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The Rhl Quorum-Sensing System Is at the Top of the Regulatory Hierarchy under Phosphate-Limiting Conditions in Pseudomonas aeruginosa PAO1. J Bacteriol 2021; 203:JB.00475-20. [PMID: 33288622 DOI: 10.1128/jb.00475-20] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 12/02/2020] [Indexed: 12/13/2022] Open
Abstract
Pseudomonas aeruginosa is a major nosocomial pathogen that presents high-level resistance to antibiotics. Its ability to cause infections relies on the production of multiple virulence factors. Quorum sensing (QS) regulates the expression of many of these virulence factors through three QS systems: Las, Rhl, and PQS. The Las system positively regulates the other two systems, so it is at the top of a hierarchized regulation. Nevertheless, clinical and environmental strains that lack a functional Las system have been isolated, and, surprisingly, some of them still have the ability to produce virulence factors and infect animal models, so it has been suggested that the hierarchy is flexible under some conditions or with atypical strains. Here, we analyze the PAO1 type strain and its ΔlasR-derived mutant and report, for the first time, a growth condition (phosphate limitation) where LasR absence has no effect either on virulence factor production or on the gene expression profile, in contrast to a condition of phosphate repletion where the LasR hierarchy is maintained. This work provides evidence on how the QS hierarchy can change from being a strictly LasR-dependent to a LasR-independent RhlR-based hierarchy under phosphate limitation even in the PAO1 type strain.IMPORTANCE Pseudomonas aeruginosa is an important pathogen, considered a priority for the development of new therapeutic strategies. An important approach to fight its infections relies on blocking quorum sensing. The Las system is the main regulator of the quorum-sensing response, so many research efforts aim to block this system to suppress the entire response. In this work, we show that LasR is dispensable in a phosphate-limited environment in the PAO1 type strain, which has been used to define the quorum-sensing response hierarchy, and that under this condition RhlR is at the top of the regulation hierarchy. These results are highly significant, since phosphate limitation represents a similar environment to the one that P. aeruginosa faces when establishing infections.
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Yashkin A, Rayo J, Grimm L, Welch M, Meijler MM. Short-chain reactive probes as tools to unravel the Pseudomonas aeruginosa quorum sensing regulon. Chem Sci 2021; 12:4570-4581. [PMID: 34163722 PMCID: PMC8179429 DOI: 10.1039/d0sc04444j] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Accepted: 01/28/2021] [Indexed: 11/21/2022] Open
Abstract
In recent years, the world has seen a troubling increase in antibiotic resistance among bacterial pathogens. In order to provide alternative strategies to combat bacterial infections, it is crucial deepen our understanding into the mechanisms that pathogens use to thrive in complex environments. Most bacteria use sophisticated chemical communication systems to sense their population density and coordinate gene expression in a collective manner, a process that is termed "quorum sensing" (QS). The human pathogen Pseudomonas aeruginosa uses several small molecules to regulate QS, and one of them is N-butyryl-l-homoserine lactone (C4-HSL). Using an activity-based protein profiling (ABPP) strategy, we designed biomimetic probes with a photoreactive group and a 'click' tag as an analytical handle. Using these probes, we have identified previously uncharacterized proteins that are part of the P. aeruginosa QS network, and we uncovered an additional role for this natural autoinducer in the virulence regulon of P. aeruginosa, through its interaction with PhzB1/2 that results in inhibition of pyocyanin production.
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Affiliation(s)
- Alex Yashkin
- Dept. of Chemistry, The National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev Be'er Sheva 8410501 Israel
| | - Josep Rayo
- Dept. of Chemistry, The National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev Be'er Sheva 8410501 Israel
| | - Larson Grimm
- Dept. of Biochemistry, University of Cambridge UK
| | - Martin Welch
- Dept. of Biochemistry, University of Cambridge UK
| | - Michael M Meijler
- Dept. of Chemistry, The National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev Be'er Sheva 8410501 Israel
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Sodium Salicylate Influences the Pseudomonas aeruginosa Biofilm Structure and Susceptibility Towards Silver. Int J Mol Sci 2021; 22:ijms22031060. [PMID: 33494399 PMCID: PMC7865925 DOI: 10.3390/ijms22031060] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 01/12/2021] [Accepted: 01/19/2021] [Indexed: 01/30/2023] Open
Abstract
Hard-to-heal wounds are typically infected with biofilm-producing microorganisms, such as Pseudomonas aeruginosa, which strongly contribute to delayed healing. Due to the global challenge of antimicrobial resistance, alternative treatment strategies are needed. Here, we investigated whether inhibition of quorum sensing (QS) by sodium salicylate in different P. aeruginosa strains (QS-competent, QS-mutant, and chronic wound strains) influences biofilm formation and tolerance to silver. Biofilm formation was evaluated in simulated serum-containing wound fluid in the presence or absence of sodium salicylate (NaSa). Biofilms were established using a 3D collagen-based biofilm model, collagen coated glass, and the Calgary biofilm device. Furthermore, the susceptibility of 48-h-old biofilms formed by laboratory and clinical strains in the presence or absence of NaSa towards silver was evaluated by assessing cell viability. Biofilms formed in the presence of NaSa were more susceptible to silver and contained reduced levels of virulence factors associated with biofilm development than those formed in the absence of NaSa. Biofilm aggregates formed by the wild-type but not the QS mutant strain, were smaller and less heterogenous in size when grown in cultures with NaSa compared to control. These data suggest that NaSa, via a reduction of cell aggregation in biofilms, allows the antiseptic to become more readily available to cells.
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Baldelli V, D’Angelo F, Pavoncello V, Fiscarelli EV, Visca P, Rampioni G, Leoni L. Identification of FDA-approved antivirulence drugs targeting the Pseudomonas aeruginosa quorum sensing effector protein PqsE. Virulence 2020; 11:652-668. [PMID: 32423284 PMCID: PMC7549961 DOI: 10.1080/21505594.2020.1770508] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 04/03/2020] [Accepted: 05/05/2020] [Indexed: 12/13/2022] Open
Abstract
The ability of the bacterial pathogen Pseudomonas aeruginosa to cause both chronic and acute infections mainly relies on its capacity to finely modulate the expression of virulence factors through a complex network of regulatory circuits, including the pqs quorum sensing (QS) system. While in most QS systems the signal molecule/receptor complexes act as global regulators that modulate the expression of QS-controlled genes, the main effector protein of the pqs system is PqsE. This protein is involved in the synthesis of the QS signal molecules 2-alkyl-4(1H)-quinolones (AQs), but it also modulates the expression of genes involved in virulence factors production and biofilm formation via AQ-independent pathway(s). P. aeruginosa pqsE mutants disclose attenuated virulence in plant and animal infection models, hence PqsE is considered a good target for the development of antivirulence drugs against P. aeruginosa. In this study, the negative regulation exerted by PqsE on its own transcription has been exploited to develop a screening system for the identification of PqsE inhibitors in a library of FDA-approved drugs. This led to the identification of nitrofurazone and erythromycin estolate, two antibiotic compounds that reduce the expression of PqsE-dependent virulence traits and biofilm formation in the model strain P. aeruginosa PAO1 at concentrations far below those affecting the bacterial growth rate. Notably, both drugs reduce the production of the PqsE-controlled virulence factor pyocyanin also in P. aeruginosa strains isolated from cystic fibrosis patients, and do not antagonize the activity of antibiotics commonly used to treat P. aeruginosa infection.
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Affiliation(s)
| | | | | | | | - Paolo Visca
- Department of Science, University Roma Tre, Rome, Italy
| | | | - Livia Leoni
- Department of Science, University Roma Tre, Rome, Italy
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Beasley KL, Cristy SA, Elmassry MM, Dzvova N, Colmer-Hamood JA, Hamood AN. During bacteremia, Pseudomonas aeruginosa PAO1 adapts by altering the expression of numerous virulence genes including those involved in quorum sensing. PLoS One 2020; 15:e0240351. [PMID: 33057423 PMCID: PMC7561203 DOI: 10.1371/journal.pone.0240351] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 09/24/2020] [Indexed: 12/17/2022] Open
Abstract
Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen that produces numerous virulence factors and causes serious infections in trauma patients and patients with severe burns. We previously showed that the growth of P. aeruginosa in blood from severely burned or trauma patients altered the expression of numerous genes. However, the specific influence of whole blood from healthy volunteers on P. aeruginosa gene expression is not known. Transcriptome analysis of P. aeruginosa grown for 4 h in blood from healthy volunteers compared to that when grown in laboratory medium revealed that the expression of 1085 genes was significantly altered. Quorum sensing (QS), QS-related, and pyochelin synthesis genes were downregulated, while genes of the type III secretion system and those for pyoverdine synthesis were upregulated. The observed effect on the QS and QS-related genes was shown to reside within serum fraction: growth of PAO1 in the presence of 10% human serum from healthy volunteers significantly reduced the expression of QS and QS-regulated genes at 2 and 4 h of growth but significantly enhanced their expression at 8 h. Additionally, the production of QS-regulated virulence factors, including LasA and pyocyanin, was also influenced by the presence of human serum. Serum fractionation experiments revealed that part of the observed effect resides within the serum fraction containing <10-kDa proteins. Growth in serum reduced the production of many PAO1 outer membrane proteins but enhanced the production of others including OprF, a protein previously shown to play a role in the regulation of QS gene expression. These results suggest that factor(s) within human serum: 1) impact P. aeruginosa pathogenesis by influencing the expression of different genes; 2) differentially regulate the expression of QS and QS-related genes in a growth phase- or time-dependent mechanism; and 3) manipulate the production of P. aeruginosa outer membrane proteins.
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Affiliation(s)
- Kellsie L. Beasley
- Department of Immunology and Molecular Microbiology, Texas Tech University Health Sciences Center, Lubbock, Texas, Untied States of America
| | - Shane A. Cristy
- Honors College, Texas Tech University, Lubbock, Texas, Untied States of America
| | - Moamen M. Elmassry
- Department of Biological Sciences, Texas Tech University, Lubbock, Texas, Untied States of America
| | - Nyaradzo Dzvova
- Department of Immunology and Molecular Microbiology, Texas Tech University Health Sciences Center, Lubbock, Texas, Untied States of America
| | - Jane A. Colmer-Hamood
- Department of Immunology and Molecular Microbiology, Texas Tech University Health Sciences Center, Lubbock, Texas, Untied States of America
- Department of Medical Education, Texas Tech University Health Sciences Center, Lubbock, Texas, Untied States of America
| | - Abdul N. Hamood
- Department of Immunology and Molecular Microbiology, Texas Tech University Health Sciences Center, Lubbock, Texas, Untied States of America
- Department of Surgery, Texas Tech University Health Sciences Center, Lubbock, Texas, Untied States of America
- * E-mail:
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Transcriptomic determinants of the response of ST-111 Pseudomonas aeruginosa AG1 to ciprofloxacin identified by a top-down systems biology approach. Sci Rep 2020; 10:13717. [PMID: 32792590 PMCID: PMC7427096 DOI: 10.1038/s41598-020-70581-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 06/25/2020] [Indexed: 12/13/2022] Open
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen that thrives in diverse environments and causes a variety of human infections. Pseudomonas aeruginosa AG1 (PaeAG1) is a high-risk sequence type 111 (ST-111) strain isolated from a Costa Rican hospital in 2010. PaeAG1 has both blaVIM-2 and blaIMP-18 genes encoding for metallo-β-lactamases, and it is resistant to β-lactams (including carbapenems), aminoglycosides, and fluoroquinolones. Ciprofloxacin (CIP) is an antibiotic commonly used to treat P. aeruginosa infections, and it is known to produce DNA damage, triggering a complex molecular response. In order to evaluate the effects of a sub-inhibitory CIP concentration on PaeAG1, growth curves using increasing CIP concentrations were compared. We then measured gene expression using RNA-Seq at three time points (0, 2.5 and 5 h) after CIP exposure to identify the transcriptomic determinants of the response (i.e. hub genes, gene clusters and enriched pathways). Changes in expression were determined using differential expression analysis and network analysis using a top–down systems biology approach. A hybrid model using database-based and co-expression analysis approaches was implemented to predict gene–gene interactions. We observed a reduction of the growth curve rate as the sub-inhibitory CIP concentrations were increased. In the transcriptomic analysis, we detected that over time CIP treatment resulted in the differential expression of 518 genes, showing a complex impact at the molecular level. The transcriptomic determinants were 14 hub genes, multiple gene clusters at different levels (associated to hub genes or as co-expression modules) and 15 enriched pathways. Down-regulation of genes implicated in several metabolism pathways, virulence elements and ribosomal activity was observed. In contrast, amino acid catabolism, RpoS factor, proteases, and phenazines genes were up-regulated. Remarkably, > 80 resident-phage genes were up-regulated after CIP treatment, which was validated at phenomic level using a phage plaque assay. Thus, reduction of the growth curve rate and increasing phage induction was evidenced as the CIP concentrations were increased. In summary, transcriptomic and network analyses, as well as the growth curves and phage plaque assays provide evidence that PaeAG1 presents a complex, concentration-dependent response to sub-inhibitory CIP exposure, showing pleiotropic effects at the systems level. Manipulation of these determinants, such as phage genes, could be used to gain more insights about the regulation of responses in PaeAG1 as well as the identification of possible therapeutic targets. To our knowledge, this is the first report of the transcriptomic analysis of CIP response in a ST-111 high-risk P. aeruginosa strain, in particular using a top-down systems biology approach.
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Pip serves as an intermediate in RpoS-modulated phz2 expression and pyocyanin production in Pseudomonas aeruginosa. Microb Pathog 2020; 147:104409. [PMID: 32707314 DOI: 10.1016/j.micpath.2020.104409] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 07/17/2020] [Accepted: 07/17/2020] [Indexed: 11/22/2022]
Abstract
Pyocyanin, a main virulence factor that is produced by Pseudomonas aeruginosa, plays an important role in pathogen-host interaction during infection. Two copies of phenazine-biosynthetic operons on genome, phz1 (phzA1B1C1D1E1F1G1) and phz2 (phzA2B2C2D2E2F2G2), contribute to phenazine biosynthesis. In our previous study, we found that RpoS positively regulates expression of the phz2 operon and pyocyanin biosynthesis in P. aeruginosa PAO1. In this work, when a TetR-family regulator gene, pip, was knocked out, we found that pyocyanin production was dramatically reduced, indicating that Pip positively regulates pyocyanin biosynthesis. With further phenazines quantification and β-galactosidase assay, we confirmed that Pip positively regulates phz2 expression, but does not regulate phz1 expression. In addition, while the rpoS gene was deleted, expression of pip was down-regulated. Expression of rpoS in the wild-type PAO1 strain, however, was similar to that in the Pip-deficient mutant PAΔpip, suggesting that expression of pip could positively be regulated by RpoS, whereas rpoS could not be regulated by Pip. Taken together, we drew a conclusion that Pip might serve as an intermediate in RpoS-modulated expression of the phz2 operon and pyocyanin biosynthesis in P. aeruginosa.
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Dong L, Pang J, Wang X, Zhang Y, Li G, Hu X, Yang X, Lu CD, Li C, You X. Mechanism of pyocyanin abolishment caused by mvaT mvaU double knockout in Pseudomonas aeruginosa PAO1. Virulence 2020; 11:57-67. [PMID: 31885331 PMCID: PMC6961724 DOI: 10.1080/21505594.2019.1708052] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
MvaT and MvaU are global transcriptional regulators belonging to the H-NS family, and pyocyanin is an important virulence factor produced by Pseudomonas aeruginosa. mvaT mvaU double knockout mutant of P. aeruginosa PAO1 demonstrated pyocyanin abolishment in the previous study. Here, we further explored the mechanism. Two main directions were studied: pyocyanin biosynthesis pathway and QS system. The effect on the expression of the pyocyanin biosynthesis genes was evaluated by promoter strength determination and Real-Time PCR assay, and significant changes leading to low pyocyanin production were found. The effect on the QS system was studied by signal molecule quantification using LC-MS/MS and related gene expression measurements using Real-Time PCR. In mvaT mvaU double knockout, the production of 3-oxo-C12-HSL obviously increased, while those of C4-HSL and PQS obviously decreased, and the changes can be recovered by mvaT or mvaU complementation. The expressions of transcriptional activator genes binding with QS system signal molecules were all decreased, resulting in decreased formation of signal-transcriptional activator complexes. And the decreased expression of rhlR and pqsE also led to the lower expression of phzA1 and phzA2. Further exploration found that QS system downregulation may be related to QsrO, a QS system repressor, which was highly upregulated with mvaT mvaU double knockout. Hence, the synthesis of pyocyanin was suffocated and the biofilm formation ability was decreased. These results were also confirmed by transcriptome analysis, which demonstrated similar gene expression changes of the aforementioned genes together with decreased expression of other virulence factor genes regulated by QS system.
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Affiliation(s)
- Limin Dong
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Jing Pang
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Xiukun Wang
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Youwen Zhang
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Guoqing Li
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Xinxin Hu
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Xinyi Yang
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Chung-Dar Lu
- Department of Biomedical and Nutritional Sciences, University of Massachusetts at Lowell, Lowell, MA, USA
| | - Congran Li
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Xuefu You
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
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Chatterjee P, Sass G, Swietnicki W, Stevens DA. Review of Potential Pseudomonas Weaponry, Relevant to the Pseudomonas-Aspergillus Interplay, for the Mycology Community. J Fungi (Basel) 2020; 6:jof6020081. [PMID: 32517271 PMCID: PMC7345761 DOI: 10.3390/jof6020081] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 06/03/2020] [Accepted: 06/03/2020] [Indexed: 12/15/2022] Open
Abstract
Pseudomonas aeruginosa is one of the most prominent opportunistic bacteria in airways of cystic fibrosis patients and in immunocompromised patients. These bacteria share the same polymicrobial niche with other microbes, such as the opportunistic fungus Aspergillus fumigatus. Their inter-kingdom interactions and diverse exchange of secreted metabolites are responsible for how they both fare in competition for ecological niches. The outcomes of their contests likely determine persistent damage and degeneration of lung function. With a myriad of virulence factors and metabolites of promising antifungal activity, P. aeruginosa products or their derivatives may prove useful in prophylaxis and therapy against A. fumigatus. Quorum sensing underlies the primary virulence strategy of P. aeruginosa, which serves as cell–cell communication and ultimately leads to the production of multiple virulence factors. Understanding the quorum-sensing-related pathogenic mechanisms of P. aeruginosa is a first step for understanding intermicrobial competition. In this review, we provide a basic overview of some of the central virulence factors of P. aeruginosa that are regulated by quorum-sensing response pathways and briefly discuss the hitherto known antifungal properties of these virulence factors. This review also addresses the role of the bacterial secretion machinery regarding virulence factor secretion and maintenance of cell–cell communication.
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Affiliation(s)
- Paulami Chatterjee
- California Institute for Medical Research, San Jose, CA 95128, USA; (P.C.); (G.S.)
| | - Gabriele Sass
- California Institute for Medical Research, San Jose, CA 95128, USA; (P.C.); (G.S.)
| | - Wieslaw Swietnicki
- Department of Immunology of Infectious Diseases, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, 50-114 Wroclaw, Poland;
| | - David A. Stevens
- California Institute for Medical Research, San Jose, CA 95128, USA; (P.C.); (G.S.)
- Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
- Correspondence: ; Tel.: +1-408-998-4554
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Sarkar S. Release mechanisms and molecular interactions of Pseudomonas aeruginosa extracellular DNA. Appl Microbiol Biotechnol 2020; 104:6549-6564. [PMID: 32500267 DOI: 10.1007/s00253-020-10687-9] [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: 03/04/2020] [Revised: 05/10/2020] [Accepted: 05/17/2020] [Indexed: 12/18/2022]
Abstract
Pseudomonas aeruginosa infection is a significant threat for clinicians. Increasing incidents of resistant biofilm infection result in high mortality rates worldwide. There is a considerable current interest in the field of extracellular DNA (eDNA)-mediated P. aeruginosa biofilm formation. eDNA acts as a glue to make biofilm more stable. This review focuses on the diverse mechanisms and factors, which enhance the eDNA release into the extracellular milieu. Furthermore, eDNA-mediated molecular interactions within the biofilm are emphasized. In addition, drug resistance mechanisms due to the versatility of eDNA are discussed. Spatial physiological diversity is expected due to different metabolic activity of bacterial subpopulation present in P. aeruginosa biofilm layers. In P. aeruginosa, eDNA release is accomplished by cell lysis and OMVs (outer membrane vesicles). eDNA release is a spontaneous and multifactorial process, which may be accomplished by PQS, pyocyanin, and lambda prophage induction. Hydrogen peroxide and pyocin trigger cell death, which may facilitate eDNA release. Lung mucosa of cystic fibrosis patients is enriched with eDNA, which acidifies biofilm and develops P. aeruginosa resistance to aminoglycosides. Further studies on spatial and molecular characterization of bacterial subpopulation in biofilm will shed light on eDNA-biofilm interaction more precisely.Key Points• Extracellular DNA (eDNA) is a key component of Pseudomonas aeruginosa biofilm.• P. aeruginosa eDNA acts as a glue to make biofilm more stronger.• Bacterial cell death or lysis may be the potential way to release P. aeruginosa eDNA into extracellular milieu.• P. aeruginosa eDNA contributes to develop resistance to antimicrobials.
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Affiliation(s)
- Subendu Sarkar
- Department of Surgery, University School of Medicine, Indiana University, Indianapolis, IN, 46202, USA. .,Department of Surgery, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, 43210, USA.
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Abstract
Pseudomonas aeruginosa is a versatile bacterium found in various environments. It can cause severe infections in immunocompromised patients and naturally resists many antibiotics. The World Health Organization listed it among the top priority pathogens for research and development of new antimicrobial compounds. Quorum sensing (QS) is a cell-cell communication mechanism, which is important for P. aeruginosa adaptation and pathogenesis. Here, we validate the central role of the PqsE protein in QS particularly by its impact on the regulator RhlR. This study challenges the traditional dogmas of QS regulation in P. aeruginosa and ties loose ends in our understanding of the traditional QS circuit by confirming RhlR to be the main QS regulator in P. aeruginosa. PqsE could represent an ideal target for the development of new control methods against the virulence of P. aeruginosa. This is especially important when considering that LasR-defective mutants frequently arise, e.g., in chronic infections. The bacterium Pseudomonas aeruginosa has emerged as a central threat in health care settings and can cause a large variety of infections. It expresses an arsenal of virulence factors and a diversity of survival functions, many of which are finely and tightly regulated by an intricate circuitry of three quorum sensing (QS) systems. The las system is considered at the top of the QS hierarchy and activates the rhl and pqs systems. It is composed of the LasR transcriptional regulator and the LasI autoinducer synthase, which produces 3-oxo-C12-homoserine lactone (3-oxo-C12-HSL), the ligand of LasR. RhlR is the transcriptional regulator for the rhl system and is associated with RhlI, which produces its cognate autoinducer C4-HSL. The third QS system is composed of the pqsABCDE operon and the MvfR (PqsR) regulator. PqsABCD synthetize 4-hydroxy-2-alkylquinolines (HAQs), which include ligands activating MvfR. PqsE is not required for HAQ production and instead is associated with the expression of genes controlled by the rhl system. While RhlR is often considered the main regulator of rhlI, we confirmed that LasR is in fact the principal regulator of C4-HSL production and that RhlR regulates rhlI and production of C4-HSL essentially only in the absence of LasR by using liquid chromatography-mass spectrometry quantifications and gene expression reporters. Investigating the expression of RhlR targets also clarified that activation of RhlR-dependent QS relies on PqsE, especially when LasR is not functional. This work positions RhlR as the key QS regulator and points to PqsE as an essential effector for full activation of this regulation. IMPORTANCEPseudomonas aeruginosa is a versatile bacterium found in various environments. It can cause severe infections in immunocompromised patients and naturally resists many antibiotics. The World Health Organization listed it among the top priority pathogens for research and development of new antimicrobial compounds. Quorum sensing (QS) is a cell-cell communication mechanism, which is important for P. aeruginosa adaptation and pathogenesis. Here, we validate the central role of the PqsE protein in QS particularly by its impact on the regulator RhlR. This study challenges the traditional dogmas of QS regulation in P. aeruginosa and ties loose ends in our understanding of the traditional QS circuit by confirming RhlR to be the main QS regulator in P. aeruginosa. PqsE could represent an ideal target for the development of new control methods against the virulence of P. aeruginosa. This is especially important when considering that LasR-defective mutants frequently arise, e.g., in chronic infections.
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Miller C, Gilmore J. Detection of Quorum-Sensing Molecules for Pathogenic Molecules Using Cell-Based and Cell-Free Biosensors. Antibiotics (Basel) 2020; 9:antibiotics9050259. [PMID: 32429345 PMCID: PMC7277912 DOI: 10.3390/antibiotics9050259] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 05/13/2020] [Accepted: 05/14/2020] [Indexed: 11/18/2022] Open
Abstract
Since the discovery and subsequent use of penicillin, antibiotics have been used to treat most bacterial infections in the U.S. Over time, the repeated prescription of many antibiotics has given rise to many antibiotic-resistant microbes. A bacterial strain becomes resistant by horizontal gene transfer, where surviving microbes acquire genetic material or DNA fragments from adjacent bacteria that encode for resistance. In order to avoid significant bacterial resistance, novel and target therapeutics are needed. Further advancement of diagnostic technologies could be used to develop novel treatment strategies. The use of biosensors to detect quorum-sensing signaling molecules has the potential to provide timely diagnostic information toward mitigating the multidrug-resistant bacteria epidemic. Resistance and pathogenesis are controlled by quorum-sensing (QS) circuits. QS systems secrete or passively release signaling molecules when the bacterial concentration reaches a certain threshold. Signaling molecules give an early indication of virulence. Detection of these compounds in vitro or in vivo can be used to identify the onset of infection. Whole-cell and cell-free biosensors have been developed to detect quorum-sensing signaling molecules. This review will give an overview of quorum networks in the most common pathogens found in chronic and acute infections. Additionally, the current state of research surrounding the detection of quorum-sensing molecules will be reviewed. Followed by a discussion of future works toward the advancement of technologies to quantify quorum signaling molecules in chronic and acute infections.
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Soukarieh F, Liu R, Romero M, Roberston SN, Richardson W, Lucanto S, Oton EV, Qudus NR, Mashabi A, Grossman S, Ali S, Sou T, Kukavica-Ibrulj I, Levesque RC, Bergström CAS, Halliday N, Mistry SN, Emsley J, Heeb S, Williams P, Cámara M, Stocks MJ. Hit Identification of New Potent PqsR Antagonists as Inhibitors of Quorum Sensing in Planktonic and Biofilm Grown Pseudomonas aeruginosa. Front Chem 2020; 8:204. [PMID: 32432073 PMCID: PMC7213079 DOI: 10.3389/fchem.2020.00204] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 03/04/2020] [Indexed: 12/11/2022] Open
Abstract
Current treatments for Pseudomonas aeruginosa infections are becoming less effective because of the increasing rates of multi-antibiotic resistance. Pharmacological targeting of virulence through inhibition of quorum sensing (QS) dependent virulence gene regulation has considerable therapeutic potential. In P. aeruginosa, the pqs QS system regulates the production of multiple virulence factors as well as biofilm maturation and is a promising approach for developing antimicrobial adjuvants for combatting drug resistance. In this work, we report the hit optimisation for a series of potent novel inhibitors of PqsR, a key regulator of the pqs system, bearing a 2-((5-methyl-5H-[1,2,4]triazino[5,6-b]indol-3-yl)thio) acetamide scaffold. The initial hit compound 7 (PAO1-L IC50 0.98 ± 0.02 μM, PA14 inactive at 10 μM) was obtained through a virtual screening campaign performed on the PqsR ligand binding domain using the University of Nottingham Managed Chemical Compound Collection. Hit optimisation gave compounds with enhanced potency against strains PAO1-L and PA14, evaluated using P. aeruginosa pqs-based QS bioreporter assays. Compound 40 (PAO1-L IC50 0.25 ± 0.12 μM, PA14 IC50 0.34 ± 0.03 μM) is one of the most potent PqsR antagonists reported showing significant inhibition of P. aeruginosa pyocyanin production and pqs system signaling in both planktonic cultures and biofilms. The co-crystal structure of 40 with the PqsR ligand binding domain revealed the specific binding interactions occurring between inhibitor and this key regulatory protein.
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Affiliation(s)
- Fadi Soukarieh
- School of Life Sciences, University of Nottingham Biodiscovery Institute, University of Nottingham, Nottingham, United Kingdom.,The National Biofilms Innovation Centre, University of Nottingham, Nottingham, United Kingdom
| | - Ruiling Liu
- School of Pharmacy, University of Nottingham Biodiscovery Institute, University of Nottingham, Nottingham, United Kingdom
| | - Manuel Romero
- School of Life Sciences, University of Nottingham Biodiscovery Institute, University of Nottingham, Nottingham, United Kingdom.,The National Biofilms Innovation Centre, University of Nottingham, Nottingham, United Kingdom
| | - Shaun N Roberston
- School of Life Sciences, University of Nottingham Biodiscovery Institute, University of Nottingham, Nottingham, United Kingdom.,The National Biofilms Innovation Centre, University of Nottingham, Nottingham, United Kingdom
| | - William Richardson
- School of Pharmacy, University of Nottingham Biodiscovery Institute, University of Nottingham, Nottingham, United Kingdom
| | - Simone Lucanto
- School of Life Sciences, University of Nottingham Biodiscovery Institute, University of Nottingham, Nottingham, United Kingdom.,The National Biofilms Innovation Centre, University of Nottingham, Nottingham, United Kingdom
| | - Eduard Vico Oton
- School of Life Sciences, University of Nottingham Biodiscovery Institute, University of Nottingham, Nottingham, United Kingdom
| | - Naim Ruhul Qudus
- School of Life Sciences, University of Nottingham Biodiscovery Institute, University of Nottingham, Nottingham, United Kingdom
| | - Alaa Mashabi
- School of Pharmacy, University of Nottingham Biodiscovery Institute, University of Nottingham, Nottingham, United Kingdom
| | - Scott Grossman
- School of Pharmacy, University of Nottingham Biodiscovery Institute, University of Nottingham, Nottingham, United Kingdom
| | - Sadiqur Ali
- School of Life Sciences, University of Nottingham Biodiscovery Institute, University of Nottingham, Nottingham, United Kingdom
| | - Tomás Sou
- Drug Delivery Group, Department of Pharmacy, Uppsala University, Uppsala, Sweden.,Pharmacometrics Group, Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | - Irena Kukavica-Ibrulj
- Institut de Biologie Intégrative et des Systèmes, Université Laval, Quebec City, QC, Canada
| | - Roger C Levesque
- Institut de Biologie Intégrative et des Systèmes, Université Laval, Quebec City, QC, Canada
| | - Christel A S Bergström
- Drug Delivery Group, Department of Pharmacy, Uppsala University, Uppsala, Sweden.,The Swedish Drug Delivery Center, Department of Pharmacy, Uppsala University, Uppsala, Sweden
| | - Nigel Halliday
- School of Life Sciences, University of Nottingham Biodiscovery Institute, University of Nottingham, Nottingham, United Kingdom
| | - Shailesh N Mistry
- School of Pharmacy, University of Nottingham Biodiscovery Institute, University of Nottingham, Nottingham, United Kingdom
| | - Jonas Emsley
- The National Biofilms Innovation Centre, University of Nottingham, Nottingham, United Kingdom.,School of Pharmacy, University of Nottingham Biodiscovery Institute, University of Nottingham, Nottingham, United Kingdom
| | - Stephan Heeb
- School of Life Sciences, University of Nottingham Biodiscovery Institute, University of Nottingham, Nottingham, United Kingdom
| | - Paul Williams
- School of Life Sciences, University of Nottingham Biodiscovery Institute, University of Nottingham, Nottingham, United Kingdom.,The National Biofilms Innovation Centre, University of Nottingham, Nottingham, United Kingdom
| | - Miguel Cámara
- School of Life Sciences, University of Nottingham Biodiscovery Institute, University of Nottingham, Nottingham, United Kingdom.,The National Biofilms Innovation Centre, University of Nottingham, Nottingham, United Kingdom
| | - Michael J Stocks
- The National Biofilms Innovation Centre, University of Nottingham, Nottingham, United Kingdom.,School of Pharmacy, University of Nottingham Biodiscovery Institute, University of Nottingham, Nottingham, United Kingdom
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64
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Mukherji R, Zhang S, Chowdhury S, Stallforth P. Chimeric LuxR Transcription Factors Rewire Natural Product Regulation. Angew Chem Int Ed Engl 2020; 59:6192-6195. [PMID: 31943579 PMCID: PMC7187462 DOI: 10.1002/anie.201914449] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 12/12/2019] [Indexed: 01/17/2023]
Abstract
LuxR-type transcriptional activator proteins frequently regulate the expression of biosynthetic gene clusters (BGCs). With only a fraction of bacterial BGCs being expressed under standard culturing conditions, modulation of LuxRs would provide a powerful approach to activate silent clusters. We show that by exploiting the modular nature of LuxR proteins, it is possible to construct functional chimeric LuxRs, which enables both the rewiring of quorum sensing systems and the activation of silent BGCs. Importantly, our strategy allowed us to identify the novel natural product pseudomonol from a bacterium of the genus Pseudomonas.
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Affiliation(s)
- Ruchira Mukherji
- Independent Junior Research Group Chemistry of Microbial CommunicationLeibniz Institute for Natural Product Research and Infection BiologyHans Knöll Institute (HKI)Beutenbergstrasse 11a07745JenaGermany
| | - Shuaibing Zhang
- Independent Junior Research Group Chemistry of Microbial CommunicationLeibniz Institute for Natural Product Research and Infection BiologyHans Knöll Institute (HKI)Beutenbergstrasse 11a07745JenaGermany
| | - Somak Chowdhury
- Independent Junior Research Group Chemistry of Microbial CommunicationLeibniz Institute for Natural Product Research and Infection BiologyHans Knöll Institute (HKI)Beutenbergstrasse 11a07745JenaGermany
| | - Pierre Stallforth
- Independent Junior Research Group Chemistry of Microbial CommunicationLeibniz Institute for Natural Product Research and Infection BiologyHans Knöll Institute (HKI)Beutenbergstrasse 11a07745JenaGermany
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65
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Mukherji R, Zhang S, Chowdhury S, Stallforth P. Chimeric LuxR Transcription Factors Rewire Natural Product Regulation. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201914449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Ruchira Mukherji
- Independent Junior Research Group Chemistry of Microbial CommunicationLeibniz Institute for Natural Product Research and Infection BiologyHans Knöll Institute (HKI) Beutenbergstrasse 11a 07745 Jena Germany
| | - Shuaibing Zhang
- Independent Junior Research Group Chemistry of Microbial CommunicationLeibniz Institute for Natural Product Research and Infection BiologyHans Knöll Institute (HKI) Beutenbergstrasse 11a 07745 Jena Germany
| | - Somak Chowdhury
- Independent Junior Research Group Chemistry of Microbial CommunicationLeibniz Institute for Natural Product Research and Infection BiologyHans Knöll Institute (HKI) Beutenbergstrasse 11a 07745 Jena Germany
| | - Pierre Stallforth
- Independent Junior Research Group Chemistry of Microbial CommunicationLeibniz Institute for Natural Product Research and Infection BiologyHans Knöll Institute (HKI) Beutenbergstrasse 11a 07745 Jena Germany
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66
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Wang K, Kai L, Zhang K, Hao M, Yu Y, Xu X, Yu Z, Chen L, Chi X, Ge Y. Overexpression of phzM contributes to much more production of pyocyanin converted from phenazine-1-carboxylic acid in the absence of RpoS in Pseudomonas aeruginosa. Arch Microbiol 2020; 202:1507-1515. [PMID: 32222778 DOI: 10.1007/s00203-020-01837-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 01/15/2020] [Accepted: 02/14/2020] [Indexed: 11/29/2022]
Abstract
Pyocyanin produced by Pseudomonas aeruginosa is a key virulence factor that often causes heavy damages to airway and lung in patients. Conversion of phenazine-1-carboxylic acid to pyocyanin involves an extrametabolic pathway that contains two enzymes encoded, respectively, by phzM and phzS. In this study, with construction of the rpoS-deficient mutant, we first found that although phenazine production increased, pyocyanin produced in the mutant YTΔrpoS was fourfold much higher than that in the wild-type strain YT. To investigate this issue, we constructed phzM-lacZ fusion on a vector and on the chromosome. By quantifying β-galactosidase activities, we confirmed that expression of the phzM was up-regulated when the rpoS gene was inactivated. However, no changes occurred in the expression of phzS and phzH when the rpoS was knocked out. Taken together, overproduction of the SAM-dependent methyltransferase (PhzM) might contribute to the increased pyocyanin in the absence of RpoS in P. aeruginosa.
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Affiliation(s)
- Kewen Wang
- Department of Applied and Environmental Microbiology, Ludong University, Yantai, 264000, China
| | - Le Kai
- Department of Applied and Environmental Microbiology, Ludong University, Yantai, 264000, China
| | - Kailu Zhang
- Department of Applied and Environmental Microbiology, Ludong University, Yantai, 264000, China
| | - Mengyue Hao
- Department of Applied and Environmental Microbiology, Ludong University, Yantai, 264000, China
| | - Yanjie Yu
- Department of Applied and Environmental Microbiology, Ludong University, Yantai, 264000, China
| | - Xinyu Xu
- Department of Applied and Environmental Microbiology, Ludong University, Yantai, 264000, China
| | - Zhifen Yu
- Affiliated Hospital, Ludong University, Yantai, 264025, China
| | - Lijuan Chen
- Affiliated Hospital, Ludong University, Yantai, 264025, China
| | - Xiaoyan Chi
- Department of Applied and Environmental Microbiology, Ludong University, Yantai, 264000, China.
| | - Yihe Ge
- Department of Applied and Environmental Microbiology, Ludong University, Yantai, 264000, China. .,Affiliated Hospital, Ludong University, Yantai, 264025, China.
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67
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Sun S, Tan LTH, Fang YL, Jin ZJ, Zhou L, Goh BH, Lee LH, Zhou J, He YW. Overexpression of oxyR Increases Phenazine-1-Carboxylic Acid Biosynthesis via Small RNA phrS in the Rhizobacterium Strain Pseudomonas PA1201. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2020; 33:488-498. [PMID: 31710580 DOI: 10.1094/mpmi-09-19-0264-r] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Phenazine-1-carboxylic acid (PCA) is the primary active component in the newly registered, commercial biopesticide Shenqinmycin and is produced during fermentation by the engineered rhizobacterium strain Pseudomonas PA1201. Both phz1 and phz2 gene clusters contribute to PCA biosynthesis. In this study, we evaluated the role of OxyR in the regulation of PCA biosynthesis in PA1201. We first showed a functional link between oxyR expression and PCA biosynthesis. Deletion of oxyR and overexpression of oxyR both increase PCA biosynthesis. The molecular mechanisms underlying OxyR regulation of PCA production were investigated using several approaches. OxyR acts divergently in phz1 and phz2. Overexpression of oxyR activated the expression of phz1 and phz1-dependent PCA production. However, overexpression of oxyR had little effect on phz2-dependent PCA biosynthesis, while deletion of oxyR promoted phz2-dependent PCA production and exerted a negative effect on phz2 expression. Further, OxyR directly bound to the phz2 promoter region. In addition, the regulation of PCA biosynthesis by OxyR was associated with quorum sensing (QS) systems. Overexpression of OxyR positively regulated pqs QS system. Finally, transcriptomic analysis and subsequent genetic analysis revealed the small RNA phrS plays a key role in OxyR-dependent PCA accumulation. Specifically, OxyR directly binds to the phrS promoter region to positively regulate phrS expression wherein PhrS regulates the PCA positive regulator MvfR in order to control PCA biosynthesis.
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Affiliation(s)
- Shuang Sun
- Shandong Provincial Key Laboratory of Animal Resistance Biology, Institute of Biomedical Sciences, College of Life Sciences, Shandong Normal University, Jinan, China
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Loh Teng-Hern Tan
- Novel Bacteria and Drug Discovery Research Group (NBDD), Microbiome and Bioresource Research Strength, Jeffrey Cheah School of Medicine and Health Science, Monash University Malaysia, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia
| | - Yun-Ling Fang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Zi-Jing Jin
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Lian Zhou
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Bey-Hing Goh
- Biofunctional Molecule Exploratory Research Group (BMEX), School of Pharmacy, Monash University Malaysia
| | - Learn-Han Lee
- Novel Bacteria and Drug Discovery Research Group (NBDD), Microbiome and Bioresource Research Strength, Jeffrey Cheah School of Medicine and Health Science, Monash University Malaysia, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia
| | - Jun Zhou
- Shandong Provincial Key Laboratory of Animal Resistance Biology, Institute of Biomedical Sciences, College of Life Sciences, Shandong Normal University, Jinan, China
| | - Ya-Wen He
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
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68
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Skariyachan S, Gopal D, Kadam SP, Muddebihalkar AG, Uttarkar A, Niranjan V. Carbon fullerene acts as potential lead molecule against prospective molecular targets of biofilm-producing multidrug-resistant Acinetobacter baumanni and Pseudomonas aerugenosa: computational modeling and MD simulation studies. J Biomol Struct Dyn 2020; 39:1121-1137. [PMID: 32036742 DOI: 10.1080/07391102.2020.1726821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
This study aimed to screen putative drug targets associated with biofilm formation of multidrug-resistant Acinetobacter baumannii and Pseudomonas areugenosa and prioritize carbon nano-fullerene as potential lead molecule by structure-based virtual screening. Based on the functional role, 36 and 83 genes that are involved in biofilm formation of A. baumannii and P. areugenosa respectively were selected and metabolic network was computationally constructed. The genes that lack three-dimensional structures were predicted and validated. Carbon nano-fullerene selected as lead molecule and their drug-likeliness and pharmacokinetics properties were computationally predicted. The binding potential of carbon nano-fullerene toward selected drug targets was modeled and compared with the binding of conventional drugs, doripenem, and polymyxin-B with their usual targets. The stabilities of four best-docked complexes were confirmed by molecular dynamic (MD) simulation. This study suggested that selected genes demonstrated relevant interactions in the constructed metabolic pathways. Carbon fullerene exhibited significant binding abilities to most of the prioritized targets in comparison with the binding of last-resort antibiotics and their usual target. The four best ligand-receptor interactions predicted by molecular docking revealed that stability throughout MD simulation. Notably, carbon fullerene exhibited profound binding with outer membrane protein (OmpA) and ribonuclease-HII (rnhB) of A. baumannii and 2-heptyl-4(1H)-quinolone synthase (pqsBC) and chemotaxis protein (wspA) of P. aeruginosa. Thus, the current study suggested that carbon fullerene was probably used as potential lead molecules toward selected targets of A. baumannii and P. aeruginosa and the applied aspects probably scaled up to design promising lead molecules toward these pathogens. Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Sinosh Skariyachan
- Department of Microbiology, St. Pius X College, Rajapuram, Kasaragod, India
| | - Dharshini Gopal
- Department of Biotechnology, Dayananda Sagar College of Engineering, Bengaluru, India
| | - Sanjana Pratab Kadam
- Department of Biotechnology, Dayananda Sagar College of Engineering, Bengaluru, India
| | - Aditi G Muddebihalkar
- Department of Biotechnology, Dayananda Sagar College of Engineering, Bengaluru, India.,Department of Biotechnology, RV College of Engineering, Bengaluru, India
| | - Akshay Uttarkar
- Department of Biotechnology, RV College of Engineering, Bengaluru, India
| | - Vidya Niranjan
- Department of Biotechnology, RV College of Engineering, Bengaluru, India
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69
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Mahan K, Martinmaki R, Larus I, Sikdar R, Dunitz J, Elias M. Effects of Signal Disruption Depends on the Substrate Preference of the Lactonase. Front Microbiol 2020; 10:3003. [PMID: 31993034 PMCID: PMC6971184 DOI: 10.3389/fmicb.2019.03003] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 12/12/2019] [Indexed: 12/19/2022] Open
Abstract
Many bacteria produce and use extracellular signaling molecules such as acyl homoserine lactones (AHLs) to communicate and coordinate behavior in a cell-density dependent manner, via a communication system called quorum sensing (QS). This system regulates behaviors including but not limited to virulence and biofilm formation. We focused on Pseudomonas aeruginosa, a human opportunistic pathogen that is involved in acute and chronic lung infections and which disproportionately affects people with cystic fibrosis. P. aeruginosa infections are becoming increasingly challenging to treat with the spread of antibiotic resistance. Therefore, QS disruption approaches, known as quorum quenching, are appealing due to their potential to control the virulence of resistant strains. Interestingly, P. aeruginosa is known to simultaneously utilize two main QS circuits, one based on C4-AHL, the other with 3-oxo-C12-AHL. Here, we evaluated the effects of signal disruption on 39 cystic fibrosis clinical isolates of P. aeruginosa, including drug resistant strains. We used two enzymes capable of degrading AHLs, known as lactonases, with distinct substrate preference: one degrading 3-oxo-C12-AHL, the other degrading both C4-AHL and 3-oxo-C12-AHL. Two lactonases were used to determine the effects of signal disruption on the clinical isolates, and to evaluate the importance of the QS circuits by measuring effects on virulence factors (elastase, protease, and pyocyanin) and biofilm formation. Signal disruption results in at least one of these factors being inhibited for most isolates (92%). Virulence factor activity or production were inhibited by up to 100% and biofilm was inhibited by an average of 2.3 fold. Remarkably, the treatments led to distinct inhibition profiles of the isolates; the treatment with the lactonase degrading both signaling molecules resulted in a higher fraction of inhibited isolates (77% vs. 67%), and the simultaneous inhibition of more virulence factors per strain (2 vs. 1.5). This finding suggests that the lactonase AHL preference is key to its inhibitory spectrum and is an essential parameter to improve quorum quenching strategies.
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Affiliation(s)
- Kathleen Mahan
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, University of Minnesota, Minneapolis, MN, United States
| | - Ryan Martinmaki
- Department of Biochemistry, Molecular Biology and Biophysics, Biotechnology Institute, University of Minnesota, Saint Paul, MN, United States
| | - Isabel Larus
- Department of Biochemistry, Molecular Biology and Biophysics, Biotechnology Institute, University of Minnesota, Saint Paul, MN, United States
| | - Rakesh Sikdar
- Department of Biochemistry, Molecular Biology and Biophysics, Biotechnology Institute, University of Minnesota, Saint Paul, MN, United States
| | - Jordan Dunitz
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, University of Minnesota, Minneapolis, MN, United States
- Department of Medicine, Minnesota Cystic Fibrosis Center and Adult CF Program, University of Minnesota, Minneapolis, MN, United States
| | - Mikael Elias
- Department of Biochemistry, Molecular Biology and Biophysics, Biotechnology Institute, University of Minnesota, Saint Paul, MN, United States
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70
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Acharya D, Miller I, Cui Y, Braun DR, Berres ME, Styles MJ, Li L, Kwan J, Rajski SR, Blackwell HE, Bugni TS. Omics Technologies to Understand Activation of a Biosynthetic Gene Cluster in Micromonospora sp. WMMB235: Deciphering Keyicin Biosynthesis. ACS Chem Biol 2019; 14:1260-1270. [PMID: 31120241 PMCID: PMC6591704 DOI: 10.1021/acschembio.9b00223] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
![]()
DNA
sequencing of a large collection of bacterial genomes reveals
a wealth of orphan biosynthetic gene clusters (BGCs) with no identifiable
products. BGC silencing, for those orphan clusters that are truly
silent, rather than those whose products have simply evaded detection
and cluster correlation, is postulated to result from transcriptional
inactivation of these clusters under standard laboratory conditions.
Here, we employ a multi-omics approach to demonstrate how interspecies
interactions modulate the keyicin producing kyc cluster
at the transcriptome level in cocultures of kyc-bearing Micromonospora sp. and a Rhodococcus sp.
We further correlate coculture dependent changes in keyicin production
to changes in transcriptomic and proteomic profiles and show that
these changes are attributable to small molecule signaling consistent
with a quorum sensing pathway. In piecing together the various elements
underlying keyicin production in coculture, this study highlights
how omics technologies can expedite future efforts to understand and
exploit silent BGCs.
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Affiliation(s)
- Deepa Acharya
- Pharmaceutical Sciences Division, University of Wisconsin—Madison, Madison, Wisconsin 53705, United States
| | - Ian Miller
- Pharmaceutical Sciences Division, University of Wisconsin—Madison, Madison, Wisconsin 53705, United States
| | - Yusi Cui
- Pharmaceutical Sciences Division, University of Wisconsin—Madison, Madison, Wisconsin 53705, United States
| | - Doug R. Braun
- Pharmaceutical Sciences Division, University of Wisconsin—Madison, Madison, Wisconsin 53705, United States
| | - Mark E. Berres
- Bioinformatics Resource Center, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
| | - Matthew J. Styles
- Department of Chemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
| | - Lingjun Li
- Pharmaceutical Sciences Division, University of Wisconsin—Madison, Madison, Wisconsin 53705, United States
| | - Jason Kwan
- Pharmaceutical Sciences Division, University of Wisconsin—Madison, Madison, Wisconsin 53705, United States
| | - Scott R. Rajski
- Pharmaceutical Sciences Division, University of Wisconsin—Madison, Madison, Wisconsin 53705, United States
| | - Helen E. Blackwell
- Department of Chemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
| | - Tim S. Bugni
- Pharmaceutical Sciences Division, University of Wisconsin—Madison, Madison, Wisconsin 53705, United States
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71
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McCready AR, Paczkowski JE, Cong JP, Bassler BL. An autoinducer-independent RhlR quorum-sensing receptor enables analysis of RhlR regulation. PLoS Pathog 2019; 15:e1007820. [PMID: 31194839 PMCID: PMC6564026 DOI: 10.1371/journal.ppat.1007820] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 05/07/2019] [Indexed: 01/03/2023] Open
Abstract
Quorum sensing is a chemical communication process that bacteria use to coordinate group behaviors. Pseudomonas aeruginosa, an opportunistic pathogen, employs multiple quorum-sensing systems to control behaviors including virulence factor production and biofilm formation. One P. aeruginosa quorum-sensing receptor, called RhlR, binds the cognate autoinducer N-butryl-homoserine lactone (C4HSL), and the RhlR:C4HSL complex activates transcription of target quorum-sensing genes. Here, we use a genetic screen to identify RhlR mutants that function independently of the autoinducer. The RhlR Y64F W68F V133F triple mutant, which we call RhlR*, exhibits ligand-independent activity in vitro and in vivo. RhlR* can drive wildtype biofilm formation and infection in a nematode animal model. The ability of RhlR* to properly regulate quorum-sensing-controlled genes in vivo depends on the quorum-sensing regulator RsaL keeping RhlR* activity in check. RhlR is known to function together with PqsE to control production of the virulence factor called pyocyanin. Likewise, RhlR* requires PqsE for pyocyanin production in planktonic cultures, however, PqsE is dispensable for RhlR*-driven pyocyanin production on surfaces. Finally, wildtype RhlR protein is not sufficiently stabilized by C4HSL to allow purification. However, wildtype RhlR can be stabilized by the synthetic ligand mBTL (meta-bromo-thiolactone) and RhlR* is stable without a ligand. These features enabled purification of the RhlR:mBTL complex and of RhlR* for in vitro examination of their biochemical activities. To our knowledge, this work reports the first RhlR protein purification.
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Affiliation(s)
- Amelia R. McCready
- The Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
| | - Jon E. Paczkowski
- The Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
| | - Jian-Ping Cong
- The Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
- Howard Hughes Medical Institute, Chevy Chase, Maryland, United States of America
| | - Bonnie L. Bassler
- The Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
- Howard Hughes Medical Institute, Chevy Chase, Maryland, United States of America
- * E-mail:
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72
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Differential effects of alkyl gallates on quorum sensing in Pseudomonas aeruginosa. Sci Rep 2019; 9:7741. [PMID: 31123307 PMCID: PMC6533263 DOI: 10.1038/s41598-019-44236-w] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 05/13/2019] [Indexed: 02/07/2023] Open
Abstract
Virulence factors and biofilms constitute attractive targets for the prevention of infections caused by multidrug-resistant bacteria. Among alkyl gallates, propyl gallate (PG) and octyl gallate (OG) are used as food preservatives. Here we found that alkyl gallates differentially affect virulence, biofilm formation, and quorum sensing (QS) in Pseudomonas aeruginosa. Ethyl gallate (EG), PG, and butyl gallate (BG) inhibited biofilm formation and virulence factors including elastase, pyocyanin, and rhamnolipid, in P. aeruginosa without affecting cell viability by antagonizing the QS receptors LasR and RhlR. PG exhibited the most potent activity. Interestingly, hexyl gallate (HG) inhibited the production of rhamnolipid and pyocyanin but did not affect elastase production or biofilm formation. Notably, OG inhibited the production of rhamnolipid and pyocyanin but stimulated elastase production and biofilm formation. Analysis of QS signaling molecule production and QS gene expression suggested that HG inhibited RhlR, while OG activated LasR but inhibited PqsR. This mechanism was confirmed using QS mutants. Additionally, PG prevented the virulence of P. aeruginosa in Caenorhabditis elegans and a mouse model. This is the first report of the differential effects of alkyl gallates on QS systems and PG has great potential as an inhibitor of the virulence and biofilm formation of P. aeruginosa.
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73
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Zhao K, Ma J, Wang X, Guo Y, Yue B, Chu Y. Population divergence of Pseudomonas aeruginosa can lead to the coexistence with Escherichia coli in animal suppurative lesions. Vet Microbiol 2019; 231:169-176. [PMID: 30955805 DOI: 10.1016/j.vetmic.2019.03.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Revised: 02/19/2019] [Accepted: 03/11/2019] [Indexed: 01/09/2023]
Abstract
Purulent disease is the main factor that prevents the population increase of forest musk deer in artificial breeding, and especially the intracorporal suppurative lesions in late-stage with complex bacterial communities normally bring more difficulties for veterinary treatment. Although it is well-recognized that Pseudomonas aeruginosa and Escherichia coli are the two main bacterial pathogens which can be frequently co-isolated from the lung pus of forest musk deer, few studies have explored the interspecific relationship and coexistent mechanism of the two species. In this study, we identified a P. aeruginosa strain MYL-2, which harbored a loss-of-function mutation in the central regulator (LasR) of quorum-sensing (QS) system, from the lung pus of a dying forest musk deer with co-infecting E. coli strain MYL-58. Interestingly, P. aeruginosa MYL-2 could coexist with E. coli MYL-58 compared to the dominant role of lasR-intact P. aeruginosa strain MYL-1 in the competitive experiments. The results of in vitro coevolution assay further revealed that the QS-mediated competitive advantage of P. aeruginosa MYL-1 would be decreased along with the enrichment of lasR mutants in the communities, and P. aeruginosa could finally coexist with E. coli by forming a relatively stable equilibrium. Therefore, these findings provide an evolutionary explanation for the coexistence of P. aeruginosa and E. coli in the suppurative lesions of forest musk deer, and may also contribute to further understanding the pathology of animal purulent disease and the development of novel veterinary therapy.
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Affiliation(s)
- Kelei Zhao
- Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Sichuan Industrial Institute of Antibiotics, Chengdu University, Chengdu 610052, China.
| | - Jinnan Ma
- Key Laboratory of Bio-resources and Eco-environment, Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, 610064, China
| | - Xinrong Wang
- Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Sichuan Industrial Institute of Antibiotics, Chengdu University, Chengdu 610052, China
| | - Yidong Guo
- Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Sichuan Industrial Institute of Antibiotics, Chengdu University, Chengdu 610052, China
| | - Bisong Yue
- Key Laboratory of Bio-resources and Eco-environment, Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, 610064, China
| | - Yiwen Chu
- Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Sichuan Industrial Institute of Antibiotics, Chengdu University, Chengdu 610052, China.
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Turkina MV, Vikström E. Bacteria-Host Crosstalk: Sensing of the Quorum in the Context of Pseudomonas aeruginosa Infections. J Innate Immun 2018; 11:263-279. [PMID: 30428481 DOI: 10.1159/000494069] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 09/24/2018] [Indexed: 12/11/2022] Open
Abstract
Cell-to-cell signaling via small molecules is an essential process to coordinate behavior in single species within a community, and also across kingdoms. In this review, we discuss the quorum sensing (QS) systems used by the opportunistic pathogen Pseudomonas aeruginosa to sense bacterial population density and fitness, and regulate virulence, biofilm development, metabolite acquisition, and mammalian host defense. We also focus on the role of N-acylhomoserine lactone-dependent QS signaling in the modulation of innate immune responses connected together via calcium signaling, homeostasis, mitochondrial and cytoskeletal dynamics, and governing transcriptional and proteomic responses of host cells. A future perspective emphasizes the need for multidisciplinary efforts to bring current knowledge of QS into a more detailed understanding of the communication between bacteria and host, as well as into strategies to prevent and treat P. aeruginosa infections and reduce the rate of antibiotic resistance.
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Affiliation(s)
- Maria V Turkina
- Department of Clinical and Experimental Medicine, Faculty of Medicine and Health Sciences, Linköping University, Linköping, Sweden
| | - Elena Vikström
- Department of Clinical and Experimental Medicine, Faculty of Medicine and Health Sciences, Linköping University, Linköping, Sweden,
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