faisalabad, Pakistan
| | - Ghulam Sarwar
- Cotton Research Station, Ayub Agriculture Research Institute, Faisalabad, Pakistan
| | - Naeem Rashid
- School of Biological Sciences, University of the Punjab, Lahore, Pakistan
| | - Uzma Qaisar
- School of Biological Sciences, University of the Punjab, Lahore, Pakistan.
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17
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Alcalde-Rico M, Olivares-Pacheco J, Halliday N, Cámara M, Martínez JL. The impaired quorum sensing response of Pseudomonas aeruginosa MexAB-OprM efflux pump overexpressing mutants is not due to non-physiological efflux of 3-oxo-C12-HSL. Environ Microbiol 2020; 22:5167-5188. [PMID: 32715566 DOI: 10.1111/1462-2920.15177] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 06/18/2020] [Accepted: 07/24/2020] [Indexed: 11/29/2022]
Abstract
Multidrug (MDR) efflux pumps are ancient and conserved molecular machineries with relevant roles in different aspects of the bacterial physiology, besides antibiotic resistance. In the case of the environmental opportunistic pathogen Pseudomonas aeruginosa, it has been shown that overexpression of different efflux pumps is linked to the impairment of the quorum sensing (QS) response. Nevertheless, the causes of such impairment are different for each analysed efflux pump. Herein, we performed an in-depth analysis of the QS-mediated response of a P. aeruginosa antibiotic resistant mutant that overexpresses MexAB-OprM. Although previous work claimed that this efflux pump extrudes the QS signal 3-oxo-C12-HSL, we show otherwise. Our results evidence that the observed attenuation in the QS response when overexpressing this pump is related to an impaired production of alkyl quinolone QS signals, likely prompted by the reduced availability of one of their precursors, the octanoate. Together with previous studies, this indicates that, although the consequences of overexpressing efflux pumps are similar (impaired QS response), the underlying mechanisms are different. This 'apparent redundancy' of MDR efflux systems can be understood as a P. aeruginosa strategy to keep the robustness of the QS regulatory network and modulate its output in response to different signals.
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Affiliation(s)
- Manuel Alcalde-Rico
- Centro Nacional de Biotecnología, CSIC, Madrid, 28049, Spain.,Grupo de Resistencia Antimicrobiana en Bacterias Patógenas y Ambientales GRABPA, Instituto de Biología, Facultad de Ciencias, Pontificia Universidad Católica de Valparaíso, Valparaiso, 2340025, Chile.,Millennium Nucleus for Collaborative Research on Bacterial Resistance (MICROB-R), Santiago, Chile
| | - Jorge Olivares-Pacheco
- Grupo de Resistencia Antimicrobiana en Bacterias Patógenas y Ambientales GRABPA, Instituto de Biología, Facultad de Ciencias, Pontificia Universidad Católica de Valparaíso, Valparaiso, 2340025, Chile.,Millennium Nucleus for Collaborative Research on Bacterial Resistance (MICROB-R), Santiago, Chile
| | - Nigel Halliday
- National Biofilms Innovation Centre, Nottingham University Biodiscovery Institute, School of Life Sciences, University of Nottingham, Nottingham, UK
| | - Miguel Cámara
- National Biofilms Innovation Centre, Nottingham University Biodiscovery Institute, School of Life Sciences, University of Nottingham, Nottingham, UK
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18
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Shao X, Xie Y, Zhang Y, Liu J, Ding Y, Wu M, Wang X, Deng X. Novel therapeutic strategies for treating Pseudomonas aeruginosa infection. Expert Opin Drug Discov 2020; 15:1403-1423. [PMID: 32880507 DOI: 10.1080/17460441.2020.1803274] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
INTRODUCTION Persistent infections caused by the superbug Pseudomonas aeruginosa and its resistance to multiple antimicrobial agents are huge threats to patients with cystic fibrosis as well as those with compromised immune systems. Multidrug-resistant P. aeruginosa has posed a major challenge to conventional antibiotics and therapeutic approaches, which show limited efficacy and cause serious side effects. The public demand for new antibiotics is enormous; yet, drug development pipelines have started to run dry with limited targets available for inventing new antibacterial drugs. Consequently, it is important to uncover potential therapeutic targets. AREAS COVERED The authors review the current state of drug development strategies that are promising in terms of the development of novel and potent drugs to treat P. aeruginosa infection. EXPERT OPINION The prevention of P. aeruginosa infection is increasingly challenging. Furthermore, targeting key virulence regulators has great potential for developing novel anti-P. aeruginosa drugs. Additional promising strategies include bacteriophage therapy, immunotherapies, and antimicrobial peptides. Additionally, the authors believe that in the coming years, the overall network of molecular regulatory mechanism of P. aeruginosa virulence will be fully elucidated, which will provide more novel and promising drug targets for treating P. aeruginosa infections.
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Affiliation(s)
- Xiaolong Shao
- Department of Biomedical Sciences, City University of Hong Kong , Hong Kong SAR, China
| | - Yingpeng Xie
- Department of Biomedical Sciences, City University of Hong Kong , Hong Kong SAR, China
| | - Yingchao Zhang
- Department of Biomedical Sciences, City University of Hong Kong , Hong Kong SAR, China
| | - Jingui Liu
- Department of Biomedical Sciences, City University of Hong Kong , Hong Kong SAR, China
| | - Yiqing Ding
- Department of Biomedical Sciences, City University of Hong Kong , Hong Kong SAR, China
| | - Min Wu
- Department of Biomedical Sciences, University of North Dakota , Grand Forks, North Dakota, USA
| | - Xin Wang
- Department of Biomedical Sciences, City University of Hong Kong , Hong Kong SAR, China
| | - Xin Deng
- Department of Biomedical Sciences, City University of Hong Kong , Hong Kong SAR, China.,Shenzhen Research Institute, City University of Hong Kong , Shenzhen, China
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19
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Contributions of a LysR Transcriptional Regulator to Listeria monocytogenes Virulence and Identification of Its Regulons. J Bacteriol 2020; 202:JB.00087-20. [PMID: 32179628 DOI: 10.1128/jb.00087-20] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Accepted: 02/20/2020] [Indexed: 12/22/2022] Open
Abstract
The capacity of Listeria monocytogenes to adapt to environmental changes is facilitated by a large number of regulatory proteins encoded by its genome. Among these proteins are the uncharacterized LysR-type transcriptional regulators (LTTRs). LTTRs can work as positive and/or negative transcription regulators at both local and global genetic levels. Previously, our group determined by comparative genome analysis that one member of the LTTRs (NCBI accession no. WP_003734782) was present in pathogenic strains but absent from nonpathogenic strains. The goal of the present study was to assess the importance of this transcription factor in the virulence of L. monocytogenes strain F2365 and to identify its regulons. An L. monocytogenes strain lacking lysR (the F2365ΔlysR strain) displayed significant reductions in cell invasion of and adhesion to Caco-2 cells. In plaque assays, the deletion of lysR resulted in a 42.86% decrease in plaque number and a 13.48% decrease in average plaque size. Furthermore, the deletion of lysR also attenuated the virulence of L. monocytogenes in mice following oral and intraperitoneal inoculation. The analysis of transcriptomics revealed that the transcript levels of 139 genes were upregulated, while 113 genes were downregulated in the F2365ΔlysR strain compared to levels in the wild-type bacteria. lysR-repressed genes included ABC transporters, important for starch and sucrose metabolism as well as glycerolipid metabolism, flagellar assembly, quorum sensing, and glycolysis/gluconeogenesis. Conversely, lysR activated the expression of genes related to fructose and mannose metabolism, cationic antimicrobial peptide (CAMP) resistance, and beta-lactam resistance. These data suggested that lysR contributed to L. monocytogenes virulence by broad impact on multiple pathways of gene expression.IMPORTANCE Listeria monocytogenes is the causative agent of listeriosis, an infectious and fatal disease of animals and humans. In this study, we have shown that lysR contributes to Listeria pathogenesis and replication in cell lines. We also highlight the importance of lysR in regulating the transcription of genes involved in different pathways that might be essential for the growth and persistence of L. monocytogenes in the host or under nutrient limitation. Better understanding L. monocytogenes pathogenesis and the role of various virulence factors is necessary for further development of prevention and control strategies.
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20
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Kim S, Kim SH, Ahn J, Jo I, Lee ZW, Choi SH, Ha NC. Crystal Structure of the Regulatory Domain of MexT, a Transcriptional Activator of the MexEFOprN Efflux Pump in Pseudomonas aeruginosa. Mol Cells 2019; 42:850-857. [PMID: 31722511 PMCID: PMC6939650 DOI: 10.14348/molcells.2019.0168] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 09/06/2019] [Accepted: 10/07/2019] [Indexed: 12/02/2022] Open
Abstract
The Gram-negative opportunistic pathogen, Pseudomonas aeruginosa , has multiple multidrug efflux pumps. MexT, a LysR-type transcriptional regulator, functions as a transcriptional activator of the MexEF-OprN efflux system. MexT consists of an N-terminal DNA-binding domain and a C-terminal regulatory domain (RD). Little is known regarding MexT ligands and its mechanism of activation. We elucidated the crystal structure of the MexT RD at 2.0 Å resolution. The structure comprised two protomer chains in a dimeric arrangement. MexT possessed an arginine-rich region and a hydrophobic patch lined by a variable loop, both of which are putative ligand-binding sites. The three-dimensional structure of MexT provided clues to the interacting ligand structure. A DNase I footprinting assay of full-length MexT identified two MexT-binding sequence in the mexEF oprN promoter. Our findings enhance the understanding of the regulation of MexT-dependent activation of efflux pumps.
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Affiliation(s)
- Suhyeon Kim
- Department of Agricultural Biotechnology, Center for Food Safety and Toxicology, Center for Food and Bioconvergence, and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul 08826,
Korea
| | - Songhee H. Kim
- Institute of Molecular Biology and Genetics, Seoul National University, Seoul 08826,
Korea
| | - Jinsook Ahn
- Department of Agricultural Biotechnology, Center for Food Safety and Toxicology, Center for Food and Bioconvergence, and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul 08826,
Korea
| | - Inseong Jo
- Department of Agricultural Biotechnology, Center for Food Safety and Toxicology, Center for Food and Bioconvergence, and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul 08826,
Korea
| | - Zee-Won Lee
- Department of Agricultural Biotechnology, Center for Food Safety and Toxicology, Center for Food and Bioconvergence, and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul 08826,
Korea
| | - Sang Ho Choi
- Department of Agricultural Biotechnology, Center for Food Safety and Toxicology, Center for Food and Bioconvergence, and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul 08826,
Korea
| | - Nam-Chul Ha
- Department of Agricultural Biotechnology, Center for Food Safety and Toxicology, Center for Food and Bioconvergence, and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul 08826,
Korea
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21
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LoVullo ED, Schweizer HP. Pseudomonas aeruginosa mexT is an indicator of PAO1 strain integrity. J Med Microbiol 2019; 69:139-145. [PMID: 31859619 DOI: 10.1099/jmm.0.001128] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Laboratory research with Pseudomonas aeruginosa commonly involves the prototype strain PAO1. There is continued concern that PAO1 sublines maintained and propagated in the same laboratory or different laboratories exhibit genetic and phenotypic variability that may affect the reproducibility and validity of research. Whole-genome sequencing and other research identified the mexT locus as a mutational hotspot, but the explication of the diverse mutations present in the various sublines and consequences remained rather cursory. Here we present evidence that MexT sequence diversity is a predictor of PAO1 lineage integrity and define the protein's prototype sequence.
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Affiliation(s)
- Eric D LoVullo
- Department of Molecular Genetics and Microbiology, College of Medicine, Emerging Pathogens Institute, 2055 Mowry Road, Gainesville, FL 32610, USA
| | - Herbert P Schweizer
- Department of Molecular Genetics and Microbiology, College of Medicine, Emerging Pathogens Institute, 2055 Mowry Road, Gainesville, FL 32610, USA
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22
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Xu Z, Li M, Li Y, Cao H, Miao L, Xu Z, Higuchi Y, Yamasaki S, Nishino K, Woo PC, Xiang H, Yan A. Native CRISPR-Cas-Mediated Genome Editing Enables Dissecting and Sensitizing Clinical Multidrug-Resistant P. aeruginosa. Cell Rep 2019; 29:1707-1717.e3. [DOI: 10.1016/j.celrep.2019.10.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2019] [Revised: 09/09/2019] [Accepted: 09/30/2019] [Indexed: 02/06/2023] Open
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23
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Hill IT, Tallo T, Dorman MJ, Dove SL. Loss of RNA Chaperone Hfq Unveils a Toxic Pathway in Pseudomonas aeruginosa. J Bacteriol 2019; 201:e00232-19. [PMID: 31358608 PMCID: PMC6755729 DOI: 10.1128/jb.00232-19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 07/22/2019] [Indexed: 12/17/2022] Open
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.
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Affiliation(s)
- Ian T Hill
- Division of Infectious Diseases, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Thomas Tallo
- Division of Infectious Diseases, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Matthew J Dorman
- Division of Infectious Diseases, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Simon L Dove
- Division of Infectious Diseases, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
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24
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Andrews LD, Kane TR, Dozzo P, Haglund CM, Hilderbrandt DJ, Linsell MS, Machajewski T, McEnroe G, Serio AW, Wlasichuk KB, Neau DB, Pakhomova S, Waldrop GL, Sharp M, Pogliano J, Cirz RT, Cohen F. Optimization and Mechanistic Characterization of Pyridopyrimidine Inhibitors of Bacterial Biotin Carboxylase. J Med Chem 2019; 62:7489-7505. [PMID: 31306011 DOI: 10.1021/acs.jmedchem.9b00625] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
A major challenge for new antibiotic discovery is predicting the physicochemical properties that enable small molecules to permeate Gram-negative bacterial membranes. We have applied physicochemical lessons from previous work to redesign and improve the antibacterial potency of pyridopyrimidine inhibitors of biotin carboxylase (BC) by up to 64-fold and 16-fold against Escherichia coli and Pseudomonas aeruginosa, respectively. Antibacterial and enzyme potency assessments in the presence of an outer membrane-permeabilizing agent or in efflux-compromised strains indicate that penetration and efflux properties of many redesigned BC inhibitors could be improved to various extents. Spontaneous resistance to the improved pyridopyrimidine inhibitors in P. aeruginosa occurs at very low frequencies between 10-8 and 10-9. However, resistant isolates had alarmingly high minimum inhibitory concentration shifts (16- to >128-fold) compared to the parent strain. Whole-genome sequencing of resistant isolates revealed that either BC target mutations or efflux pump overexpression can lead to the development of high-level resistance.
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Affiliation(s)
- Logan D Andrews
- Former employee of Achaogen Inc. , 1 Tower Place, Suite 400 , South San Francisco , California 94080 , United States
| | - Timothy R Kane
- Former employee of Achaogen Inc. , 1 Tower Place, Suite 400 , South San Francisco , California 94080 , United States
| | - Paola Dozzo
- Former employee of Achaogen Inc. , 1 Tower Place, Suite 400 , South San Francisco , California 94080 , United States
| | - Cat M Haglund
- Former employee of Achaogen Inc. , 1 Tower Place, Suite 400 , South San Francisco , California 94080 , United States
| | - Darin J Hilderbrandt
- Former employee of Achaogen Inc. , 1 Tower Place, Suite 400 , South San Francisco , California 94080 , United States
| | - Martin S Linsell
- Former employee of Achaogen Inc. , 1 Tower Place, Suite 400 , South San Francisco , California 94080 , United States
| | - Timothy Machajewski
- Former employee of Achaogen Inc. , 1 Tower Place, Suite 400 , South San Francisco , California 94080 , United States
| | - Glen McEnroe
- Former employee of Achaogen Inc. , 1 Tower Place, Suite 400 , South San Francisco , California 94080 , United States
| | - Alisa W Serio
- Former employee of Achaogen Inc. , 1 Tower Place, Suite 400 , South San Francisco , California 94080 , United States
| | - Kenneth B Wlasichuk
- Former employee of Achaogen Inc. , 1 Tower Place, Suite 400 , South San Francisco , California 94080 , United States
| | - David B Neau
- Northeastern Collaborative Access Team , Argonne National Laboratory , Argonne , Illinois 60439 , United States
| | - Svetlana Pakhomova
- Department of Biological Sciences , Louisiana State University , Baton Rouge , Louisiana 70803 , United States
| | - Grover L Waldrop
- Department of Biological Sciences , Louisiana State University , Baton Rouge , Louisiana 70803 , United States
| | - Marc Sharp
- Linnaeus Bioscience Inc. , 3210 Merryfield Row , San Diego , California 92121 , United States
| | - Joe Pogliano
- Linnaeus Bioscience Inc. , 3210 Merryfield Row , San Diego , California 92121 , United States.,University of California, San Diego , 9500 Gilman Drive , La Jolla, San Diego , California 92093 , United States
| | - Ryan T Cirz
- Former employee of Achaogen Inc. , 1 Tower Place, Suite 400 , South San Francisco , California 94080 , United States
| | - Frederick Cohen
- Former employee of Achaogen Inc. , 1 Tower Place, Suite 400 , South San Francisco , California 94080 , United States
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25
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An integrated genomic regulatory network of virulence-related transcriptional factors in Pseudomonas aeruginosa. Nat Commun 2019; 10:2931. [PMID: 31270321 PMCID: PMC6610081 DOI: 10.1038/s41467-019-10778-w] [Citation(s) in RCA: 92] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Accepted: 05/30/2019] [Indexed: 01/12/2023] Open
Abstract
The virulence of Pseudomonas aeruginosa, a Gram-negative opportunistic pathogen, is regulated by many transcriptional factors (TFs) that control the expression of quorum sensing and protein secretion systems. Here, we report a genome-wide, network-based approach to dissect the crosstalk between 20 key virulence-related TFs. Using chromatin immunoprecipitation coupled with high-throughput sequencing (ChIP-seq), as well as RNA-seq, we identify 1200 TF-bound genes and 4775 differentially expressed genes. We experimentally validate 347 of these genes as functional target genes, and describe the regulatory relationships of the 20 TFs with their targets in a network that we call ‘Pseudomonas aeruginosa genomic regulatory network’ (PAGnet). Analysis of the network led to the identification of novel functions for two TFs (ExsA and GacA) in quorum sensing and nitrogen metabolism. Furthermore, we present an online platform and R package based on PAGnet to facilitate updating and user-customised analyses. The virulence of Pseudomonas aeruginosa is regulated by many transcriptional factors (TFs). Here, the authors study the crosstalk between 20 key virulence-related TFs, validate 347 functional target genes, and describe the regulatory relationships of the 20 TFs with their targets in a network that is available as an online platform.
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26
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Abstract
The bacterial pathogen Pseudomonas aeruginosa activates expression of many virulence genes in a cell density-dependent manner by using an intricate quorum-sensing (QS) network. QS in P. aeruginosa involves two acyl-homoserine-lactone circuits, LasI-LasR and RhlI-RhlR. LasI-LasR is required to activate many genes including those coding for RhlI-RhlR. P. aeruginosa causes chronic infections in the lungs of people with cystic fibrosis (CF). In these infections, LasR mutants are common, but rhlR-rhlI expression has escaped LasR regulation in many CF isolates. To better understand the evolutionary trajectory of P. aeruginosa QS in chronic infections, we grew LasR mutants of the well-studied P. aeruginosa strain, PAO1, in conditions that recapitulate an environment where QS signal synthesis by other bacteria might still occur. When QS is required for growth, addition of the RhlI product butyryl-homoserine lactone (C4-HSL), or bacteria that produce C4-HSL, to LasR mutants results in the rapid emergence of a population with a LasR-independent RhlI-RhlR QS system. These evolved populations exhibit subsequent growth without added C4-HSL. The variants that emerge have mutations in mexT, which codes for a transcription factor that controls expression of multiple genes. LasR-MexT mutants have a competitive advantage over both the parent LasR mutant and a LasR-MexT-RhlR mutant. Our findings suggest a plausible evolutionary trajectory for QS in P. aeruginosa CF infections where LasR mutants arise during infection, but because these mutants are surrounded by C4-HSL-producing P. aeruginosa, variants rewired to have a LasR-independent RhlIR system quickly emerge.
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27
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Alcalde-Rico M, Olivares-Pacheco J, Alvarez-Ortega C, Cámara M, Martínez JL. Role of the Multidrug Resistance Efflux Pump MexCD-OprJ in the Pseudomonas aeruginosa Quorum Sensing Response. Front Microbiol 2018; 9:2752. [PMID: 30532741 PMCID: PMC6266676 DOI: 10.3389/fmicb.2018.02752] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 10/26/2018] [Indexed: 11/15/2022] Open
Abstract
Multidrug efflux pumps constitute a category of antibiotic resistance determinants that are a part of the core bacterial genomes. Given their conservation, it is conceivable that they present functions beyond the extrusion of antibiotics currently used for therapy. Pseudomonas aeruginosa stands as a relevant respiratory pathogen, with a high prevalence at hospitals and in cystic fibrosis patients. Part of its success relies on its low susceptibility to antibiotics and on the production of virulence factors, whose expression is regulated in several cases by quorum sensing (QS). We found that overexpression of the MexCD-OprJ multidrug efflux pump shuts down the P. aeruginosa QS response. Our results support that MexCD-OprJ extrudes kynurenine, a precursor of the alkyl-quinolone signal (AQS) molecules. Anthranilate and octanoate, also AQS precursors, do not seem to be extruded by MexCD-OprJ. Kynurenine extrusion is not sufficient to reduce the QS response in a mutant overexpressing this efflux pump. Impaired QS response is mainly due to the extrusion of 4-hydroxy-2-heptylquinoline (HHQ), the precursor of the Pseudomonas Quinolone Signal (PQS), leading to low PQS intracellular levels and reduced production of QS signal molecules. As the consequence, the expression of QS-regulated genes is impaired and the production of QS-regulated virulence factors strongly decreases in a MexCD-OprN P. aeruginosa overexpressing mutant. Previous work showed that MexEF-OprJ, another P. aeruginosa efflux pump, is also able of extruding kynurenine and HHQ. However, opposite to our findings, the QS defect in a MexEF-OprN overproducer is due to kynurenine extrusion. These results indicate that, although efflux pumps can share some substrates, the affinity for each of them can be different. Although the QS response is triggered by population density, information on additional elements able of modulating such response is still scarce. This is particularly important in the case of P. aeruginosa lung chronic infections, a situation in which QS-defective mutants are accumulated. If MexCD-OprJ overexpression alleviates the cost associated to triggering the QS response when un-needed, it could be possible that MexCD-OprJ antibiotic resistant overproducer strains might be selected even in the absence of antibiotic selective pressure, acting as antibiotic resistant cheaters in heterogeneous P. aeruginosa populations.
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Affiliation(s)
- Manuel Alcalde-Rico
- Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Jorge Olivares-Pacheco
- Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Carolina Alvarez-Ortega
- Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Miguel Cámara
- Centre for Biomolecular Sciences, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - José Luis Martínez
- Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, Madrid, Spain
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28
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Oshri RD, Zrihen KS, Shner I, Omer Bendori S, Eldar A. Selection for increased quorum-sensing cooperation in Pseudomonas aeruginosa through the shut-down of a drug resistance pump. ISME JOURNAL 2018; 12:2458-2469. [PMID: 29925881 PMCID: PMC6154968 DOI: 10.1038/s41396-018-0205-y] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 05/10/2018] [Accepted: 05/15/2018] [Indexed: 01/24/2023]
Abstract
The opportunistic pathogen Pseudomonas aeruginosa employs a hierarchical quorum-sensing network to regulate virulence factor production that cooperatively benefit the population at a cost to the individual. It has been argued that the evolution of a cooperative mutant in a quorum sensing-suppressed population would be hampered through its exploitation by neighboring non-mutant cells. It remains unclear whether mechanisms which overcome this exploitation exist. Here we investigate the regain of quorum-sensing cooperation by evolving a mutant of the lasR master quorum-sensing regulator. The mutant regained partial cooperative growth through null mutations in mexT, which codes for an activator of the MexEF-OprN multidrug-resistant pump. We find that these mutations enhance cooperative growth in both the lasR mutant and wild-type backgrounds through the activation of the RhlIR system. We show that the regain of cooperation in mexT mutants is mediated by the reduction in MexEF-OprN activity, whereas an additional source of private benefit is mostly mexEF-oprN-independent. Finally, we show that addition of antibiotics for which resistance is mediated by MexEF-OprN prevents the selection of increased cooperation at sub-MIC concentrations. MexT, therefore, not only links private and public goods, but also exposes conflicts between selection for antibiotic resistance and enhanced cooperation.
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Affiliation(s)
- Ron D Oshri
- School of Molecular Cell Biology and Biotechnology, Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel
| | - Keren S Zrihen
- School of Molecular Cell Biology and Biotechnology, Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel
| | - Itzhak Shner
- School of Molecular Cell Biology and Biotechnology, Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel
| | - Shira Omer Bendori
- School of Molecular Cell Biology and Biotechnology, Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel
| | - Avigdor Eldar
- School of Molecular Cell Biology and Biotechnology, Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel.
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29
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Vasileva D, Suzuki-Minakuchi C, Kosono S, Yoshida M, Okada K, Nojiri H. Proteome and acylome analyses of the functional interaction network between the carbazole-degradative plasmid pCAR1 and host Pseudomonas putida KT2440. ENVIRONMENTAL MICROBIOLOGY REPORTS 2018; 10:299-309. [PMID: 29573367 DOI: 10.1111/1758-2229.12639] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Revised: 03/08/2018] [Accepted: 03/10/2018] [Indexed: 06/08/2023]
Abstract
Understanding the interplay between a plasmid and its host system is a bottleneck towards prediction of the fate of plasmid-harbouring strains in the natural environments. Here, we studied the impact of the conjugative plasmid pCAR1, involved in carbazole degradation, on the proteome of Pseudomonas putida KT2440 using SILAC method. Furthermore, we investigated two acyl lysine modifications (acetylation and succinylation) that respond to the metabolic status of the cell and are implicated in regulation of various cellular processes. The total proteome analysis revealed that the abundance of key proteins involved in metabolism, signal transduction and motility was affected by pCAR1 carriage. In total, we identified 1359 unique acetylation sites on 637 proteins and 567 unique succinylation sites on 259 proteins. Changes in the acylation status of proteins involved in metabolism and translation by pCAR1 carriage were detected. Remarkably, acylation was identified on proteins involved in important plasmid functions, including partitioning and carbazole degradation, and on nucleoid-associated proteins that play a key role in the functional interaction with the chromosome. This study provides a novel insight on the functional consequences of plasmid carriage and improves our understanding of the plasmid-host cross-talk.
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Affiliation(s)
- Delyana Vasileva
- Biotechnology Research Center, The University of Tokyo, Tokyo, Japan
| | | | - Saori Kosono
- Biotechnology Research Center, The University of Tokyo, Tokyo, Japan
- RIKEN Center for Sustainable Resource Science Wako, Saitama, Japan
| | - Minoru Yoshida
- RIKEN Center for Sustainable Resource Science Wako, Saitama, Japan
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Kazunori Okada
- Biotechnology Research Center, The University of Tokyo, Tokyo, Japan
| | - Hideaki Nojiri
- Biotechnology Research Center, The University of Tokyo, Tokyo, Japan
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30
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Duong LT, Schwarz S, Gross H, Breitbach K, Hochgräfe F, Mostertz J, Eske-Pogodda K, Wagner GE, Steinmetz I, Kohler C. GvmR - A Novel LysR-Type Transcriptional Regulator Involved in Virulence and Primary and Secondary Metabolism of Burkholderia pseudomallei. Front Microbiol 2018; 9:935. [PMID: 29867844 PMCID: PMC5964159 DOI: 10.3389/fmicb.2018.00935] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 04/23/2018] [Indexed: 01/22/2023] Open
Abstract
Burkholderia pseudomallei is a soil-dwelling bacterium able to survive not only under adverse environmental conditions, but also within various hosts which can lead to the disease melioidosis. The capability of B. pseudomallei to adapt to environmental changes is facilitated by the large number of regulatory proteins encoded by its genome. Among them are more than 60 uncharacterized LysR-type transcriptional regulators (LTTRs). Here we analyzed a B. pseudomallei mutant harboring a transposon in the gene BPSL0117 annotated as a LTTR, which we named gvmR (globally acting virulence and metabolism regulator). The gvmR mutant displayed a growth defect in minimal medium and macrophages in comparison with the wild type. Moreover, disruption of gvmR rendered B. pseudomallei avirulent in mice indicating a critical role of GvmR in infection. These defects of the mutant were rescued by ectopic expression of gvmR. To identify genes whose expression is modulated by GvmR, global transcriptome analysis of the B. pseudomallei wild type and gvmR mutant was performed using whole genome tiling microarrays. Transcript levels of 190 genes were upregulated and 141 genes were downregulated in the gvmR mutant relative to the wild type. Among the most downregulated genes in the gvmR mutant were important virulence factor genes (T3SS3, T6SS1, and T6SS2), which could explain the virulence defect of the gvmR mutant. In addition, expression of genes related to amino acid synthesis, glyoxylate shunt, iron-sulfur cluster assembly, and syrbactin metabolism (secondary metabolite) was decreased in the mutant. On the other hand, inactivation of GvmR increased expression of genes involved in pyruvate metabolism, ATP synthesis, malleobactin, and porin genes. Quantitative real-time PCR verified the differential expression of 27 selected genes. In summary, our data show that GvmR acts as an activating and repressing global regulator that is required to coordinate expression of a diverse set of metabolic and virulence genes essential for the survival in the animal host and under nutrient limitation.
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Affiliation(s)
- Linh Tuan Duong
- Friedrich Loeffler Institute of Medical Microbiology, University Medicine Greifswald, Greifswald, Germany
| | - Sandra Schwarz
- Interfaculty Institute of Microbiology and Infection Medicine Tübingen, University of Tübingen, Tübingen, Germany
| | - Harald Gross
- Department of Pharmaceutical Biology, Pharmaceutical Institute, Eberhard Karls University of Tübingen, Tübingen, Germany.,German Centre for Infection Research, Partner Site Tübingen, Tübingen, Germany
| | - Katrin Breitbach
- Friedrich Loeffler Institute of Medical Microbiology, University Medicine Greifswald, Greifswald, Germany
| | - Falko Hochgräfe
- Competence Center Functional Genomics, Junior Research Group Pathoproteomics, University of Greifswald, Greifswald, Germany
| | - Jörg Mostertz
- Competence Center Functional Genomics, Junior Research Group Pathoproteomics, University of Greifswald, Greifswald, Germany
| | - Kristin Eske-Pogodda
- Friedrich Loeffler Institute of Medical Microbiology, University Medicine Greifswald, Greifswald, Germany
| | - Gabriel E Wagner
- Institute of Hygiene, Microbiology and Environmental Medicine, Medical University of Graz, Graz, Austria
| | - Ivo Steinmetz
- Friedrich Loeffler Institute of Medical Microbiology, University Medicine Greifswald, Greifswald, Germany.,Institute of Hygiene, Microbiology and Environmental Medicine, Medical University of Graz, Graz, Austria
| | - Christian Kohler
- Friedrich Loeffler Institute of Medical Microbiology, University Medicine Greifswald, Greifswald, Germany
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31
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Constitutive Activation of MexT by Amino Acid Substitutions Results in MexEF-OprN Overproduction in Clinical Isolates of Pseudomonas aeruginosa. Antimicrob Agents Chemother 2018. [PMID: 29530852 DOI: 10.1128/aac.02445-17] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
When overproduced, the multidrug efflux system MexEF-OprN increases the resistance of Pseudomonas aeruginosa to fluoroquinolones, chloramphenicol, and trimethoprim. In this work, we demonstrate that gain-of-function mutations in the regulatory gene mexT result in oligomerization of the LysR regulator MexT, constitutive upregulation of the efflux pump, and increased resistance in clinical isolates.
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32
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The Microbial Endocrinology of Pseudomonas aeruginosa: Inflammatory and Immune Perspectives. Arch Immunol Ther Exp (Warsz) 2018. [PMID: 29541797 DOI: 10.1007/s00005-018-0510-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Pseudomonas aeruginosa is a major pathogen responsible for both acute and chronic infection. Known as a colonising pathogen of the cystic fibrosis (CF) lung, it is implicated in other settings such as bronchiectasis. It has the ability to cause acute disseminated or localised infection particularly in the immunocompromised. Human hormones have been highlighted as potential regulators of bacterial virulence through crosstalk between analogous "quorum sensing" (QS) systems present in the bacteria that respond to mammalian hormones. Pseudomonas aeruginosa is known to utilise interconnected QS systems to coordinate its virulence and evade various aspects of the host immune system activated in response to infection. Several human hormones demonstrate an influence on P. aeruginosa growth and virulence. This inter-kingdom signalling, termed "microbial endocrinology" has important implications for host-microbe interaction during infection and, potentially opens up novel avenues for therapeutic intervention. This phenomenon, supported by the existence of sexual dichotomies in both microbial infection and chronic lung diseases such as CF is potentially explained by sex hormones and their influence on the infective process. This review summarises our current understanding of the microbial endocrinology of P. aeruginosa, including its endogenous QS systems and their intersection with human endocrinology, pathogenesis of infection and the host immune system.
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33
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Tan J, Huyck M, Hu D, Zelaya RA, Hogan DA, Greene CS. ADAGE signature analysis: differential expression analysis with data-defined gene sets. BMC Bioinformatics 2017; 18:512. [PMID: 29166858 PMCID: PMC5700673 DOI: 10.1186/s12859-017-1905-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Accepted: 11/01/2017] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Gene set enrichment analysis and overrepresentation analyses are commonly used methods to determine the biological processes affected by a differential expression experiment. This approach requires biologically relevant gene sets, which are currently curated manually, limiting their availability and accuracy in many organisms without extensively curated resources. New feature learning approaches can now be paired with existing data collections to directly extract functional gene sets from big data. RESULTS Here we introduce a method to identify perturbed processes. In contrast with methods that use curated gene sets, this approach uses signatures extracted from public expression data. We first extract expression signatures from public data using ADAGE, a neural network-based feature extraction approach. We next identify signatures that are differentially active under a given treatment. Our results demonstrate that these signatures represent biological processes that are perturbed by the experiment. Because these signatures are directly learned from data without supervision, they can identify uncurated or novel biological processes. We implemented ADAGE signature analysis for the bacterial pathogen Pseudomonas aeruginosa. For the convenience of different user groups, we implemented both an R package (ADAGEpath) and a web server ( http://adage.greenelab.com ) to run these analyses. Both are open-source to allow easy expansion to other organisms or signature generation methods. We applied ADAGE signature analysis to an example dataset in which wild-type and ∆anr mutant cells were grown as biofilms on the Cystic Fibrosis genotype bronchial epithelial cells. We mapped active signatures in the dataset to KEGG pathways and compared with pathways identified using GSEA. The two approaches generally return consistent results; however, ADAGE signature analysis also identified a signature that revealed the molecularly supported link between the MexT regulon and Anr. CONCLUSIONS We designed ADAGE signature analysis to perform gene set analysis using data-defined functional gene signatures. This approach addresses an important gap for biologists studying non-traditional model organisms and those without extensive curated resources available. We built both an R package and web server to provide ADAGE signature analysis to the community.
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Affiliation(s)
- Jie Tan
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, NH, 03755, USA
| | - Matthew Huyck
- Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, PA, 19104, USA.,Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, NH, 03755, USA
| | - Dongbo Hu
- Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - René A Zelaya
- Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Deborah A Hogan
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, NH, 03755, USA
| | - Casey S Greene
- Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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Metabolic Compensation of Fitness Costs Is a General Outcome for Antibiotic-Resistant Pseudomonas aeruginosa Mutants Overexpressing Efflux Pumps. mBio 2017; 8:mBio.00500-17. [PMID: 28743808 PMCID: PMC5527304 DOI: 10.1128/mbio.00500-17] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
It is generally assumed that the acquisition of antibiotic resistance is associated with a fitness cost. We have shown that overexpression of the MexEF-OprN efflux pump does not decrease the fitness of a resistant Pseudomonas aeruginosa strain compared to its wild-type counterpart. This lack of fitness cost was associated with a metabolic rewiring that includes increased expression of the anaerobic nitrate respiratory chain when cells are growing under fully aerobic conditions. It was not clear whether this metabolic compensation was exclusive to strains overexpressing MexEF-OprN or if it extended to other resistant strains that overexpress similar systems. To answer this question, we studied a set of P. aeruginosa mutants that independently overexpress the MexAB-OprM, MexCD-OprJ, or MexXY efflux pumps. We observed increased expression of the anaerobic nitrate respiratory chain in all cases, with a concomitant increase in NO3 consumption and NO production. These efflux pumps are proton/substrate antiporters, and their overexpression may lead to intracellular H+ accumulation, which may in turn offset the pH homeostasis. Indeed, all studied mutants showed a decrease in intracellular pH under anaerobic conditions. The fastest way to eliminate the excess of protons is by increasing oxygen consumption, a feature also displayed by all analyzed mutants. Taken together, our results support metabolic rewiring as a general mechanism to avoid the fitness costs derived from overexpression of P. aeruginosa multidrug efflux pumps. The development of drugs that block this metabolic “reaccommodation” might help in reducing the persistence and spread of antibiotic resistance elements among bacterial populations. It is widely accepted that the acquisition of resistance confers a fitness cost in such a way that in the absence of antibiotics, resistant populations will be outcompeted by susceptible ones. Based on this assumption, antibiotic cycling regimes have been proposed in the belief that they will reduce the persistence and spread of resistance among bacterial pathogens. Unfortunately, trials testing this possibility have frequently failed, indicating that resistant microorganisms are not always outcompeted by susceptible ones. Indeed, some mutations do not result in a fitness cost, and in case they do, the cost may be compensated for by a secondary mutation. Here we describe an alternative nonmutational mechanism for compensating for fitness costs, which consists of the metabolic rewiring of resistant mutants. Deciphering the mechanisms involved in the compensation of fitness costs of antibiotic-resistant mutants may help in the development of drugs that will reduce the persistence of resistance by increasing said costs.
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Toxic Electrophiles Induce Expression of the Multidrug Efflux Pump MexEF-OprN in Pseudomonas aeruginosa through a Novel Transcriptional Regulator, CmrA. Antimicrob Agents Chemother 2017; 61:AAC.00585-17. [PMID: 28507116 DOI: 10.1128/aac.00585-17] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Accepted: 05/11/2017] [Indexed: 11/20/2022] Open
Abstract
The multidrug efflux system MexEF-OprN is produced at low levels in wild-type strains of Pseudomonas aeruginosa However, in so-called nfxC mutants, mutational alteration of the gene mexS results in constitutive overexpression of the pump, along with increased resistance of the bacterium to chloramphenicol, fluoroquinolones, and trimethoprim. In this study, analysis of in vitro-selected chloramphenicol-resistant clones of strain PA14 led to the identification of a new class of MexEF-OprN-overproducing mutants (called nfxC2) exhibiting alterations in an as-yet-uncharacterized gene, PA14_38040 (homolog of PA2047 in strain PAO1). This gene is predicted to encode an AraC-like transcriptional regulator and was called cmrA (for chloramphenicol resistance activator). In nfxC2 mutants, the mutated CmrA increases its proper gene expression and upregulates the operon mexEF-oprN through MexS and MexT, resulting in a multidrug resistance phenotype without significant loss in bacterial virulence. Transcriptomic experiments demonstrated that CmrA positively regulates a small set of 11 genes, including PA14_38020 (homolog of PA2048), which is required for the MexS/T-dependent activation of mexEF-oprN PA2048 codes for a protein sharing conserved domains with the quinol monooxygenase YgiN from Escherichia coli Interestingly, exposure of strain PA14 to toxic electrophilic molecules (glyoxal, methylglyoxal, and cinnamaldehyde) strongly activates the CmrA pathway and upregulates MexEF-OprN and, thus, increases the resistance of P. aeruginosa to the pump substrates. A picture emerges in which MexEF-OprN is central in the response of the pathogen to stresses affecting intracellular redox homeostasis.
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Fitness costs associated with the acquisition of antibiotic resistance. Essays Biochem 2017; 61:37-48. [PMID: 28258228 DOI: 10.1042/ebc20160057] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 12/20/2016] [Accepted: 01/03/2017] [Indexed: 01/09/2023]
Abstract
Acquisition of antibiotic resistance is a relevant problem for human health. The selection and spread of antibiotic-resistant organisms not only compromise the treatment of infectious diseases, but also the implementation of different therapeutic procedures as organ transplantation, advanced surgery or chemotherapy, all of which require proficient methods for avoiding infections. It has been generally accepted that the acquisition of antibiotic resistance will produce a general metabolic burden: in the absence of selection, the resistant organisms would be outcompeted by the susceptible ones. If that was always true, discontinuation of antibiotic use would render the disappearance of resistant microorganisms. However, several studies have shown that, once resistance emerges, the recovery of a fully susceptible population even in the absence of antibiotics is not easy. In the present study, we review updated information on the effect of the acquisition of antibiotic resistance in bacterial physiology as well as on the mechanisms that allow the compensation of the fitness costs associated with the acquisition of resistance.
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Sidorenko J, Jatsenko T, Kivisaar M. Ongoing evolution of Pseudomonas aeruginosa PAO1 sublines complicates studies of DNA damage repair and tolerance. Mutat Res 2017; 797-799:26-37. [PMID: 28340408 DOI: 10.1016/j.mrfmmm.2017.03.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 12/23/2016] [Accepted: 03/07/2017] [Indexed: 06/06/2023]
Abstract
Sublines of the major P. aeruginosa reference strain PAO1 are derivatives of the original PAO1 isolate, which are maintained in laboratories worldwide. These sublines display substantial genomic and phenotypic variation due to ongoing microevolution. Here, we examined four sublines, MPAO1, PAO1-L, PAO1-DSM and PAO1-UT, originated from different laboratories, and six DNA polymerase-deficient mutants from the P. aeruginosa MPAO1 transposon library for their employment in elucidation of DNA damage repair and tolerance mechanisms in P. aeruginosa. We found that PAO1 subline PAO1-UT carries a large deletion encompassing the DNA damage inducible imuA-imuB-imuC cassette (PA0669-PA0671), which is implied in mutagenesis in several species. Furthermore, the genetic changes leading to variation in the functionality of the MexEF-OprN efflux system contributed largely to the phenotypic discordance between P. aeruginosa PAO1 sublines. Specifically, we identified multiple mutations in the mexT gene, which encodes a transcriptional regulator of the mexEF-oprN genes, mutations in the mexF, and complete absence of these genes. Of the four tested sublines, MPAO1 was the only subline with the functional MexEF-OprN multidrug efflux system. Active efflux through MexEF-OprN rendered MPAO1 highly resistant to chloramphenicol and ciprofloxacin. Moreover, the functions of specialized DNA polymerase IV and nucleotide excision repair (NER) in 4-NQO-induced DNA damage tolerance appeared to be masked in MPAO1, while were easily detectable in other sublines. Finally, the frequencies of spontaneous and MMS-induced Rifr mutations were also significantly lower in MPAO1 in comparison to the PAO1 sublines with impaired MexEF-OprN efflux system. The MexEF-OprN-attributed differences were also observed between MPAO1 and MPAO1-derived transposon mutants from the two-allele transposon mutant collection. Thus, the accumulating mutations and discordant phenotypes of the PAO1 derivatives challenge the reproducibility and comparability of the results obtained with different PAO1 sublines and also limit the usage of the MPAO1 transposon library in DNA damage tolerance and mutagenesis studies.
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Affiliation(s)
- Julia Sidorenko
- Department of Genetics, Institute of Molecular and Cell Biology, University of Tartu, 23 Riia Street, 51010, Tartu, Estonia.
| | - Tatjana Jatsenko
- Department of Genetics, Institute of Molecular and Cell Biology, University of Tartu, 23 Riia Street, 51010, Tartu, Estonia
| | - Maia Kivisaar
- Department of Genetics, Institute of Molecular and Cell Biology, University of Tartu, 23 Riia Street, 51010, Tartu, Estonia.
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Tian ZX, Yi XX, Cho A, O’Gara F, Wang YP. CpxR Activates MexAB-OprM Efflux Pump Expression and Enhances Antibiotic Resistance in Both Laboratory and Clinical nalB-Type Isolates of Pseudomonas aeruginosa. PLoS Pathog 2016; 12:e1005932. [PMID: 27736975 PMCID: PMC5063474 DOI: 10.1371/journal.ppat.1005932] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 09/13/2016] [Indexed: 12/30/2022] Open
Abstract
Resistance-Nodulation-Division (RND) efflux pumps are responsible for multidrug resistance in Pseudomonas aeruginosa. In this study, we demonstrate that CpxR, previously identified as a regulator of the cell envelope stress response in Escherichia coli, is directly involved in activation of expression of RND efflux pump MexAB-OprM in P. aeruginosa. A conserved CpxR binding site was identified upstream of the mexA promoter in all genome-sequenced P. aeruginosa strains. CpxR is required to enhance mexAB-oprM expression and drug resistance, in the absence of repressor MexR, in P. aeruginosa strains PA14. As defective mexR is a genetic trait associated with the clinical emergence of nalB-type multidrug resistance in P. aeruginosa during antibiotic treatment, we investigated the involvement of CpxR in regulating multidrug resistance among resistant isolates generated in the laboratory via antibiotic treatment and collected in clinical settings. CpxR is required to activate expression of mexAB-oprM and enhances drug resistance, in the absence or presence of MexR, in ofloxacin-cefsulodin-resistant isolates generated in the laboratory. Furthermore, CpxR was also important in the mexR-defective clinical isolates. The newly identified regulatory linkage between CpxR and the MexAB-OprM efflux pump highlights the presence of a complex regulatory network modulating multidrug resistance in P. aeruginosa. Pseudomonas aeruginosa is one of the major pathogens associated with cystic fibrosis and multidrug resistant P. aeruginosa has been listed as the Top 10 antibiotic resistance threats in the US CDC report (http://www.cdc.gov/drugresistance/biggest_threats.html). Drug efflux systems play a major role in multidrug resistance in P. aeruginosa. Currently, the regulatory networks modulating efflux pump expression are not fully understood. Here, we demonstrate that CpxR, a potentially multifaceted regulator, is directly involved in regulation of expression of MexAB-OprM, the major efflux pump in P. aeruginosa. The newly identified activator CpxR plays an important role in modulating multidrug resistance in nalB-type laboratory and clinical isolates. This work provides insight into the complex regulatory networks modulating multidrug resistance in P. aeruginosa.
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Affiliation(s)
- Zhe-Xian Tian
- State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing, China
- * E-mail: (ZXT); (YPW)
| | - Xue-Xian Yi
- State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing, China
| | - Anna Cho
- State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing, China
| | - Fergal O’Gara
- BIOMERIT Research Centre, Department of Microbiology, University College Cork, Cork, Ireland
- School of Biomedical Sciences, Curtin Health Innovation Research Institute, Curtin University, Perth, Western Australia, Australia
| | - Yi-Ping Wang
- State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing, China
- * E-mail: (ZXT); (YPW)
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Within-Host Evolution of the Dutch High-Prevalent Pseudomonas aeruginosa Clone ST406 during Chronic Colonization of a Patient with Cystic Fibrosis. PLoS One 2016; 11:e0158106. [PMID: 27337151 PMCID: PMC4918941 DOI: 10.1371/journal.pone.0158106] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 06/12/2016] [Indexed: 01/01/2023] Open
Abstract
This study investigates adaptation of ST406, a prevalent P. aeruginosa clone, present in 15% of chronically infected cystic fibrosis (CF) patients in the Netherlands, in a newly infected CF patient during three years using whole genome sequencing (WGS), transcriptomics, and phenotypic assays, including biofilm formation. WGS-based phylogeny demonstrates that ST406 is genetically distinct from other reported CF related strains or epidemic clones. Comparative genomic analysis of the early (S1) and late (S2) isolate yielded 42 single nucleotide polymorphisms (SNPs) and 10 indels and a single 7 kb genomic fragment only found in S2. Most SNPs and differentially expressed genes encoded proteins involved in metabolism, secretion and signal transduction or transcription. SNPs were identified in regulator genes mexT and exsA and coincided with differential gene expression of mexE and mexF, encoding the MexE/F efflux pump, genes encoding the type six secretion system (T6SS) and type three secretion system (T3SS), which have also been previously implicated in adaptation of other P. aeruginosa strains during chronic infection of CF lungs. The observation that genetically different strains from different patients have accumulated similar genetic adaptations supports the concept of adaptive parallel evolution of P. aeruginosa in chronically infected CF patients. Phenotypically, there was loss of biofilm maturation coinciding with a significant lower level of transcription of both bfmR and bfmS during chronic colonization. These data suggest that the high-prevalent Dutch CF clone ST406 displays adaptation to the CF lung niche, which involves a limited number of mutations affecting regulators controlling biofilm formation and secretion and genes involved in metabolism. These genes could provide good targets for anti-pseudomonal therapy.
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40
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Kasper SH, Bonocora RP, Wade JT, Musah RA, Cady NC. Chemical Inhibition of Kynureninase Reduces Pseudomonas aeruginosa Quorum Sensing and Virulence Factor Expression. ACS Chem Biol 2016; 11:1106-17. [PMID: 26785289 DOI: 10.1021/acschembio.5b01082] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The opportunistic pathogen Pseudomonas aeruginosa utilizes multiple quorum sensing (QS) pathways to coordinate an arsenal of virulence factors. We previously identified several cysteine-based compounds inspired by natural products from the plant Petiveria alliacea which are capable of antagonizing multiple QS circuits as well as reducing P. aeruginosa biofilm formation. To understand the global effects of such compounds on virulence factor production and elucidate their mechanism of action, RNA-seq transcriptomic analysis was performed on P. aeruginosa PAO1 exposed to S-phenyl-l-cysteine sulfoxide, the most potent inhibitor from the prior study. Exposure to this inhibitor down-regulated expression of several QS-regulated virulence operons (e.g., phenazine biosynthesis, type VI secretion systems). Interestingly, many genes that were differentially regulated pertain to the related metabolic pathways that yield precursors of pyochelin, tricarboxylic acid cycle intermediates, phenazines, and Pseudomonas quinolone signal (PQS). Activation of the MexT-regulon was also indicated, including the multidrug efflux pump encoded by mexEF-oprN, which has previously been shown to inhibit QS and pathogenicity. Deeper investigation of the metabolites involved in these systems revealed that S-phenyl-l-cysteine sulfoxide has structural similarity to kynurenine, a precursor of anthranilate, which is critical for P. aeruginosa virulence. By supplementing exogenous anthranilate, the QS-inhibitory effect was reversed. Finally, it was shown that S-phenyl-l-cysteine sulfoxide competitively inhibits P. aeruginosa kynureninase (KynU) activity in vitro and reduces PQS production in vivo. The kynurenine pathway has been implicated in P. aeruginosa QS and virulence factor expression; however, this is the first study to show that targeted inhibition of KynU affects P. aeruginosa gene expression and QS, suggesting a potential antivirulence strategy.
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Affiliation(s)
- Stephen H. Kasper
- Colleges
of Nanoscale Science and Engineering, SUNY Polytechnic Institute, Albany, New York, United States
| | - Richard P. Bonocora
- Wadsworth
Center, New York State Department of Health, Albany, New York, United States
| | - Joseph T. Wade
- Wadsworth
Center, New York State Department of Health, Albany, New York, United States
- Department
of Biomedical Sciences, School of Public Health, University at Albany, Albany, New York, United States
| | - Rabi Ann Musah
- Department
of Chemistry, University at Albany, SUNY, Albany, New York, United States
| | - Nathaniel C. Cady
- Colleges
of Nanoscale Science and Engineering, SUNY Polytechnic Institute, Albany, New York, United States
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Amino Acid Substitutions Account for Most MexS Alterations in Clinical nfxC Mutants of Pseudomonas aeruginosa. Antimicrob Agents Chemother 2016; 60:2302-10. [PMID: 26833155 DOI: 10.1128/aac.02622-15] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 01/25/2016] [Indexed: 11/20/2022] Open
Abstract
Multidrug-resistant mutants ofPseudomonas aeruginosathat overproduce the active efflux system MexEF-OprN (callednfxCmutants) have rarely been characterized in the hospital setting. Screening of 221 clinical strains exhibiting a reduced susceptibility to ciprofloxacin (a substrate of MexEF-OprN) and imipenem (a substrate of the negatively coregulated porin OprD) led to the identification of 43 (19.5%)nfxCmutants. Subsequent analysis of 22 nonredundant mutants showed that, in contrast to theirin vitro-selected counterparts, only 3 of them (13.6%) harbored a disruptedmexSgene, which codes for the oxidoreductase MexS, whose inactivation is known to activate themexEF-oprNoperon through a LysR-type regulator, MexT. Nine (40.9%) of the clinicalnfxCmutants contained single amino acid mutations in MexS, and these were associated with moderate effects on resistance and virulence factor production in 8/9 strains. Finally, the remaining 10 (45.5%)nfxCmutants did not display mutations in any of the regulators known to controlmexEF-oprNexpression (themexS,mexT,mvaT, andampRgenes), confirming that other loci are responsible for pump upregulation in patients. Collectively, these data demonstrate thatnfxCmutants are probably more frequent in the hospital than previously thought and have genetic and phenotypic features somewhat different from those ofin vitro-selected mutants.
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42
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Kreamer NN, Phillips R, Newman DK, Boedicker JQ. Predicting the impact of promoter variability on regulatory outputs. Sci Rep 2015; 5:18238. [PMID: 26675057 PMCID: PMC4682146 DOI: 10.1038/srep18238] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Accepted: 11/16/2015] [Indexed: 11/24/2022] Open
Abstract
The increased availability of whole genome sequences calls for quantitative models of global gene expression, yet predicting gene expression patterns directly from genome sequence remains a challenge. We examine the contributions of an individual regulator, the ferrous iron-responsive regulatory element, BqsR, on global patterns of gene expression in Pseudomonas aeruginosa. The position weight matrix (PWM) derived for BqsR uncovered hundreds of likely binding sites throughout the genome. Only a subset of these potential binding sites had a regulatory consequence, suggesting that BqsR/DNA interactions were not captured within the PWM or that the broader regulatory context at each promoter played a greater role in setting promoter outputs. The architecture of the BqsR operator was systematically varied to understand how binding site parameters influence expression. We found that BqsR operator affinity was predicted by the PWM well. At many promoters the surrounding regulatory context, including overlapping operators of BqsR or the presence of RhlR binding sites, were influential in setting promoter outputs. These results indicate more comprehensive models that include local regulatory contexts are needed to develop a predictive understanding of global regulatory outputs.
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Affiliation(s)
- Naomi N Kreamer
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA.,Department of Chemistry, California Institute of Technology, Pasadena, CA 91125, USA
| | - Rob Phillips
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA.,Department of Applied Physics, California Institute of Technology, Pasadena, CA 91125, USA
| | - Dianne K Newman
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA.,Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA
| | - James Q Boedicker
- Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089, USA.,Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
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Stability of the GraA Antitoxin Depends on Growth Phase, ATP Level, and Global Regulator MexT. J Bacteriol 2015; 198:787-96. [PMID: 26668267 DOI: 10.1128/jb.00684-15] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Accepted: 12/10/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Bacterial type II toxin-antitoxin systems consist of a potentially poisonous toxin and an antitoxin that inactivates the toxic protein by binding to it. Most of the toxins regulate stress survival, but their activation depends on the stability of the antitoxin that has to be degraded in order for the toxin to be able to attack its cellular targets. The degradation of antitoxins is usually rapid and carried out by ATP-dependent protease Lon or Clp, which is activated under stress conditions. The graTA system of Pseudomonas putida encodes the toxin GraT, which can affect the growth rate and stress tolerance of bacteria but is under most conditions inactivated by the unusually stable antitoxin GraA. Here, we aimed to describe the stability features of the antitoxin GraA by analyzing its degradation rate in total cell lysates of P. putida. We show that the degradation rate of GraA depends on the growth phase of bacteria being fastest in the transition from exponential to stationary phase. In accordance with this, higher ATP levels were shown to stabilize GraA. Differently from other antitoxins, the main cellular proteases Lon and Clp are not involved in GraA stability. Instead, GraA seems to be degraded through a unique pathway involving an endoprotease that cleaves the antitoxin into two unequal parts. We also identified the global transcriptional regulator MexT as a factor for destabilization of GraA, which indicates that the degradation of GraA may be induced by conditions similar to those that activate MexT. IMPORTANCE Toxin-antitoxin (TA) modules are widespread in bacterial chromosomes and have important roles in stress tolerance. As activation of a type II toxin is triggered by proteolytic degradation of the antitoxin, knowledge about the regulation of the antitoxin stability is critical for understanding the activation of a particular TA module. Here, we report on the unusual degradation pathway of the antitoxin GraA of the recently characterized GraTA system. While GraA is uncommonly stable in the exponential and late-stationary phases, its degradation increases in the transition phase. The degradation pathway of GraA involves neither Lon nor Clp, which usually targets antitoxins, but rather an unknown endoprotease and the global regulator MexT, suggesting a new type of regulation of antitoxin stability.
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Kim S, Yoon Y, Choi KH. Pseudomonas aeruginosa DesB Promotes Staphylococcus aureus Growth Inhibition in Coculture by Controlling the Synthesis of HAQs. PLoS One 2015; 10:e0134624. [PMID: 26230088 PMCID: PMC4521719 DOI: 10.1371/journal.pone.0134624] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 07/10/2015] [Indexed: 11/18/2022] Open
Abstract
Pseudomonas aeruginosa is a pathogen that can cause serious infections and usually coexists with other pathogens, such as Staphylococcus aureus. Virulence factors are important for maintaining a presence of the organisms in these multispecies environments, and DesB plays an important role in P. aeruginosa virulence. Therefore, we investigated the effect of DesB on S. aureus reduction under competitive situation. Liquid cultures of P. aeruginosa wild type (WT) and its desB mutant were spotted on agar plates containing S. aureus, and the size of the clear zones was compared. In addition, interbacterial competition between P. aeruginosa and S. aureus was observed over time during planktonic coculture. The transcriptional profiles of the WT and desB mutant were compared by qRT-PCR and microarray to determine the role of DesB in S. aureus reduction at the molecular level. As a result, the clear zone was smaller for the desB mutant than for P. aeruginosa PAO1 (WT), and in planktonic coculture, the number of S. aureus cells was reduced in the desB mutant. qRT-PCR and microarray revealed that the expression of MvfR-controlled pqsA-E and phnAB operons was significantly decreased, but the mexEF-oprN operon was highly expressed. The results indicate that intracellular levels of 4-hydroxy-2-heptylquinoline (HHQ), a ligand of MvfR, are reduced due to MexEF-OprN-mediated efflux in desB mutant, resulting in the decrease of MvfR binding to pqsA-E promoter and the reduction of 4-hydroxy-2-alkylquinolines (HAQs) synthesis. Overexpression of mexEF-oprN operon in desB mutant was phenotypically confirmed by observing significantly increased resistance to chloramphenicol. In conclusion, these results suggest that DesB plays a role in the inhibition of S. aureus growth by controlling HAQ synthesis.
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Affiliation(s)
- Sejeong Kim
- Department of Food and Nutrition, Sookmyung Women’s University, Seoul, Korea
| | - Yohan Yoon
- Department of Food and Nutrition, Sookmyung Women’s University, Seoul, Korea
- * E-mail: (YY); (KHC)
| | - Kyoung-Hee Choi
- Department of Oral Microbiology, College of Dentistry, Wonkwang University, Iksan, Korea
- * E-mail: (YY); (KHC)
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Li XZ, Plésiat P, Nikaido H. The challenge of efflux-mediated antibiotic resistance in Gram-negative bacteria. Clin Microbiol Rev 2015; 28:337-418. [PMID: 25788514 PMCID: PMC4402952 DOI: 10.1128/cmr.00117-14] [Citation(s) in RCA: 939] [Impact Index Per Article: 104.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The global emergence of multidrug-resistant Gram-negative bacteria is a growing threat to antibiotic therapy. The chromosomally encoded drug efflux mechanisms that are ubiquitous in these bacteria greatly contribute to antibiotic resistance and present a major challenge for antibiotic development. Multidrug pumps, particularly those represented by the clinically relevant AcrAB-TolC and Mex pumps of the resistance-nodulation-division (RND) superfamily, not only mediate intrinsic and acquired multidrug resistance (MDR) but also are involved in other functions, including the bacterial stress response and pathogenicity. Additionally, efflux pumps interact synergistically with other resistance mechanisms (e.g., with the outer membrane permeability barrier) to increase resistance levels. Since the discovery of RND pumps in the early 1990s, remarkable scientific and technological advances have allowed for an in-depth understanding of the structural and biochemical basis, substrate profiles, molecular regulation, and inhibition of MDR pumps. However, the development of clinically useful efflux pump inhibitors and/or new antibiotics that can bypass pump effects continues to be a challenge. Plasmid-borne efflux pump genes (including those for RND pumps) have increasingly been identified. This article highlights the recent progress obtained for organisms of clinical significance, together with methodological considerations for the characterization of MDR pumps.
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Affiliation(s)
- Xian-Zhi Li
- Human Safety Division, Veterinary Drugs Directorate, Health Products and Food Branch, Health Canada, Ottawa, Ontario, Canada
| | - Patrick Plésiat
- Laboratoire de Bactériologie, Faculté de Médecine-Pharmacie, Centre Hospitalier Régional Universitaire, Université de Franche-Comté, Besançon, France
| | - Hiroshi Nikaido
- Department of Molecular and Cell Biology, University of California, Berkeley, California, USA
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46
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Poole K. Stress responses as determinants of antimicrobial resistance in Pseudomonas aeruginosa: multidrug efflux and more. Can J Microbiol 2015; 60:783-91. [PMID: 25388098 DOI: 10.1139/cjm-2014-0666] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Pseudomonas aeruginosa is a notoriously antimicrobial-resistant organism that is increasingly refractory to antimicrobial chemotherapy. While the usual array of acquired resistance mechanisms contribute to resistance development in this organism a multitude of endogenous genes also play a role. These include a variety of multidrug efflux loci that contribute to both intrinsic and acquired antimicrobial resistance. Despite their roles in resistance, however, it is clear that these efflux systems function in more than just antimicrobial efflux. Indeed, recent data indicate that they are recruited in response to environmental stress and, therefore, function as components of the organism's stress responses. In fact, a number of endogenous resistance-promoting genes are linked to environmental stress, functioning as part of known stress responses or recruited in response to a variety of environmental stress stimuli. Stress responses are, thus, important determinants of antimicrobial resistance in P. aeruginosa. As such, they represent possible therapeutic targets in countering antimicrobial resistance in this organism.
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Affiliation(s)
- Keith Poole
- Department of Biomedical and Molecular Sciences, Botterell Hall, Queen's University, Kingston, ON K7L 3N6, Canada
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Pseudomonas aeruginosa LysR PA4203 regulator NmoR acts as a repressor of the PA4202 nmoA gene, encoding a nitronate monooxygenase. J Bacteriol 2014; 197:1026-39. [PMID: 25384477 DOI: 10.1128/jb.01991-14] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The PA4203 gene encodes a LysR regulator and lies between the ppgL gene (PA4204), which encodes a periplasmic gluconolactonase, and, in the opposite orientation, the PA4202 (nmoA) gene, coding for a nitronate monooxygenase, and ddlA (PA4201), encoding a d-alanine alanine ligase. The intergenic regions between PA4203 and ppgL and between PA4203 and nmoA are very short (79 and 107 nucleotides, respectively). Here we show that PA4203 (nmoR) represses its own transcription and the expression of nmoA. A chromatin immunoprecipitation analysis showed the presence of a single NmoR binding site between nmoA and nmoR, which was confirmed by electrophoretic mobility shift assays (EMSAs) with the purified NmoR protein. Despite this observation, a transcriptome analysis revealed more genes to be affected in an nmoR mutant, including genes known to be part of the MexT LysR activator regulon. The PA1225 gene, encoding a quinone oxidoreductase, was the most highly upregulated gene in the nmoR deletion mutant, independently of MexT. Finally, deletion of the nmoA gene resulted in an increased sensitivity of the cells to 3-nitropropionic acid (3-NPA), confirming the role of the nitronate monooxygenase protein in the detoxification of nitronate.
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McCarthy RR, Mooij MJ, Reen FJ, Lesouhaitier O, O'Gara F. A new regulator of pathogenicity (bvlR) is required for full virulence and tight microcolony formation in Pseudomonas aeruginosa. MICROBIOLOGY (READING, ENGLAND) 2014; 160:1488-1500. [PMID: 24829363 DOI: 10.1099/mic.0.075291-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
LysR-type transcriptional regulators (LTTRs) are the most common family of transcriptional regulators found in the opportunistic pathogen Pseudomonas aeruginosa. They are known to regulate a wide variety of virulence determinants and have emerged recently as positive global regulators of pathogenicity in a broad spectrum of important bacterial pathogens. However, in spite of their key role in modulating expression of key virulence determinants underpinning pathogenic traits associated with the process of infection, surprisingly few are found to be transcriptionally altered by contact with host cells. BvlR (PA14_26880) an LTTR of previously unknown function, has been shown to be induced in response to host cell contact, and was therefore investigated for its potential role in virulence. BvlR expression was found to play a pivotal role in the regulation of acute virulence determinants such as type III secretion system and exotoxin A production. BvlR also played a key role in P. aeruginosa pathogenicity within the Caenorhabditis elegans acute model of infection. Loss of BvlR led to an inability to form tight microcolonies, a key step in biofilm formation in the cystic fibrosis lung, although surface attachment was increased. Unusually for LTTRs, BvlR was shown to exert its influence through the transcriptional repression of many genes, including the virulence-associated cupA and alg genes. This highlights the importance of BvlR as a new virulence regulator in P. aeruginosa with a central role in modulating key events in the pathogen-host interactome.
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Affiliation(s)
- Ronan R McCarthy
- BIOMERIT Research Centre, School of Microbiology, University College Cork, Cork, Ireland
| | - Marlies J Mooij
- BIOMERIT Research Centre, School of Microbiology, University College Cork, Cork, Ireland
| | - F Jerry Reen
- BIOMERIT Research Centre, School of Microbiology, University College Cork, Cork, Ireland
| | - Olivier Lesouhaitier
- Laboratory of Microbiology Signals and Microenvironment LMSM EA4312, University of Rouen, 55 rue Saint Germain, 27000 Evreux, France
| | - Fergal O'Gara
- Curtin University, School of Biomedical Sciences, Perth, WA, Australia
- BIOMERIT Research Centre, School of Microbiology, University College Cork, Cork, Ireland
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Metabolic compensation of fitness costs associated with overexpression of the multidrug efflux pump MexEF-OprN in Pseudomonas aeruginosa. Antimicrob Agents Chemother 2014; 58:3904-13. [PMID: 24777101 DOI: 10.1128/aac.00121-14] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The acquisition of antibiotic resistance has been associated with a possible nonspecific, metabolic burden that is reflected in decreased fitness among resistant bacteria. We have recently demonstrated that overexpression of the MexEF-OprN multidrug efflux pump does not produce a metabolic burden when measured by classical competitions tests but rather leads to a number of changes in the organism's physiology. One of these changes is the untimely activation of the nitrate respiratory chain under aerobic conditions. MexEF-OprN is a proton/substrate antiporter. Overexpression of this element should result in a constant influx of protons, which may lead to cytoplasmic acidification. Acidification was not observed in aerobiosis, a situation in which the MexEF-overproducing mutant increases oxygen consumption. This enhanced oxygen uptake serves to eliminate intracellular proton accumulation, preventing the cytoplasmic acidification that was observed exclusively under anaerobic conditions, a situation in which the fitness of the MexEF-OprN-overproducing mutant decreases. Finally, we determined that the early activation of the nitrate respiratory chain under aerobic conditions plays a role in preventing a deleterious effect associated with the overexpression of MexEF-OprN. Our results show that metabolic rewiring may assist in overcoming the potential fitness cost associated with the acquisition of antibiotic resistance. Furthermore, the capability to metabolically compensate for this effect is habitat dependent, as demonstrated by our results under anaerobic conditions. The development of drugs that prevent metabolic compensation of fitness costs may help to reduce the persistence and dissemination of antibiotic resistance.
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Reen FJ, Barret M, Fargier E, O’Muinneacháin M, O’Gara F. Molecular evolution of LysR-type transcriptional regulation in Pseudomonas aeruginosa. Mol Phylogenet Evol 2013; 66:1041-9. [DOI: 10.1016/j.ympev.2012.12.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Revised: 12/13/2012] [Accepted: 12/17/2012] [Indexed: 11/25/2022]
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