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Romero-González LE, Montelongo-Martínez LF, González-Valdez A, Quiroz-Morales SE, Cocotl-Yañez M, Franco-Cendejas R, Soberón-Chávez G, Pardo-López L, Bustamante VH. Pseudomonas aeruginosa Isolates from Water Samples of the Gulf of Mexico Show Similar Virulence Properties but Different Antibiotic Susceptibility Profiles than Clinical Isolates. Int J Microbiol 2024; 2024:6959403. [PMID: 38784405 PMCID: PMC11115996 DOI: 10.1155/2024/6959403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Revised: 03/14/2024] [Accepted: 04/27/2024] [Indexed: 05/25/2024] Open
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen found in a wide variety of environments, including soil, water, and habitats associated with animals, humans, and plants. From a One Health perspective, which recognizes the interconnectedness of human, animal, and environmental health, it is important to study the virulence characteristics and antibiotic susceptibility of environmental bacteria. In this study, we compared the virulence properties and the antibiotic resistance profiles of seven isolates collected from the Gulf of Mexico with those of seven clinical strains of P. aeruginosa. Our results indicate that the marine and clinical isolates tested exhibit similar virulence properties; they expressed different virulence factors and were able to kill Galleria mellonella larvae, an animal model commonly used to analyze the pathogenicity of many bacteria, including P. aeruginosa. In contrast, the clinical strains showed higher antibiotic resistance than the marine isolates. Consistently, the clinical strains exhibited a higher prevalence of class 1 integron, an indicator of anthropogenic impact, compared with the marine isolates. Thus, our results indicate that the P. aeruginosa marine strains analyzed in this study, isolated from the Gulf of Mexico, have similar virulence properties, but lower antibiotic resistance, than those from hospitals.
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Affiliation(s)
- Luis E. Romero-González
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, Mexico
| | - Luis F. Montelongo-Martínez
- Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad Universitaria, Ciudad de México, Coyoacán, Mexico
| | - Abigail González-Valdez
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, Ciudad de México, Coyoacán, Mexico
| | - Sara E. Quiroz-Morales
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, Ciudad de México, Coyoacán, Mexico
| | - Miguel Cocotl-Yañez
- Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad Universitaria, Ciudad de México, Coyoacán, Mexico
| | - Rafael Franco-Cendejas
- Instituto Nacional de Rehabilitación “Luis Guillermo Ibarra Ibarra,” Ciudad de México, Mexico
| | - Gloria Soberón-Chávez
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, Ciudad de México, Coyoacán, Mexico
| | - Liliana Pardo-López
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, Mexico
| | - Víctor H. Bustamante
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, Mexico
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Koh CMM, Ping LSY, Xuan CHH, Theng LB, San HS, Palombo EA, Wezen XC. A data-driven machine learning approach for discovering potent LasR inhibitors. Bioengineered 2023; 14:2243416. [PMID: 37552115 PMCID: PMC10411317 DOI: 10.1080/21655979.2023.2243416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Revised: 07/26/2023] [Accepted: 07/28/2023] [Indexed: 08/09/2023] Open
Abstract
The rampant spread of multidrug-resistant Pseudomonas aeruginosa strains severely threatens global health. This severity is compounded against the backdrop of a stagnating antibiotics development pipeline. Moreover, with many promising therapeutics falling short of expectations in clinical trials, targeting the las quorum sensing (QS) system remains an attractive therapeutic strategy to combat P. aeruginosa infection. Thus, our primary goal was to develop a drug prediction algorithm using machine learning to identify potent LasR inhibitors. In this work, we demonstrated using a Multilayer Perceptron (MLP) algorithm boosted with AdaBoostM1 to discriminate between active and inactive LasR inhibitors. The optimal model performance was evaluated using 5-fold cross-validation and test sets. Our best model achieved a 90.7% accuracy in distinguishing active from inactive LasR inhibitors, an area under the Receiver Operating Characteristic Curve value of 0.95, and a Matthews correlation coefficient value of 0.81 when evaluated using test sets. Subsequently, we deployed the model against the Enamine database. The top-ranked compounds were further evaluated for their target engagement activity using molecular docking studies, Molecular Dynamics simulations, MM-GBSA analysis, and Free Energy Landscape analysis. Our data indicate that several of our chosen top hits showed better ligand-binding affinities than naringenin, a competitive LasR inhibitor. Among the six top hits, five of these compounds were predicted to be LasR inhibitors that could be used to treat P. aeruginosa-associated infections. To our knowledge, this study provides the first assessment of using an MLP-based QSAR model for discovering potent LasR inhibitors to attenuate P. aeruginosa infections.
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Affiliation(s)
- Christabel Ming Ming Koh
- Faculty of Engineering, Computing, and Science, Swinburne University of Technology, Sarawak, Malaysia
| | - Lilian Siaw Yung Ping
- Faculty of Engineering, Computing, and Science, Swinburne University of Technology, Sarawak, Malaysia
| | - Christopher Ha Heng Xuan
- Faculty of Engineering, Computing, and Science, Swinburne University of Technology, Sarawak, Malaysia
| | - Lau Bee Theng
- Faculty of Engineering, Computing, and Science, Swinburne University of Technology, Sarawak, Malaysia
| | - Hwang Siaw San
- Faculty of Engineering, Computing, and Science, Swinburne University of Technology, Sarawak, Malaysia
| | - Enzo A. Palombo
- Department of Chemistry and Biotechnology, Swinburne University of Technology, Hawthorn, Victoria, Australia
| | - Xavier Chee Wezen
- Faculty of Engineering, Computing, and Science, Swinburne University of Technology, Sarawak, Malaysia
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Ruhal R, Ghosh M, Kumar V, Jain D. Mutation of putative glycosyl transferases PslC and PslI confers susceptibility to antibiotics and leads to drastic reduction in biofilm formation in Pseudomonas aeruginosa. MICROBIOLOGY (READING, ENGLAND) 2023; 169:001392. [PMID: 37702709 PMCID: PMC10569066 DOI: 10.1099/mic.0.001392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Accepted: 08/31/2023] [Indexed: 09/14/2023]
Abstract
Pseudomonas aeruginosa is an opportunistic, multidrug-resistant pathogen capable of adapting to numerous environmental conditions and causing fatal infections in immunocompromised patients. The predominant lifestyle of P. aeruginosa is in the form of biofilms, which are structured communities of bacteria encapsulated in a matrix containing exopolysaccharides, extracellular DNA (eDNA) and proteins. The matrix is impervious to antibiotics, rendering the bacteria tolerant to antimicrobials. P. aeruginosa also produces a plethora of virulence factors such as pyocyanin, rhamnolipids and lipopolysaccharides among others. In this study we present the molecular characterization of pslC and pslI genes, of the exopolysaccharide operon, that code for putative glycosyltransferases. PslC is a 303 amino acid containing putative GT2 glycosyltrasferase, whereas PslI is a 367 aa long protein, possibly functioning as a GT4 glycosyltransferase. Mutation in either of these two genes results in a significant reduction in biofilm biomass with concomitant decline in c-di-GMP levels in the bacterial cells. Moreover, mutation in pslC and pslI dramatically increased susceptibility of P. aeruginosa to tobramycin, colistin and ciprofloxacin. Additionally, these mutations also resulted in an increase in rhamnolipids and pyocyanin formation. We demonstrate that elevated rhamnolipids promote a swarming phenotype in the mutant strains. Together these results highlight the importance of PslC and PslI in the biogenesis of biofilms and their potential as targets for increased antibiotic susceptibility and biofilm inhibition.
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Affiliation(s)
- Rohit Ruhal
- Transcription Regulation Lab, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone, Faridabad-Gurgaon Expressway, Faridabad, 121001, India
| | - Moumita Ghosh
- Transcription Regulation Lab, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone, Faridabad-Gurgaon Expressway, Faridabad, 121001, India
| | - Vineet Kumar
- Transcription Regulation Lab, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone, Faridabad-Gurgaon Expressway, Faridabad, 121001, India
| | - Deepti Jain
- Transcription Regulation Lab, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone, Faridabad-Gurgaon Expressway, Faridabad, 121001, India
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4
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Montelongo-Martínez LF, Hernández-Méndez C, Muriel-Millan LF, Hernández-Estrada R, Fabian-Del Olmo MJ, González-Valdez A, Soberón-Chávez G, Cocotl-Yañez M. Unraveling the regulation of pyocyanin synthesis by RsmA through MvaU and RpoS in Pseudomonas aeruginosa ID4365. J Basic Microbiol 2023; 63:51-63. [PMID: 36207285 DOI: 10.1002/jobm.202200432] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 09/05/2022] [Accepted: 09/18/2022] [Indexed: 01/04/2023]
Abstract
Pyocyanin is a phenazine with redox activity produced by Pseudomonas aeruginosa that is harmful to other bacteria and eukaryotic organisms by generating reactive oxygen species. Gene regulation of pyocyanin synthesis has been addressed in the PAO1 and PA14 strains and involves the three-quorum sensing systems Las, Rhl, and Pqs; the regulators RsaL, MvaU, and RpoS, and the posttranscriptional Rsm system, among others. Here, we determined how RsmA regulates pyocyanin synthesis in P. aeruginosa ID4365, an overproducer strain. We found that, in the protease peptone glucose ammonium salts medium, rsmA inactivation increases pyocyanin production compared with the wild-type strains ID4365, PAO, and PA14. We showed that RsmA regulates inversely the expression of both phz operons involved in pyocyanin synthesis; particularly the phz2 operon is positively regulated at the transcriptional level indirectly through MvaU. In addition, we found that the phz1 operon contributes mainly to pyocyanin synthesis and that RsmA negatively regulates phzM and phzS expression. Finally, we showed that translation of the sigma factor RpoS is positively regulated by RsmA, and the expression of rpoS under an independent promoter decreases pyocyanin production in the IDrsmA strain. These results indicate that RsmA regulates not only the genes for pyocyanin production but also their regulators.
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Affiliation(s)
- Luis F Montelongo-Martínez
- Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, México City, México
| | - Cristina Hernández-Méndez
- Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, México City, México
| | - Luis F Muriel-Millan
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México City, México
| | - René Hernández-Estrada
- Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, México City, México
| | - Misael J Fabian-Del Olmo
- Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, México City, México
| | - Abigail González-Valdez
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México City, México
| | - Gloria Soberón-Chávez
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México City, México
| | - Miguel Cocotl-Yañez
- Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, México City, México
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Molecular Mechanisms and Applications of N-Acyl Homoserine Lactone-Mediated Quorum Sensing in Bacteria. Molecules 2022; 27:molecules27217584. [PMID: 36364411 PMCID: PMC9654057 DOI: 10.3390/molecules27217584] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2022] [Revised: 11/02/2022] [Accepted: 11/02/2022] [Indexed: 11/09/2022] Open
Abstract
Microbial biodiversity includes biotic and abiotic components that support all life forms by adapting to environmental conditions. Climate change, pollution, human activity, and natural calamities affect microbial biodiversity. Microbes have diverse growth conditions, physiology, and metabolism. Bacteria use signaling systems such as quorum sensing (QS) to regulate cellular interactions via small chemical signaling molecules which also help with adaptation under undesirable survival conditions. Proteobacteria use acyl-homoserine lactone (AHL) molecules as autoinducers to sense population density and modulate gene expression. The LuxI-type enzymes synthesize AHL molecules, while the LuxR-type proteins (AHL transcriptional regulators) bind to AHLs to regulate QS-dependent gene expression. Diverse AHLs have been identified, and the diversity extends to AHL synthases and AHL receptors. This review comprehensively explains the molecular diversity of AHL signaling components of Pseudomonas aeruginosa, Chromobacterium violaceum, Agrobacterium tumefaciens, and Escherichia coli. The regulatory mechanism of AHL signaling is also highlighted in this review, which adds to the current understanding of AHL signaling in Gram-negative bacteria. We summarize molecular diversity among well-studied QS systems and recent advances in the role of QS proteins in bacterial cellular signaling pathways. This review describes AHL-dependent QS details in bacteria that can be employed to understand their features, improve environmental adaptation, and develop broad biomolecule-based biotechnological applications.
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Soto-Aceves MP, González-Valdez A, Cocotl-Yañez M, Soberón-Chávez G. Pseudomonas aeruginosa LasR overexpression leads to a RsaL-independent pyocyanin production inhibition in a low phosphate condition. MICROBIOLOGY (READING, ENGLAND) 2022; 168. [PMID: 36301076 DOI: 10.1099/mic.0.001262] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Several Pseudomonas aeruginosa virulence-related traits like pyocyanin are regulated by an intricate regulatory network called quorum sensing (QS) that relies on transcriptional regulators that are activated through binding to a self-produced molecule called an autoinducer (AI). QS is composed of three systems, Las, Rhl and Pqs. In the Las system, the regulatory protein LasR interacts with its AI to activate the other two QS systems. In turn, the Rhl and Pqs systems regulate the expression of multiple virulence-related genes, such as the genes of the reiterated operons phzA1B1C1D1E1F1G1 and phzA2B2C2D2E2F2G2 involved in pyocyanin production. The Las system also regulates the negative regulator RsaL, which provides negative feedback to the QS-response, including repression of pyocyanin synthesis genes. In this work, we describe that LasR can act as a negative regulator of phzA1 transcription and hence of pyocyanin production and that this regulation is independent of RsaL activity. This work contributes to the understanding of QS-dependent pyocyanin production and demonstrates a previously uncharacterized role of LasR as a repressor.
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Affiliation(s)
- Martín Paolo Soto-Aceves
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico.,Present address: Department of Microbiology, University of Washington, Seattle, Washington, USA
| | - Abigail González-Valdez
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Miguel Cocotl-Yañez
- Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Gloria Soberón-Chávez
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
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Wang Y, Pan L, Li L, Cao R, Zheng Q, Xu Z, Wu CJ, Zhu H. Glycosylation increases the anti-QS as well as anti-biofilm and anti-adhesion ability of the cyclo (L-Trp-L-Ser) against Pseudomonas aeruginosa. Eur J Med Chem 2022; 238:114457. [DOI: 10.1016/j.ejmech.2022.114457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2022] [Revised: 04/29/2022] [Accepted: 05/09/2022] [Indexed: 11/03/2022]
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Resistance Is Not Futile: The Role of Quorum Sensing Plasticity in Pseudomonas aeruginosa Infections and Its Link to Intrinsic Mechanisms of Antibiotic Resistance. Microorganisms 2022; 10:microorganisms10061247. [PMID: 35744765 PMCID: PMC9228389 DOI: 10.3390/microorganisms10061247] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 06/06/2022] [Accepted: 06/09/2022] [Indexed: 01/01/2023] Open
Abstract
Bacteria use a cell-cell communication process called quorum sensing (QS) to orchestrate collective behaviors. QS relies on the group-wide detection of extracellular signal molecules called autoinducers (AI). Quorum sensing is required for virulence and biofilm formation in the human pathogen Pseudomonas aeruginosa. In P. aeruginosa, LasR and RhlR are homologous LuxR-type soluble transcription factor receptors that bind their cognate AIs and activate the expression of genes encoding functions required for virulence and biofilm formation. While some bacterial signal transduction pathways follow a linear circuit, as phosphoryl groups are passed from one carrier protein to another ultimately resulting in up- or down-regulation of target genes, the QS system in P. aeruginosa is a dense network of receptors and regulators with interconnecting regulatory systems and outputs. Once activated, it is not understood how LasR and RhlR establish their signaling hierarchy, nor is it clear how these pathway connections are regulated, resulting in chronic infection. Here, we reviewed the mechanisms of QS progression as it relates to bacterial pathogenesis and antimicrobial resistance and tolerance.
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Sultan M, Arya R, Kim KK. Roles of Two-Component Systems in Pseudomonas aeruginosa Virulence. Int J Mol Sci 2021; 22:12152. [PMID: 34830033 PMCID: PMC8623646 DOI: 10.3390/ijms222212152] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 11/01/2021] [Accepted: 11/02/2021] [Indexed: 12/28/2022] Open
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen that synthesizes and secretes a wide range of virulence factors. P. aeruginosa poses a potential threat to human health worldwide due to its omnipresent nature, robust host accumulation, high virulence, and significant resistance to multiple antibiotics. The pathogenicity of P. aeruginosa, which is associated with acute and chronic infections, is linked with multiple virulence factors and associated secretion systems, such as the ability to form and utilize a biofilm, pili, flagella, alginate, pyocyanin, proteases, and toxins. Two-component systems (TCSs) of P. aeruginosa perform an essential role in controlling virulence factors in response to internal and external stimuli. Therefore, understanding the mechanism of TCSs to perceive and respond to signals from the environment and control the production of virulence factors during infection is essential to understanding the diseases caused by P. aeruginosa infection and further develop new antibiotics to treat this pathogen. This review discusses the important virulence factors of P. aeruginosa and the understanding of their regulation through TCSs by focusing on biofilm, motility, pyocyanin, and cytotoxins.
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Affiliation(s)
| | - Rekha Arya
- Department of Precision Medicine, Graduate School of Basic Medical Science (GSBMS), Institute for Antimicrobial Resistance Research and Therapeutics, Sungkyunkwan University School of Medicine, Suwon 16419, Korea;
| | - Kyeong Kyu Kim
- Department of Precision Medicine, Graduate School of Basic Medical Science (GSBMS), Institute for Antimicrobial Resistance Research and Therapeutics, Sungkyunkwan University School of Medicine, Suwon 16419, Korea;
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Laborda P, Sanz-García F, Hernando-Amado S, Martínez JL. Pseudomonas aeruginosa: an antibiotic resilient pathogen with environmental origin. Curr Opin Microbiol 2021; 64:125-132. [PMID: 34710741 DOI: 10.1016/j.mib.2021.09.010] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 08/31/2021] [Accepted: 09/23/2021] [Indexed: 12/24/2022]
Abstract
Pseudomonas aeruginosa, a bacterium characterized for its low antibiotics' susceptibility, is one of the most relevant opportunistic pathogens, causing infections at hospitals and in cystic fibrosis patients. Besides its relevance for human health, P. aeruginosa colonizes environmental ecosystems; therefore the elements driving its infectivity and antibiotic resistance must be analyzed from a One-Health perspective. Although some epidemic clones have been described, there are not specific lineages linked to infections, suggesting that P. aeruginosa virulence and antibiotic resistance determinants evolved in nature to play functions other than infecting the human host and avoiding antimicrobial treatment. Herein, we review current information on the population structure of P. aeruginosa and on the functional role that its resistance and virulence determinants have in non-clinical ecosystems.
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Affiliation(s)
- Pablo Laborda
- Centro Nacional de Biotecnología, CSIC, 28049, Madrid, Spain
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García-Reyes S, Cocotl-Yañez M, Soto-Aceves MP, González-Valdez A, Servín-González L, Soberón-Chávez G. PqsR-independent quorum-sensing response of Pseudomonas aeruginosa ATCC 9027 outlier-strain reveals new insights on the PqsE effect on RhlR activity. Mol Microbiol 2021; 116:1113-1123. [PMID: 34418194 DOI: 10.1111/mmi.14797] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 08/16/2021] [Accepted: 08/17/2021] [Indexed: 11/28/2022]
Abstract
Pseudomonas aeruginosa is a ubiquitous environmental bacterium and an opportunistic pathogen that represents an important health hazard. The quorum-sensing response regulates the expression of several virulence factors and involves three regulons: Las, Rhl, and Pqs. The P. aeruginosa ATCC 9027 strain, which belongs to the genetically diverse PA7 clade, contains a frame-shift mutation in the pqsR gene that encodes a transcriptional activator necessary for pyocyanin (PYO) synthesis in type strains PAO1 and PA14. Here we characterize the PqsE-dependent production of PYO in strain ATCC 9027. We show that this strain expresses pqsE independently of PqsR and in the absence of quinolone production, and that PqsE promotes the RhlR-dependent production of PYO, yet this production is not strictly dependent on PqsE. In addition, we show that in both strains ATCC 9027 and PAO1, PqsE overexpression causes an increased concentration of RhlR and enhances PYO production but does not affect rhamnolipids (RL) production in the same way. These results suggest that PqsE interaction with RhlR preferentially modifies its ability to activate transcription of genes involved in PYO production and provide new evidence about PqsE-dependent RhlR activation, highlighting the variability of the QS response among different P. aeruginosa clades and strains. HIGHLIGHTS: Pseudomonas aeruginosa ATCC 9027 is able to produce pyocyanin in phosphate limiting conditions, even in the absence of a functional PqsR. This strain does not produce alkyl quinolones like PQS and HHQ, but expresses pqsE. Synthesis of pyocyanin by ATCC 9027 is only partially dependent on pqsE. The overexpression of pqsE in the ATCC 9027 and PAO1 strains causes pyocyanin overproduction. The overexpression of pqsE in these strains causes an increased RhlR concentration without affecting rhlR transcription or translation. Rhamnolipids production is not affected to the same extent as pyocyanin by overexpression of pqsE in these strains.
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Affiliation(s)
- Selene García-Reyes
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, Ciudad de Mexico, Mexico
| | - Miguel Cocotl-Yañez
- Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad Universitaria, Ciudad de Mexico, Mexico
| | - Martín Paolo Soto-Aceves
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, Ciudad de Mexico, Mexico
| | - Abigail González-Valdez
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, Ciudad de Mexico, Mexico
| | - Luis Servín-González
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, Ciudad de Mexico, Mexico
| | - Gloria Soberón-Chávez
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, Ciudad de Mexico, Mexico
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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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Soberón‐Chávez G, González‐Valdez A, Soto‐Aceves MP, Cocotl‐Yañez M. Rhamnolipids produced by Pseudomonas: from molecular genetics to the market. Microb Biotechnol 2021; 14:136-146. [PMID: 33151628 PMCID: PMC7888470 DOI: 10.1111/1751-7915.13700] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 10/18/2020] [Accepted: 10/20/2020] [Indexed: 12/31/2022] Open
Abstract
Rhamnolipids are biosurfactants with a wide range of industrial applications that entered into the market a decade ago. They are naturally produced by Pseudomonas aeruginosa and some Burkholderia species. Occasionally, some strains of different bacterial species, like Pseudomonas chlororaphis NRRL B-30761, which have acquired RL-producing ability by horizontal gene transfer, have been described. P. aeruginosa, the ubiquitous opportunistic pathogenic bacterium, is the best rhamnolipids producer, but Pseudomonas putida has been used as heterologous host for the production of this biosurfactant with relatively good yields. The molecular genetics of rhamnolipids production by P. aeruginosa has been widely studied not only due to the interest in developing overproducing strains, but because it is coordinately regulated with the expression of different virulence-related traits by the quorum-sensing response. Here, we highlight how the research of the molecular mechanisms involved in rhamnolipid production have impacted the development of strains that are suitable for industrial production of this biosurfactant, as well as some perspectives to improve these industrial useful strains.
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Affiliation(s)
- Gloria Soberón‐Chávez
- Departamento de Biología Molecular y BiotecnologíaInstituto de Investigaciones BiomédicasUniversidad Nacional Autónoma de MéxicoCiudad Universitaria, CDMXCoyoacanMéxico
| | - Abigail González‐Valdez
- Departamento de Biología Molecular y BiotecnologíaInstituto de Investigaciones BiomédicasUniversidad Nacional Autónoma de MéxicoCiudad Universitaria, CDMXCoyoacanMéxico
| | - Martín P. Soto‐Aceves
- Departamento de Biología Molecular y BiotecnologíaInstituto de Investigaciones BiomédicasUniversidad Nacional Autónoma de MéxicoCiudad Universitaria, CDMXCoyoacanMéxico
| | - Miguel Cocotl‐Yañez
- Departamento de Microbiología y ParasitologíaFacultad de MedicinaUniversidad Nacional Autónoma de MéxicoCiudad Universitaria, CDMXCoyoacanMéxico
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