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Schroven K, Putzeys L, Swinnen AL, Hendrix H, Paeshuyse J, Lavigne R. The phage-encoded protein PIT2 impacts Pseudomonas aeruginosa quorum sensing by direct interaction with LasR. iScience 2023; 26:107745. [PMID: 37736037 PMCID: PMC10509696 DOI: 10.1016/j.isci.2023.107745] [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: 03/27/2023] [Revised: 07/07/2023] [Accepted: 08/24/2023] [Indexed: 09/23/2023] Open
Abstract
In recent decades, there has been a notable increase in antibiotic-resistant Pseudomonas aeruginosa isolates, necessitating the development of innovative treatments to combat this pathogen. This manuscript explores the potential of different phage proteins to attenuate virulence factors of P. aeruginosa, particularly the type II secretion system (T2SS). PIT2, a protein derived from the lytic Pseudomonas phage LMA2 inhibits the T2SS effectors PrpL and LasA and attenuates the bacterial virulence toward HeLa cells and Galleria mellonella. Using RNAseq-based differential gene expression analysis, PIT2's impact on the LasR regulatory network is revealed, which plays a key role in bacterial quorum sensing. This discovery expands our knowledge on phage-encoded modulators of the bacterial metabolism and offers a promising anti-virulence target in P. aeruginosa. As such, it lays the foundation for a new phage-inspired anti-virulence strategy to combat multidrug resistant pathogens and opens the door for SynBio applications.
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Affiliation(s)
- Kaat Schroven
- Laboratory of Gene Technology, KU Leuven, 3000 Heverlee, Belgium
| | - Leena Putzeys
- Laboratory of Gene Technology, KU Leuven, 3000 Heverlee, Belgium
| | | | - Hanne Hendrix
- Laboratory of Gene Technology, KU Leuven, 3000 Heverlee, Belgium
| | - Jan Paeshuyse
- Laboratory for Host Pathogen Interactions in Livestock, KU Leuven, 3000 Heverlee, Belgium
| | - Rob Lavigne
- Laboratory of Gene Technology, KU Leuven, 3000 Heverlee, Belgium
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2
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Chen J, Yu X, Lu X, Wang W, Pan J, Yin Q, Wei B, Zhang H, Wang H. Biosynthesis and Gene Regulation of Rhamnolipid Congeners. Curr Microbiol 2023; 80:302. [PMID: 37493824 DOI: 10.1007/s00284-023-03405-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2023] [Accepted: 07/05/2023] [Indexed: 07/27/2023]
Abstract
Rhamnolipid congeners have been widely used in agriculture and biomedicine as potent surfactants. They have recently attracted attention due to their diverse and versatile biological functions, which include an important bacterial virulence factor that makes them attractive targets for research into biosynthetic pathways and gene regulation. The intricate gene expression and regulation network controlling their biosynthesis remain to be completely understood. This article summarizes current knowledge about the biosynthesis pathways and regulatory mechanisms of rhamnolipid congeners, that meet the pharmacological needs of human health and agriculture.
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Affiliation(s)
- Jianwei Chen
- College of Pharmaceutical Science & Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals & Key Laboratory for Green Pharmaceutical Technologies and Related Equipment of Ministry of Education & Key Laboratory, Pharmaceutical Engineering of Zhejiang Province, Zhejiang University of Technology, Hangzhou, China.
| | - Xiaoya Yu
- College of Pharmaceutical Science & Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals & Key Laboratory for Green Pharmaceutical Technologies and Related Equipment of Ministry of Education & Key Laboratory, Pharmaceutical Engineering of Zhejiang Province, Zhejiang University of Technology, Hangzhou, China
| | - Xingyue Lu
- College of Pharmaceutical Science & Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals & Key Laboratory for Green Pharmaceutical Technologies and Related Equipment of Ministry of Education & Key Laboratory, Pharmaceutical Engineering of Zhejiang Province, Zhejiang University of Technology, Hangzhou, China
| | - Wei Wang
- College of Pharmaceutical Science & Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals & Key Laboratory for Green Pharmaceutical Technologies and Related Equipment of Ministry of Education & Key Laboratory, Pharmaceutical Engineering of Zhejiang Province, Zhejiang University of Technology, Hangzhou, China
| | - Jiangwei Pan
- College of Pharmaceutical Science & Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals & Key Laboratory for Green Pharmaceutical Technologies and Related Equipment of Ministry of Education & Key Laboratory, Pharmaceutical Engineering of Zhejiang Province, Zhejiang University of Technology, Hangzhou, China
| | - Qunjian Yin
- Laboratory of Tropical Marine Ecosystem and Bioresource, Fourth Institute of Oceanography, Ministry of Natural Resources, Beihai, China
| | - Bin Wei
- College of Pharmaceutical Science & Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals & Key Laboratory for Green Pharmaceutical Technologies and Related Equipment of Ministry of Education & Key Laboratory, Pharmaceutical Engineering of Zhejiang Province, Zhejiang University of Technology, Hangzhou, China
| | - Huawei Zhang
- College of Pharmaceutical Science & Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals & Key Laboratory for Green Pharmaceutical Technologies and Related Equipment of Ministry of Education & Key Laboratory, Pharmaceutical Engineering of Zhejiang Province, Zhejiang University of Technology, Hangzhou, China
| | - Hong Wang
- College of Pharmaceutical Science & Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals & Key Laboratory for Green Pharmaceutical Technologies and Related Equipment of Ministry of Education & Key Laboratory, Pharmaceutical Engineering of Zhejiang Province, Zhejiang University of Technology, Hangzhou, China.
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3
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O'Connor K, Zhao CY, Mei M, Diggle SP. Frequency of quorum-sensing mutations in Pseudomonas aeruginosa strains isolated from different environments. MICROBIOLOGY (READING, ENGLAND) 2022; 168. [PMID: 36748632 DOI: 10.1099/mic.0.001265] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Pseudomonas aeruginosa uses quorum sensing (QS) to coordinate the expression of multiple genes necessary for establishing and maintaining infection. It has previously been shown that lasR QS mutations frequently arise in cystic fibrosis (CF) lung infections, however, there has been far less emphasis on determining whether other QS system mutations arise during infection or in other environments. To test this, we utilized 852 publicly available sequenced P. aeruginosa genomes from the Pseudomonas International Consortium Database (IPCD) to study P. aeruginosa QS mutational signatures. To study isolates by source, we focused on a subset of 654 isolates collected from CF, wounds, and non-infection environmental isolates, where we could clearly identify their source. We also worked with a small collection of isolates in vitro to determine the impact of lasR and pqs mutations on isolate phenotypes. We found that lasR mutations are common across all environments and are not specific to infection nor a particular infection type. We also found that the pqs system proteins PqsA, PqsH, PqsL and MexT, a protein of increasing importance to the QS field, are highly variable. Conversely, RsaL, a negative transcriptional regulator of the las system, was found to be highly conserved, suggesting selective pressure to repress las system activity. Overall, our findings suggest that QS mutations in P. aeruginosa are common and not limited to the las system; however, LasR is unique in the frequency of putative loss-of-function mutations.
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Affiliation(s)
- Kathleen O'Connor
- Center for Microbial Dynamics & Infection, School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Conan Y Zhao
- Center for Microbial Dynamics & Infection, School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Madeline Mei
- Center for Microbial Dynamics & Infection, School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Stephen P Diggle
- Center for Microbial Dynamics & Infection, School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
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4
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Genetic and Transcriptomic Characteristics of RhlR-Dependent Quorum Sensing in Cystic Fibrosis Isolates of Pseudomonas aeruginosa. mSystems 2022; 7:e0011322. [PMID: 35471121 PMCID: PMC9040856 DOI: 10.1128/msystems.00113-22] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
In people with the genetic disease cystic fibrosis (CF), bacterial infections involving the opportunistic pathogen Pseudomonas aeruginosa are a significant cause of morbidity and mortality. P. aeruginosa uses a cell-cell signaling mechanism called quorum sensing (QS) to regulate many virulence functions. One type of QS consists of acyl-homoserine lactone (AHL) signals produced by LuxI-type signal synthases, which bind a cognate LuxR-type transcription factor. In laboratory strains and conditions, P. aeruginosa employs two AHL synthase/receptor pairs arranged in a hierarchy, with the LasI/R system controlling the RhlI/R system and many downstream virulence factors. However, P. aeruginosa isolates with inactivating mutations in lasR are frequently isolated from chronic CF infections. We and others have shown that these isolates frequently use RhlR as the primary QS regulator. RhlR is rarely mutated in CF and environmental settings. We were interested in determining whether there were reproducible genetic characteristics of these isolates and whether there was a central group of genes regulated by RhlR in all isolates. We examined five isolates and found signatures of adaptation common to CF isolates. We did not identify a common genetic mechanism to explain the switch from Las- to Rhl-dominated QS. We describe a core RhlR regulon encompassing 20 genes encoding 7 products. These results suggest a key group of QS-regulated factors important for pathogenesis of chronic infections and position RhlR as a target for anti-QS therapeutics. Our work underscores the need to sample a diversity of isolates to understand QS beyond what has been described in laboratory strains. IMPORTANCE The bacterial pathogen Pseudomonas aeruginosa can cause chronic infections that are resistant to treatment in immunocompromised individuals. Over the course of these infections, the original infecting organism adapts to the host environment. P. aeruginosa uses a cell-cell signaling mechanism termed quorum sensing (QS) to regulate virulence factors and cooperative behaviors. The key QS regulator in laboratory strains, LasR, is frequently mutated in infection-adapted isolates, leaving another transcription factor, RhlR, in control of QS gene regulation. Such isolates provide an opportunity to understand Rhl-QS regulation without the confounding effects of LasR, as well as the scope of QS in the context of within-host evolution. We show that a core group of virulence genes is regulated by RhlR in a variety of infection-adapted LasR-null isolates. Our results reveal commonalities in infection-adapted QS gene regulation and key QS factors that may serve as therapeutic targets in the future.
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5
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Konikkat S, Scribner MR, Eutsey R, Hiller NL, Cooper VS, McManus J. Quantitative mapping of mRNA 3' ends in Pseudomonas aeruginosa reveals a pervasive role for premature 3' end formation in response to azithromycin. PLoS Genet 2021; 17:e1009634. [PMID: 34252072 PMCID: PMC8297930 DOI: 10.1371/journal.pgen.1009634] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 07/22/2021] [Accepted: 06/01/2021] [Indexed: 01/06/2023] Open
Abstract
Pseudomonas aeruginosa produces serious chronic infections in hospitalized patients and immunocompromised individuals, including patients with cystic fibrosis. The molecular mechanisms by which P. aeruginosa responds to antibiotics and other stresses to promote persistent infections may provide new avenues for therapeutic intervention. Azithromycin (AZM), an antibiotic frequently used in cystic fibrosis treatment, is thought to improve clinical outcomes through a number of mechanisms including impaired biofilm growth and quorum sensing (QS). The mechanisms underlying the transcriptional response to AZM remain unclear. Here, we interrogated the P. aeruginosa transcriptional response to AZM using a fast, cost-effective genome-wide approach to quantitate RNA 3’ ends (3pMap). We also identified hundreds of P. aeruginosa genes with high incidence of premature 3’ end formation indicative of riboregulation in their transcript leaders using 3pMap. AZM treatment of planktonic and biofilm cultures alters the expression of hundreds of genes, including those involved in QS, biofilm formation, and virulence. Strikingly, most genes downregulated by AZM in biofilms had increased levels of intragenic 3’ ends indicating premature transcription termination, transcriptional pausing, or accumulation of stable intermediates resulting from the action of nucleases. Reciprocally, AZM reduced premature intragenic 3’ end termini in many upregulated genes. Most notably, reduced termination accompanied robust induction of obgE, a GTPase involved in persister formation in P. aeruginosa. Our results support a model in which AZM-induced changes in 3’ end formation alter the expression of central regulators which in turn impairs the expression of QS, biofilm formation and stress response genes, while upregulating genes associated with persistence. Pseudomonas aeruginosa is a common source of hospital-acquired infections and causes prolonged illness in patients with cystic fibrosis. P. aeruginosa infections are often treated with the macrolide antibiotic azithromycin, which changes the expression of many genes involved in infection. By examining such expression changes at nucleotide resolution, we found azithromycin treatment alters the locations of mRNA 3’ ends suggesting most downregulated genes are subject to premature 3’ end formation. We further identified candidate RNA regulatory elements that P. aeruginosa may use to control gene expression. Our work provides new insights in P. aeruginosa gene regulation and its response to antibiotics.
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Affiliation(s)
- Salini Konikkat
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Michelle R. Scribner
- Department of Microbiology and Molecular Genetics, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Rory Eutsey
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - N. Luisa Hiller
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Vaughn S. Cooper
- Department of Microbiology and Molecular Genetics, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Joel McManus
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
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6
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Wang T, Sun W, Fan L, Hua C, Wu N, Fan S, Zhang J, Deng X, Yan J. An atlas of the binding specificities of transcription factors in Pseudomonas aeruginosa directs prediction of novel regulators in virulence. eLife 2021; 10:61885. [PMID: 33779544 PMCID: PMC8041468 DOI: 10.7554/elife.61885] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 03/26/2021] [Indexed: 12/14/2022] Open
Abstract
A high-throughput systematic evolution of ligands by exponential enrichment assay was applied to 371 putative TFs in Pseudomonas aeruginosa, which resulted in the robust enrichment of 199 unique sequence motifs describing the binding specificities of 182 TFs. By scanning the genome, we predicted in total 33,709 significant interactions between TFs and their target loci, which were more than 11-fold enriched in the intergenic regions but depleted in the gene body regions. To further explore and delineate the physiological and pathogenic roles of TFs in P. aeruginosa, we constructed regulatory networks for nine major virulence-associated pathways and found that 51 TFs were potentially significantly associated with these virulence pathways, 32 of which had not been characterized before, and some were even involved in multiple pathways. These results will significantly facilitate future studies on transcriptional regulation in P. aeruginosa and other relevant pathogens, and accelerate to discover effective treatment and prevention strategies for the associated infectious diseases.
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Affiliation(s)
- Tingting Wang
- Department of Biomedical Sciences, City University of Hong Kong, Kowloon Tong, Hong Kong SAR, China
| | - Wenju Sun
- School of Medicine, Northwest University, Xi'an, China
| | - Ligang Fan
- Department of Biomedical Sciences, City University of Hong Kong, Kowloon Tong, Hong Kong SAR, China.,School of Medicine, Northwest University, Xi'an, China
| | - Canfeng Hua
- Department of Biomedical Sciences, City University of Hong Kong, Kowloon Tong, Hong Kong SAR, China
| | - Nan Wu
- School of Medicine, Northwest University, Xi'an, China
| | - Shaorong Fan
- School of Medicine, Northwest University, Xi'an, China
| | - Jilin Zhang
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Solna, Sweden
| | - Xin Deng
- Department of Biomedical Sciences, City University of Hong Kong, Kowloon Tong, Hong Kong SAR, China
| | - Jian Yan
- Department of Biomedical Sciences, City University of Hong Kong, Kowloon Tong, Hong Kong SAR, China.,School of Medicine, Northwest University, Xi'an, China
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7
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Wicke L, Ponath F, Coppens L, Gerovac M, Lavigne R, Vogel J. Introducing differential RNA-seq mapping to track the early infection phase for Pseudomonas phage ɸKZ. RNA Biol 2020; 18:1099-1110. [PMID: 33103565 PMCID: PMC8244752 DOI: 10.1080/15476286.2020.1827785] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
As part of the ongoing renaissance of phage biology, more phage genomes are becoming available through DNA sequencing. However, our understanding of the transcriptome architecture that allows these genomes to be expressed during host infection is generally poor. Transcription start sites (TSSs) and operons have been mapped for very few phages, and an annotated global RNA map of a phage – alone or together with its infected host – is not available at all. Here, we applied differential RNA-seq (dRNA-seq) to study the early, host takeover phase of infection by assessing the transcriptome structure of Pseudomonas aeruginosa jumbo phage ɸKZ, a model phage for viral genetics and structural research. This map substantially expands the number of early expressed viral genes, defining TSSs that are active ten minutes after ɸKZ infection. Simultaneously, we record gene expression changes in the host transcriptome during this critical metabolism conversion. In addition to previously reported upregulation of genes associated with amino acid metabolism, we observe strong activation of genes with functions in biofilm formation (cdrAB) and iron storage (bfrB), as well as an activation of the antitoxin ParD. Conversely, ɸKZ infection rapidly down-regulates complexes IV and V of oxidative phosphorylation (atpCDGHF and cyoABCDE). Taken together, our data provide new insights into the transcriptional organization and infection process of the giant bacteriophage ɸKZ and adds a framework for the genome-wide transcriptomic analysis of phage–host interactions.
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Affiliation(s)
- Laura Wicke
- Institute for Molecular Infection Biology (IMIB), Medical Faculty, University of Würzburg, Würzburg, Germany.,Department of Biosystems, Laboratory of Gene Technology, KU Leuven, Leuven, Belgium
| | - Falk Ponath
- Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), Würzburg, Germany
| | - Lucas Coppens
- Department of Biosystems, Laboratory of Gene Technology, KU Leuven, Leuven, Belgium
| | - Milan Gerovac
- Institute for Molecular Infection Biology (IMIB), Medical Faculty, University of Würzburg, Würzburg, Germany
| | - Rob Lavigne
- Department of Biosystems, Laboratory of Gene Technology, KU Leuven, Leuven, Belgium
| | - Jörg Vogel
- Institute for Molecular Infection Biology (IMIB), Medical Faculty, University of Würzburg, Würzburg, Germany.,Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), Würzburg, Germany
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8
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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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Erwinia carotovora Quorum Sensing System Regulates Host-Specific Virulence Factors and Development Delay in Drosophila melanogaster. mBio 2020; 11:mBio.01292-20. [PMID: 32576677 PMCID: PMC7315124 DOI: 10.1128/mbio.01292-20] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Integration of genetic networks allows bacteria to rapidly adapt to changing environments. This is particularly important in bacteria that interact with multiple hosts. Erwinia carotovora is a plant pathogen that uses Drosophila melanogaster as a vector. To interact with these two hosts, Ecc15 uses different sets of virulence factors: plant cell wall-degrading enzymes to infect plants and the Erwinia virulence factor (evf) to infect Drosophila. Our work shows that, despite the virulence factors being specific for each host, both sets are coactivated by homoserine lactone quorum sensing and by the two-component GacS/A system in infected plants. This regulation is essential for Ecc15 loads in the gut of Drosophila and minimizes the developmental delay caused by the bacteria with respect to the insect vector. Our findings provide evidence that coactivation of the host-specific factors in the plant may function as a predictive mechanism to maximize the probability of transit of the bacteria between hosts. Multihost bacteria have to rapidly adapt to drastic environmental changes, relying on a fine integration of multiple stimuli for an optimal genetic response. Erwinia carotovora spp. are phytopathogens that cause soft-rot disease. Strain Ecc15 in particular is a model for bacterial oral-route infection in Drosophila melanogaster as it harbors a unique gene, evf, that encodes the Erwinia virulence factor (Evf), which is a major determinant for infection of the D. melanogaster gut. However, the factors involved in the regulation of evf expression are poorly understood. We investigated whether evf could be controlled by quorum sensing as, in the Erwinia genus, quorum sensing regulates pectolytic enzymes, the major virulence factors needed to infect plants. Here, we show that transcription of evf is positively regulated by quorum sensing in Ecc15 via acyl-homoserine lactone (AHL) signal synthase ExpI and AHL receptors ExpR1 and ExpR2. We also show that the load of Ecc15 in the gut depends upon the quorum sensing-mediated regulation of evf. Furthermore, we demonstrate that larvae infected with Ecc15 suffer a developmental delay as a direct consequence of the regulation of evf via quorum sensing. Finally, we demonstrate that evf is coexpressed with plant cell wall-degrading enzymes (PCWDE) during plant infection in a quorum sensing-dependent manner. Overall, our results show that Ecc15 relies on quorum sensing to control production of both pectolytic enzymes and Evf. This regulation influences the interaction of Ecc15 with its two known hosts, indicating that quorum sensing signaling may impact bacterial dissemination via insect vectors that feed on rotting plants.
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RhlR-Regulated Acyl-Homoserine Lactone Quorum Sensing in a Cystic Fibrosis Isolate of Pseudomonas aeruginosa. mBio 2020; 11:mBio.00532-20. [PMID: 32265330 PMCID: PMC7157775 DOI: 10.1128/mbio.00532-20] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Pseudomonas aeruginosa is a prominent cystic fibrosis (CF) pathogen that uses quorum sensing (QS) to regulate virulence. In laboratory strains, the key QS regulator is LasR. Many isolates from patients with chronic CF infections appear to use an alternate QS circuitry in which another transcriptional regulator, RhlR, mediates QS. We show that a LasR-null CF clinical isolate engages in QS through RhlR and remains capable of inducing cell death in an in vivo-like lung epithelium cell model. Our findings support the notion that LasR-null clinical isolates can engage in RhlR QS and highlight the centrality of RhlR in chronic P. aeruginosa infections. The opportunistic pathogen Pseudomonas aeruginosa is a leading cause of airway infection in cystic fibrosis (CF) patients. P. aeruginosa employs several hierarchically arranged and interconnected quorum sensing (QS) regulatory circuits to produce a battery of virulence factors such as elastase, phenazines, and rhamnolipids. The QS transcription factor LasR sits atop this hierarchy and activates the transcription of dozens of genes, including that encoding the QS regulator RhlR. Paradoxically, inactivating lasR mutations are frequently observed in isolates from CF patients with chronic P. aeruginosa infections. In contrast, mutations in rhlR are rare. We have recently shown that in CF isolates, the QS circuitry is often rewired such that RhlR acts in a LasR-independent manner. To begin understanding how QS activity differs in this rewired background, we characterized QS activation and RhlR-regulated gene expression in P. aeruginosa E90, a LasR-null, RhlR-active chronic infection isolate. In this isolate, RhlR activates the expression of 53 genes in response to increasing cell density. The genes regulated by RhlR include several that encode virulence factors. Some, but not all, of these genes are present in the QS regulon described in the well-studied laboratory strain PAO1. We also demonstrate that E90 produces virulence factors at similar concentrations as PAO1, and in E90, RhlR plays a significant role in mediating cytotoxicity in a three-dimensional lung epithelium cell model. These data illuminate a rewired LasR-independent RhlR regulon in chronic infection isolates and suggest further investigation of RhlR as a possible target for therapeutic development in chronic infections.
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11
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Multidrug Adaptive Resistance of Pseudomonas aeruginosa Swarming Cells. Antimicrob Agents Chemother 2020; 64:AAC.01999-19. [PMID: 31844008 DOI: 10.1128/aac.01999-19] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 12/10/2019] [Indexed: 01/25/2023] Open
Abstract
Swarming surface motility is a complex adaptation leading to multidrug antibiotic resistance and virulence factor production in Pseudomonas aeruginosa Here, we expanded previous studies to demonstrate that under swarming conditions, P. aeruginosa PA14 is more resistant to multiple antibiotics, including aminoglycosides, β-lactams, chloramphenicol, ciprofloxacin, tetracycline, trimethoprim, and macrolides, than swimming cells, but is not more resistant to polymyxin B. We investigated the mechanism(s) of swarming-mediated antibiotic resistance by examining the transcriptomes of swarming cells and swarming cells treated with tobramycin by transcriptomics (RNA-Seq) and reverse transcriptase quantitative PCR (qRT-PCR). RNA-Seq of swarming cells (versus swimming) revealed 1,581 dysregulated genes, including 104 transcriptional regulators, two-component systems, and sigma factors, numerous upregulated virulence and iron acquisition factors, and downregulated ribosomal genes. Strain PA14 mutants in resistome genes that were dysregulated under swarming conditions were tested for their ability to swarm in the presence of tobramycin. In total, 41 mutants in genes dysregulated under swarming conditions were shown to be more resistant to tobramycin under swarming conditions, indicating that swarming-mediated tobramycin resistance was multideterminant. Focusing on two genes downregulated under swarming conditions, both prtN and wbpW mutants were more resistant to tobramycin, while the prtN mutant was additionally resistant to trimethoprim under swarming conditions; complementation of these mutants restored susceptibility. RNA-Seq of swarming cells treated with subinhibitory concentrations of tobramycin revealed the upregulation of the multidrug efflux pump MexXY and downregulation of virulence factors.
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12
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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: 84] [Impact Index Per Article: 16.8] [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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Fernández M, Corral-Lugo A, Krell T. The plant compound rosmarinic acid induces a broad quorum sensing response in Pseudomonas aeruginosa PAO1. Environ Microbiol 2018; 20:4230-4244. [PMID: 30051572 DOI: 10.1111/1462-2920.14301] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Accepted: 05/28/2018] [Indexed: 02/05/2023]
Abstract
The interference of plant compounds with bacterial quorum sensing (QS) is a major mechanism through which plants and bacteria communicate. However, little is known about the modes of action and effects on signal integrity during this type of communication. We have recently shown that the plant compound rosmarinic acid (RA) specifically binds to the Pseudomonas aeruginosa RhlR QS receptor. To determine the effect of RA on expression patterns, we carried out global RNA-seq analysis. The results show that RA induces the expression of 128 genes, amongst which many virulence factor genes. RA triggers a broad QS response because 88% of the induced genes are known to be controlled by QS, and because RA stimulated genes were found to be involved in all four QS signalling systems within P. aeruginosa. This finding was confirmed through the analysis of transcriptional fusions transferred to wt and a rhlI/lasI double mutant. RA did not induce gene expression in the rhlI/lasI/rhlR triple mutant indicating that the effects observed are due to the RA-RhlR interaction. Furthermore, RA induced seven sRNAs that were all encoded in regions close to QS and/or RA induced genes. This work significantly enhances our understanding of plant bacteria interaction.
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Affiliation(s)
- Matilde Fernández
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Andrés Corral-Lugo
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain
- Institut de Biologie Intégrative de la Cellule (I2BC), CNRS, Gif-Sur-Yvette, France
| | - Tino Krell
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain
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RpoN-Dependent Direct Regulation of Quorum Sensing and the Type VI Secretion System in Pseudomonas aeruginosa PAO1. J Bacteriol 2018; 200:JB.00205-18. [PMID: 29760208 DOI: 10.1128/jb.00205-18] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Accepted: 05/09/2018] [Indexed: 12/23/2022] Open
Abstract
Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen of humans, particularly those with cystic fibrosis. As a global regulator, RpoN controls a group of virulence-related factors and quorum-sensing (QS) genes in P. aeruginosa To gain further insights into the direct targets of RpoN in vivo, the present study focused on identifying the direct targets of RpoN regulation in QS and the type VI secretion system (T6SS). We performed chromatin immunoprecipitation coupled with high-throughput sequencing (ChIP-seq) that identified 1,068 binding sites of RpoN, mostly including metabolic genes, a group of genes in QS (lasI, rhlI, and pqsR) and the T6SS (hcpA and hcpB). The direct targets of RpoN have been verified by electrophoretic mobility shifts assays (EMSA), lux reporter assay, reverse transcription-quantitative PCR, and phenotypic detection. The ΔrpoN::Tc mutant resulted in the reduced production of pyocyanin, motility, and proteolytic activity. However, the production of rhamnolipids and biofilm formation were higher in the ΔrpoN::Tc mutant than in the wild type. In summary, the results indicated that RpoN had direct and profound effects on QS and the T6SS.IMPORTANCE As a global regulator, RpoN controls a wide range of biological pathways, including virulence in P. aeruginosa PAO1. This work shows that RpoN plays critical and global roles in the regulation of bacterial pathogenicity and fitness. ChIP-seq provided a useful database to characterize additional functions and targets of RpoN in the future. The functional characterization of RpoN-mediated regulation will improve the current understanding of the regulatory network of quorum sensing and virulence in P. aeruginosa and other bacteria.
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Asfahl KL, Schuster M. Additive Effects of Quorum Sensing Anti-Activators on Pseudomonas aeruginosa Virulence Traits and Transcriptome. Front Microbiol 2018; 8:2654. [PMID: 29375519 PMCID: PMC5767178 DOI: 10.3389/fmicb.2017.02654] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 12/20/2017] [Indexed: 11/13/2022] Open
Abstract
In the opportunistic pathogen Pseudomonas aeruginosa, quorum sensing (QS) via acyl-homoserine lactone (AHL) signals coordinates virulence gene expression. AHL signals must reach a critical threshold before enough is bound by cognate regulators LasR and RhlR to drive transcription of target genes. In addition, three anti-activator proteins, QteE, QscR, and QslA, sequester QS regulators to increase the threshold for induction and delay expression of QS target genes. It remains unclear how multiple anti-activators work together to achieve the quorum threshold. Here, we employed a combination of mutational, kinetic, phenotypic, and transcriptomic analysis to examine regulatory effects and interactions of the three distinct anti-activators. We observed combinatorial, additive effects on QS gene expression. As measured by reporter gene fusion, individual deletion of each anti-activator gene increased lasB expression and QS-controlled virulence factor production. Deletion of qslA in combination with the deletion of any other anti-activator gene resulted in the greatest increase and earliest activation of lasB gene expression. Western analysis revealed that relative increases in soluble LasR in anti-activator mutants correlate with increased lasB expression and QS-controlled virulence factor production. RNA-seq of the previously uncharacterized QslA and QteE regulons revealed overlapping, yet distinct groups of differentially expressed genes. Simultaneous inactivation of qteE and qslA had the largest effect on gene expression with 999 genes induced and 798 genes repressed in the double mutant vs. wild-type. We found that LasR and RhlR-activated QS genes formed a subset of the genes induced in the qteE, qslA, and double mutant. The activation of almost all of these QS genes was advanced from stationary phase to log phase in the qteE qslA double mutant. Taken together, our results identify additive effects of anti-activation on QS gene expression, likely via LasR and RhlR, but do not rule out QS-independent effects.
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Affiliation(s)
- Kyle L Asfahl
- Department of Microbiology, Oregon State University, Corvallis, OR, United States
| | - Martin Schuster
- Department of Microbiology, Oregon State University, Corvallis, OR, United States
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He Q, Wang K, Su T, Wang F, Gu L, Xu S. Crystal structure of the N-terminal domain of VqsR from Pseudomonas aeruginosa at 2.1 Å resolution. Acta Crystallogr F Struct Biol Commun 2017; 73:431-436. [PMID: 28695853 PMCID: PMC5505249 DOI: 10.1107/s2053230x17009025] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Accepted: 06/16/2017] [Indexed: 11/10/2022] Open
Abstract
VqsR is a quorum-sensing (QS) transcriptional regulator which controls QS systems (las, rhl and pqs) by directly downregulating the expression of qscR in Pseudomonas aeruginosa. As a member of the LuxR family of proteins, VqsR shares the common motif of a helix-turn-helix (HTH)-type DNA-binding domain at the C-terminus, while the function of its N-terminal domain remains obscure. Here, the crystal structure of the N-terminal domain of VqsR (VqsR-N; residues 1-193) was determined at a resolution of 2.1 Å. The structure is folded into a regular α-β-α sandwich topology, which is similar to the ligand-binding domain (LBD) of the LuxR-type QS receptors. Although their sequence similarity is very low, structural comparison reveals that VqsR-N has a conserved enclosed cavity which could recognize acyl-homoserine lactones (AHLs) as in other LuxR-type AHL receptors. The structure suggests that VqsR could be a potential AHL receptor.
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Affiliation(s)
- Qing He
- State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, No. 27 Shanda South Road, Jinan, Shandong 250100, People’s Republic of China
| | - Kang Wang
- State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, No. 27 Shanda South Road, Jinan, Shandong 250100, People’s Republic of China
| | - Tiantian Su
- State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, No. 27 Shanda South Road, Jinan, Shandong 250100, People’s Republic of China
| | - Feng Wang
- State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, No. 27 Shanda South Road, Jinan, Shandong 250100, People’s Republic of China
| | - Lichuan Gu
- State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, No. 27 Shanda South Road, Jinan, Shandong 250100, People’s Republic of China
| | - Sujuan Xu
- State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, No. 27 Shanda South Road, Jinan, Shandong 250100, People’s Republic of China
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Yang J, Toyofuku M, Sakai R, Nomura N. Influence of the alginate production on cell-to-cell communication in Pseudomonas aeruginosa PAO1. ENVIRONMENTAL MICROBIOLOGY REPORTS 2017; 9:239-249. [PMID: 28120378 DOI: 10.1111/1758-2229.12521] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2016] [Revised: 01/13/2017] [Accepted: 01/18/2017] [Indexed: 06/06/2023]
Abstract
Many bacteria communicate with each other through signalling molecules, a process known as cell-to-cell communication. During this process, it is important for the signalling molecules to: (1) reach the target cells; and (2) to be received by the cognate receptor. Barriers such as the presence of extracellular matrix may prevent signals from reaching their targets; however, the influence of the extracellular matrix on cell-to-cell communication has scarcely been studied. Here, we demonstrate that the overproduction of an extracellular matrix, alginate, in a Pseudomonas aeruginosa mucoid variant, alters cell-to-cell communication by interfering with the response to quinolone signals while having no effect on N-acyl-L-homoserine lactones. The inhibition of quinolone signalling by alginate is limited to the alginate overproducer and has no effect on neighbour cells that do not produce alginate. Our study indicates that alginate overproduction affects the cell-to-cell communication of the mucoid variant, which may results in different downstream behaviours when it emerges in the presence of the wild-type (WT).
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Affiliation(s)
- Jiayue Yang
- Department of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8572, Japan
| | - Masanori Toyofuku
- Department of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8572, Japan
- Department of Plant and Microbial Biology, University of Zurich, Zürich, 8008, Switzerland
| | - Ryosuke Sakai
- Department of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8572, Japan
| | - Nobuhiko Nomura
- Department of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8572, Japan
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Viducic D, Murakami K, Amoh T, Ono T, Miyake Y. Role of the interplay between quorum sensing regulator VqsR and the Pseudomonas quinolone signal in mediating carbapenem tolerance in Pseudomonas aeruginosa. Res Microbiol 2017; 168:450-460. [PMID: 28263907 DOI: 10.1016/j.resmic.2017.02.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 02/12/2017] [Accepted: 02/14/2017] [Indexed: 12/25/2022]
Abstract
Pseudomonas aeruginosa coordinates its response to environmental conditions through activation of a quorum sensing (QS) system. In this study, we investigated the regulatory interaction between the QS transcriptional regulator VqsR and the Pseudomonas quinolone signal (PQS) through integration of sigma factor RpoS, and we addressed whether one of the pathways controlling carbapenem tolerance can be attributed to VqsR. We demonstrate that vqsR expression at the transcriptional level is regulated by pqsA, pqsR, and pqsE. Assessment of the transcriptional expression of vqsR, lasI, rhlI, and qscR in ΔpqsA and ΔpqsAΔrpoS mutants provided insight into pqsA- and rpoS-dependent regulation of vqsR and vqsR-controlled genes. Exogenously supplemented PQS reversed expression of vqsR and vqsR-controlled genes in the ΔpqsA mutant to wild-type levels, but failed to increase expression levels of lasI and qscR in the ΔpqsAΔrpoS mutant to levels observed in wild-type PAO1. The ΔvqsR mutant showed reduced survival when challenged with carbapenems compared to wild-type PAO1. Introduction of a pqsA mutation into the ΔvqsR mutant completely abolished its carbapenem-sensitive phenotype. We conclude that a regulatory link between PQS and vqsR exists, and that RpoS is important in their interaction. We also demonstrate that VqsR affects carbapenem tolerance.
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Affiliation(s)
- Darija Viducic
- Department of Oral Microbiology, Institute of Biomedical Sciences, Tokushima University Graduate School, Kuramoto-cho 3-18-15, Tokushima 770-8504, Japan; Department of Molecular Microbiology, Institute of Health Biosciences, Tokushima University Graduate School, Kuramoto-cho 3-18-15, Tokushima 770-8509, Japan.
| | - Keiji Murakami
- Department of Oral Microbiology, Institute of Biomedical Sciences, Tokushima University Graduate School, Kuramoto-cho 3-18-15, Tokushima 770-8504, Japan.
| | - Takashi Amoh
- Department of Oral Microbiology, Institute of Biomedical Sciences, Tokushima University Graduate School, Kuramoto-cho 3-18-15, Tokushima 770-8504, Japan.
| | - Tsuneko Ono
- Department of Molecular Microbiology, Institute of Health Biosciences, Tokushima University Graduate School, Kuramoto-cho 3-18-15, Tokushima 770-8509, Japan.
| | - Yoichiro Miyake
- Department of Oral Microbiology, Institute of Biomedical Sciences, Tokushima University Graduate School, Kuramoto-cho 3-18-15, Tokushima 770-8504, Japan.
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RpoN Modulates Carbapenem Tolerance in Pseudomonas aeruginosa through Pseudomonas Quinolone Signal and PqsE. Antimicrob Agents Chemother 2016; 60:5752-64. [PMID: 27431228 DOI: 10.1128/aac.00260-16] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Accepted: 07/05/2016] [Indexed: 01/09/2023] Open
Abstract
The ability of Pseudomonas aeruginosa to rapidly modulate its response to antibiotic stress and persist in the presence of antibiotics is closely associated with the process of cell-to-cell signaling. The alternative sigma factor RpoN (σ(54)) is involved in the regulation of quorum sensing (QS) and plays an important role in the survival of stationary-phase cells in the presence of carbapenems. Here, we demonstrate that a ΔrpoN mutant grown in nutrient-rich medium has increased expression of pqsA, pqsH, and pqsR throughout growth, resulting in the increased production of the Pseudomonas quinolone signal (PQS). The link between pqsA and its role in carbapenem tolerance was studied using a ΔrpoN ΔpqsA mutant, in which the carbapenem-tolerant phenotype of the ΔrpoN mutant was abolished. In addition, we demonstrate that another mechanism leading to carbapenem tolerance in the ΔrpoN mutant is mediated through pqsE Exogenously supplied PQS abolished the biapenem-sensitive phenotype of the ΔrpoN ΔpqsA mutant, and overexpression of pqsE failed to alter the susceptibility of the ΔrpoN ΔpqsA mutant to biapenem. The mutations in the ΔrpoN ΔrhlR mutant and the ΔrpoN ΔpqsH mutant led to susceptibility to biapenem. Comparison of the changes in the expression of the genes involved in QS in wild-type PAO1 with their expression in the ΔrpoN mutant and the ΔrpoN mutant-derived strains demonstrated the regulatory effect of RpoN on the transcript levels of rhlR, vqsR, and rpoS The findings of this study demonstrate that RpoN negatively regulates the expression of PQS in nutrient-rich medium and provide evidence that RpoN interacts with pqsA, pqsE, pqsH, and rhlR in response to antibiotic stress.
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Singh BN, Prateeksha, Upreti DK, Singh BR, Defoirdt T, Gupta VK, De Souza AO, Singh HB, Barreira JCM, Ferreira ICFR, Vahabi K. Bactericidal, quorum quenching and anti-biofilm nanofactories: a new niche for nanotechnologists. Crit Rev Biotechnol 2016; 37:525-540. [PMID: 27684212 DOI: 10.1080/07388551.2016.1199010] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Despite several conventional potent antibacterial therapies, bacterial infections pose a significant threat to human health because they are emerging as the leading cause of death worldwide. Due to the development of antibiotic resistance in bacteria, there is a pressing demand to discover novel approaches for developing more effective therapies to treat multidrug-resistant bacterial strains and biofilm-associated infections. Therefore, attention has been especially devoted to a new and emerging branch of science "nanotechnology" to design non-conventional antimicrobial chemotherapies. A range of nanomaterials and nano-sized carriers for conventional antimicrobial agents have fully justified their potential to combat bacterial diseases by reducing cell viability, by attenuating quorum sensing, and by inhibiting/or eradicating biofilms. This communication summarizes emerging nano-antimicrobial therapies in treating bacterial infections, particularly using antibacterial, quorum quenching, and anti-biofilm nanomaterials as new approaches to tackle the current challenges in combating infectious diseases.
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Affiliation(s)
- Brahma N Singh
- a Pharmacognosy & Ethnopharmacology Division , CSIR-National Botanical Research Institute , Lucknow , India
| | - Prateeksha
- a Pharmacognosy & Ethnopharmacology Division , CSIR-National Botanical Research Institute , Lucknow , India
| | - Dalip K Upreti
- b Lichenology laboratory , Plant Biodiversity and Conservation Biology Division, CSIR-National Botanical Research Institute , Lucknow , Uttar Pradesh , India
| | - Braj Raj Singh
- c TERI-Deakin Nanobiotechnology Centre, TERI Gram, The Energy and Resources Institute, Gurgaon , Haryana , India.,d Centre of Excellence in Materials Science (Nanomaterials), Z. H. College of Engineering and Technology , Aligarh Muslim University, Aligarh , Uttar Pradesh , India
| | - Tom Defoirdt
- d Centre of Excellence in Materials Science (Nanomaterials), Z. H. College of Engineering and Technology , Aligarh Muslim University, Aligarh , Uttar Pradesh , India.,e Laboratory of Aquaculture & Artemia Reference Center , Ghent University , Gent , Belgium
| | - Vijai K Gupta
- f Molecular Glyco-biotechnology Group, Discipline of Biochemistry , School of Natural Sciences, National University of Ireland Galway , Galway , Ireland
| | | | - Harikesh Bahadur Singh
- h Mycology & Plant Pathology, Institute of Agricultural Sciences, Banaras Hindu University , Varanasi , Uttar Pardesh , India
| | - João C M Barreira
- i Mountain Research Centre (CIMO), ESA, Polytechnic Institute of Bragança , Campus de Santa Apolónia , Bragança , Portugal
| | - Isabel C F R Ferreira
- i Mountain Research Centre (CIMO), ESA, Polytechnic Institute of Bragança , Campus de Santa Apolónia , Bragança , Portugal
| | - Khabat Vahabi
- j Biologisch-Pharmazeutische Fakultät , Institut für Allgemeine Botanik und Pflanzenphysiologie, Friedrich-Schiller Universität Jena , Jena , Germany
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Li Y, Bai F, Xia H, Zhuang L, Xu H, Jin Y, Zhang X, Bai Y, Qiao M. A novel regulator PA5022 (aefA) is involved in swimming motility, biofilm formation and elastase activity of Pseudomonas aeruginosa. Microbiol Res 2015; 176:14-20. [DOI: 10.1016/j.micres.2015.04.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Revised: 03/27/2015] [Accepted: 04/01/2015] [Indexed: 10/23/2022]
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Yang N, Ding S, Chen F, Zhang X, Xia Y, Di H, Cao Q, Deng X, Wu M, Wong CCL, Tian XX, Yang CG, Zhao J, Lan L. The Crc protein participates in down-regulation of the Lon gene to promote rhamnolipid production and rhl quorum sensing in Pseudomonas aeruginosa. Mol Microbiol 2015; 96:526-47. [PMID: 25641250 DOI: 10.1111/mmi.12954] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/28/2015] [Indexed: 12/20/2022]
Abstract
Rhamnolipid acts as a virulence factor during Pseudomonas aeruginosa infection. Here, we show that deletion of the catabolite repression control (crc) gene in P. aeruginosa leads to a rhamnolipid-negative phenotype. This effect is mediated by the down-regulation of rhl quorum sensing (QS). We discover that a disruption of the gene encoding the Lon protease entirely offsets the effect of crc deletion on the production of both rhamnolipid and rhl QS signal C4-HSL. Crc is unable to bind lon mRNA in vitro in the absence of the RNA chaperon Hfq, while Crc contributes to Hfq-mediated repression of the lon gene expression at a posttranscriptional level. Deletion of crc, which results in up-regulation of lon, significantly reduces the in vivo stability and abundance of the RhlI protein that synthesizes C4-HSL, causing the attenuation of rhl QS. Lon is also capable of degrading the RhlI protein in vitro. In addition, constitutive expression of rhlI suppresses the defects of the crc deletion mutant in rhamnolipid, C4-HSL and virulence on lettuce leaves. This study therefore uncovers a novel posttranscriptional regulatory cascade, Crc-Hfq/Lon/RhlI, for the regulation of rhamnolipid production and rhl QS in P. aeruginosa.
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Affiliation(s)
- Nana Yang
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Pudong Zhangjiang Hi-Tech Park, Shanghai, 201203, China
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Chugani S, Greenberg EP. An evolving perspective on the Pseudomonas aeruginosa orphan quorum sensing regulator QscR. Front Cell Infect Microbiol 2014; 4:152. [PMID: 25389523 PMCID: PMC4211393 DOI: 10.3389/fcimb.2014.00152] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 10/10/2014] [Indexed: 11/22/2022] Open
Abstract
Many Proteobacteria govern responses to changes in cell density by using acyl-homoserine lactone (AHL) quorum-sensing (QS) signaling. Similar to the LuxI-LuxR system described in Vibrio fischeri, a minimal AHL QS circuit comprises a pair of genes, a luxI-type synthase gene encoding an enzyme that synthesizes an AHL and a luxR-type AHL-responsive transcription regulator gene. In most bacteria that utilize AHL QS, cognate luxI and luxR homologs are found in proximity to each other on the chromosome. However, a number of recent reports have identified luxR homologs that are not linked to luxI homologs; in some cases luxR homologs have been identified in bacteria that have no luxI homologs. A luxR homolog without a linked luxI homologs is termed an orphan or solo. One of the first reports of an orphan was on QscR in Pseudomonas aeruginosa. The qscR gene was revealed by whole genome sequencing and has been studied in some detail. P. aeruginosa encodes two AHL synthases and three AHL responsive receptors, LasI-LasR form a cognate synthase-receptor pair as do RhlI-RhlR. QscR lacks a linked synthase and responds to the LasI-generated AHL. QS regulation of gene expression in P. aeruginosa employs multiple signals and occurs in the context of other interconnected regulatory circuits that control diverse physiological functions. QscR affects virulence of P. aeruginosa, and although it shows sensitivity to the LasI-generated AHL, 3-oxo-dodecanoylhomoserine lactone, it's specificity is relaxed compared to LasR and can respond equally well to several AHLs. QscR controls a set of genes that overlaps the set regulated by LasR. QscR is comparatively easy to purify and study in vitro, and has become a model for understanding the biochemistry of LuxR homologs. In fact there is a crystal structure of QscR bound to the LasI-generated AHL. Here, we review the current state of research concerning QscR and highlight recent advances in our understanding of its structure and biochemistry.
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Affiliation(s)
- Sudha Chugani
- Department of Microbiology, University of Washington Seattle, WA, USA
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Cao Q, Wang Y, Chen F, Xia Y, Lou J, Zhang X, Yang N, Sun X, Zhang Q, Zhuo C, Huang X, Deng X, Yang CG, Ye Y, Zhao J, Wu M, Lan L. A novel signal transduction pathway that modulates rhl quorum sensing and bacterial virulence in Pseudomonas aeruginosa. PLoS Pathog 2014; 10:e1004340. [PMID: 25166864 PMCID: PMC4148453 DOI: 10.1371/journal.ppat.1004340] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Accepted: 07/15/2014] [Indexed: 01/10/2023] Open
Abstract
The rhl quorum-sensing (QS) system plays critical roles in the pathogenesis of P. aeruginosa. However, the regulatory effects that occur directly upstream of the rhl QS system are poorly understood. Here, we show that deletion of gene encoding for the two-component sensor BfmS leads to the activation of its cognate response regulator BfmR, which in turn directly binds to the promoter and decreases the expression of the rhlR gene that encodes the QS regulator RhlR, causing the inhibition of the rhl QS system. In the absence of bfmS, the Acka-Pta pathway can modulate the regulatory activity of BfmR. In addition, BfmS tunes the expression of 202 genes that comprise 3.6% of the P. aeruginosa genome. We further demonstrate that deletion of bfmS causes substantially reduced virulence in lettuce leaf, reduced cytotoxicity, enhanced invasion, and reduced bacterial survival during acute mouse lung infection. Intriguingly, specific missense mutations, which occur naturally in the bfmS gene in P. aeruginosa cystic fibrosis (CF) isolates such as DK2 strains and RP73 strain, can produce BfmS variants (BfmSL181P, BfmSL181P/E376Q, and BfmSR393H) that no longer repress, but instead activate BfmR. As a result, BfmS variants, but not the wild-type BfmS, inhibit the rhl QS system. This study thus uncovers a previously unexplored signal transduction pathway, BfmS/BfmR/RhlR, for the regulation of rhl QS in P. aeruginosa. We propose that BfmRS TCS may have an important role in the regulation and evolution of P. aeruginosa virulence during chronic infection in CF lungs. The rhl quorum-sensing (QS) system allows P. aeruginosa to regulate diverse metabolic adaptations and virulence. However, how rhl QS system is regulated remains largely unknown. Here, we report that two-component sensor BfmS controls rhl QS system by repressing its cognate response regulator BfmR, which directly suppresses the expression of rhl QS regulator RhlR gene and reduces the production of QS signal molecule N-butanoyl-L-homoserine lactone (C4-HSL). We find that BfmS is critical to the ability of P. aeruginosa to modulate the expression of virulence-associated traits and adapt to the host. Intriguingly, although wild-type BfmS is a repressor of BfmR, naturally occurring missense mutation (L181P, L181P/E376Q, or R393H) can convert its function from a repressor to an activator of BfmR, leading to BfmR activation, which in turn reduces the level of rhl QS signal C4-HSL. These results, therefore, provide important and novel insight into the regulation and evolution of P. aeruginosa virulence.
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Affiliation(s)
- Qiao Cao
- Hainan University, Haikou, Hainan, China
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Yue Wang
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
- Institute of Chemistry and BioMedical Sciences, State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
| | - Feifei Chen
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Yongjie Xia
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Jingyu Lou
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Xue Zhang
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Nana Yang
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Xiaoxu Sun
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Qin Zhang
- State Key Laboratory of Respiratory Diseases and the First Affiliated Hospital of Guangzhou Medical College, Guangzhou, China
| | - Chao Zhuo
- State Key Laboratory of Respiratory Diseases and the First Affiliated Hospital of Guangzhou Medical College, Guangzhou, China
| | - Xi Huang
- Hainan University, Haikou, Hainan, China
| | - Xin Deng
- Department of Chemistry and Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois, United States of America
| | - Cai-Guang Yang
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Yan Ye
- Department of Basic Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, United States of America
| | - Jing Zhao
- Institute of Chemistry and BioMedical Sciences, State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
- * E-mail: (JZ); (MW); (LL)
| | - Min Wu
- Department of Basic Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, United States of America
- * E-mail: (JZ); (MW); (LL)
| | - Lefu Lan
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
- * E-mail: (JZ); (MW); (LL)
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Liang H, Deng X, Li X, Ye Y, Wu M. Molecular mechanisms of master regulator VqsM mediating quorum-sensing and antibiotic resistance in Pseudomonas aeruginosa. Nucleic Acids Res 2014; 42:10307-20. [PMID: 25034696 PMCID: PMC4176358 DOI: 10.1093/nar/gku586] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The Pseudomonas aeruginosa quorum-sensing (QS) systems contribute to bacterial homeostasis and pathogenicity. Although the AraC-family transcription factor VqsM has been characterized to control the production of virulence factors and QS signaling molecules, its detailed regulatory mechanisms still remain elusive. Here, we report that VqsM directly binds to the lasI promoter region, and thus regulates its expression. To identify additional targets of VqsM in P. aeruginosa PAO1, we performed chromatin immunoprecipitation (ChIP) followed by high-throughput DNA sequencing (ChIP-seq) and detected 48 enriched loci harboring VqsM-binding peaks in the P. aeruginosa genome. The direct regulation of these genes by VqsM has been confirmed by electrophoretic mobility shift assays and quantitative real-time polymerase chain reactions. A VqsM-binding motif was identified by using the MEME suite and verified by footprint assays in vitro. In addition, VqsM directly bound to the promoter regions of the antibiotic resistance regulator NfxB and the master type III secretion system (T3SS) regulator ExsA. Notably, the vqsM mutant displayed more resistance to two types of antibiotics and promoted bacterial survival in a mouse model, compared to wild-type PAO1. Collectively, this work provides new cues to better understand the detailed regulatory networks of QS systems, T3SS, and antibiotic resistance.
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Affiliation(s)
- Haihua Liang
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Science, Northwest University, Xi'an, ShaanXi 710069, China Department of Chemistry and Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL 60637, USA
| | - Xin Deng
- Department of Chemistry and Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL 60637, USA
| | - Xuefeng Li
- Department of Basic Science, School of Medicine and Health Science, University of North Dakota, 501 North Columbia Rd, EJRF Building, Room 2726, ND 58203, USA
| | - Yan Ye
- Department of Basic Science, School of Medicine and Health Science, University of North Dakota, 501 North Columbia Rd, EJRF Building, Room 2726, ND 58203, USA
| | - Min Wu
- Department of Basic Science, School of Medicine and Health Science, University of North Dakota, 501 North Columbia Rd, EJRF Building, Room 2726, ND 58203, USA
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The Impact of Anaerobiosis on Strain-Dependent Phenotypic Variations inPseudomonas aeruginosa. Biosci Biotechnol Biochem 2014; 77:1747-52. [DOI: 10.1271/bbb.130309] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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A new synthetic ligand that activates QscR and blocks antibiotic-tolerant biofilm formation in Pseudomonas aeruginosa. Appl Microbiol Biotechnol 2013; 98:2565-72. [DOI: 10.1007/s00253-013-5420-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 11/01/2013] [Accepted: 11/18/2013] [Indexed: 10/25/2022]
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Castelhano Santos N, Pereira MO, Lourenço A. Pathogenicity phenomena in three model systems: from network mining to emerging system-level properties. Brief Bioinform 2013; 16:169-82. [PMID: 24106130 DOI: 10.1093/bib/bbt071] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Understanding the interconnections of microbial pathogenicity phenomena, such as biofilm formation, quorum sensing and antimicrobial resistance, is a tremendous open challenge for biomedical research. Progress made by wet-lab researchers and bioinformaticians in understanding the underlying regulatory phenomena has been significant, with converging evidence from multiple high-throughput technologies. Notably, network reconstructions are already of considerable size and quality, tackling both intracellular regulation and signal mediation in microbial infection. Therefore, it stands to reason that in silico investigations would play a more active part in this research. Drug target identification and drug repurposing could take much advantage of the ability to simulate pathogen regulatory systems, host-pathogen interactions and pathogen cross-talking. Here, we review the bioinformatics resources and tools available for the study of the gram-negative bacterium Pseudomonas aeruginosa, the gram-positive bacterium Staphylococcus aureus and the fungal species Candida albicans. The choice of these three microorganisms fits the rationale of the review converging into pathogens of great clinical importance, which thrive in biofilm consortia and manifest growing antimicrobial resistance.
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Schaadt NS, Steinbach A, Hartmann RW, Helms V. Rule-based regulatory and metabolic model for Quorum sensing in P. aeruginosa. BMC SYSTEMS BIOLOGY 2013; 7:81. [PMID: 23965312 PMCID: PMC3765737 DOI: 10.1186/1752-0509-7-81] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Accepted: 08/09/2013] [Indexed: 12/24/2022]
Abstract
Background In the pathogen P. aeruginosa, the formation of virulence factors is regulated via Quorum sensing signaling pathways. Due to the increasing number of strains that are resistant to antibiotics, there is a high interest to develop novel antiinfectives. In the combat of resistant bacteria, selective blockade of the bacterial cell–to–cell communication (Quorum sensing) has gained special interest as anti–virulence strategy. Here, we modeled the las, rhl, and pqs Quorum sensing systems by a multi–level logical approach to analyze how enzyme inhibitors and receptor antagonists effect the formation of autoinducers and virulence factors. Results Our rule–based simulations fulfill the behavior expected from literature considering the external level of autoinducers. In the presence of PqsBCD inhibitors, the external HHQ and PQS levels are indeed clearly reduced. The magnitude of this effect strongly depends on the inhibition level. However, it seems that the pyocyanin pathway is incomplete. Conclusions To match experimental observations we suggest a modified network topology in which PqsE and PqsR acts as receptors and an autoinducer as ligand that up–regulate pyocyanin in a concerted manner. While the PQS biosynthesis is more appropriate as target to inhibit the HHQ and PQS formation, blocking the receptor PqsR that regulates the biosynthesis reduces the pyocyanin level stronger.
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Affiliation(s)
- Nadine S Schaadt
- Center for Bioinformatics, Saarland University, Campus E2,1, 66123 Saarbrücken, Germany.
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Jakobsen TH, Bjarnsholt T, Jensen PØ, Givskov M, Høiby N. Targeting quorum sensing in Pseudomonas aeruginosa biofilms: current and emerging inhibitors. Future Microbiol 2013; 8:901-21. [DOI: 10.2217/fmb.13.57] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Bacterial resistance to conventional antibiotics combined with an increasing acknowledgement of the role of biofilms in chronic infections has led to a growing interest in new antimicrobial strategies that target the biofilm mode of growth. In the aggregated biofilm mode, cell-to-cell communication systems involved in the process known as quorum sensing regulate coordinated expression of virulence with immune shielding mechanisms and antibiotic resistance. For two decades, the potential of interference with quorum sensing by small chemical compounds has been investigated with the aim of developing alternative antibacterial strategies. Here, we review state of the art research of quorum sensing inhibitors against the opportunistic human pathogen Pseudomonas aeruginosa, which is found in a number of biofilm-associated infections and identified as the predominant organism infecting the lungs of cystic fibrosis patients.
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Affiliation(s)
- Tim Holm Jakobsen
- Costerton Biofilm Center, Department of International Health, Immunology & Microbiology, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Thomas Bjarnsholt
- Costerton Biofilm Center, Department of International Health, Immunology & Microbiology, University of Copenhagen, DK-2200 Copenhagen, Denmark
- Department of Clinical Microbiology, Rigshospitalet, DK-2100 Copenhagen, Denmark
| | - Peter Østrup Jensen
- Department of Clinical Microbiology, Rigshospitalet, DK-2100 Copenhagen, Denmark
| | - Michael Givskov
- Costerton Biofilm Center, Department of International Health, Immunology & Microbiology, University of Copenhagen, DK-2200 Copenhagen, Denmark
- Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, Singapore
| | - Niels Høiby
- Department of Clinical Microbiology, Rigshospitalet, DK-2100 Copenhagen, Denmark
- Costerton Biofilm Center, Department of International Health, Immunology & Microbiology, University of Copenhagen, DK-2200 Copenhagen, Denmark.
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31
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Zhao ZG, Yan SS, Yu YM, Mi N, Zhang LX, Liu J, Li XL, Liu F, Xu JF, Yang WQ, Li GM. An aqueous extract of Yunnan Baiyao inhibits the quorum-sensing-related virulence of Pseudomonas aeruginosa. J Microbiol 2013; 51:207-12. [PMID: 23625222 DOI: 10.1007/s12275-013-2595-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Accepted: 12/30/2012] [Indexed: 11/29/2022]
Abstract
Yunnan Baiyao is a famous Chinese medicine that has long been directly applied to wounds to reduce bleeding, pain, and swelling without causing infection. However, little is known about its ability to prevent infection. The present study aimed to assess in vitro the anti-virulence activity of an aqueous extract of Yunnan Baiyao (YBX) using Pseudomonas aeruginosa as a pathogenic model. We found that a sub-MIC (2.5 mg/ml) of YBX can efficiently interfere with the quorum-sensing (QS) signaling circuit. Real-time polymerase chain reaction analysis showed that a sub-MIC of YBX down-regulated the transcriptions of lasR, lasI, rhlR, and rhlI, which resulted in global attenuation of QS-regulated virulence activities, such as biofilm formation, and secretion of LasA protease, LasB elastase and pyocyanin. Further, YBX reduced the motility of P. aeruginosa related to QS, and impaired the formation of biofilms. These results suggest that YBX may possess global inhibitory activity against the virulence of P. aeruginosa and that YBX may also exhibit antimicrobial activity in vivo. The present study suggests that Yunnan Baiyao represents a potential source for isolating novel, safe, and efficacious antimicrobial agents.
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Affiliation(s)
- Zu-Guo Zhao
- Department of Microbiology and Immunology, Guangdong Medical College, Zhanjiang 524023, P. R. China
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Abstract
Enzymes achieve their transition states by dynamic conformational searches on the femtosecond to picosecond time scale. Mimics of reactants at enzymatic transition states bind tightly to enzymes by stabilizing the conformation optimized through evolution for transition state formation. Instead of forming the transient transition state geometry, transition state analogues convert the short-lived transition state to a stable thermodynamic state. Enzymatic transition states are understood by combining kinetic isotope effects and computational chemistry. Analogues of the transition state can bind millions of times more tightly than substrates and show promise for drug development for several targets.
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Affiliation(s)
- Vern L Schramm
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx New York 10461, United States.
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Balasubramanian D, Schneper L, Kumari H, Mathee K. A dynamic and intricate regulatory network determines Pseudomonas aeruginosa virulence. Nucleic Acids Res 2012; 41:1-20. [PMID: 23143271 PMCID: PMC3592444 DOI: 10.1093/nar/gks1039] [Citation(s) in RCA: 313] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Pseudomonas aeruginosa is a metabolically versatile bacterium that is found in a wide range of biotic and abiotic habitats. It is a major human opportunistic pathogen causing numerous acute and chronic infections. The critical traits contributing to the pathogenic potential of P. aeruginosa are the production of a myriad of virulence factors, formation of biofilms and antibiotic resistance. Expression of these traits is under stringent regulation, and it responds to largely unidentified environmental signals. This review is focused on providing a global picture of virulence gene regulation in P. aeruginosa. In addition to key regulatory pathways that control the transition from acute to chronic infection phenotypes, some regulators have been identified that modulate multiple virulence mechanisms. Despite of a propensity for chaotic behaviour, no chaotic motifs were readily observed in the P. aeruginosa virulence regulatory network. Having a ‘birds-eye’ view of the regulatory cascades provides the forum opportunities to pose questions, formulate hypotheses and evaluate theories in elucidating P. aeruginosa pathogenesis. Understanding the mechanisms involved in making P. aeruginosa a successful pathogen is essential in helping devise control strategies.
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Affiliation(s)
- Deepak Balasubramanian
- Department of Biological Sciences, College of Arts and Science, Florida International University, Miami, FL 33199, USA
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