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Manisha Y, Srinivasan M, Jobichen C, Rosenshine I, Sivaraman J. Sensing for survival: specialised regulatory mechanisms of Type III secretion systems in Gram-negative pathogens. Biol Rev Camb Philos Soc 2024; 99:837-863. [PMID: 38217090 DOI: 10.1111/brv.13047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 12/14/2023] [Accepted: 12/19/2023] [Indexed: 01/15/2024]
Abstract
For centuries, Gram-negative pathogens have infected the human population and been responsible for numerous diseases in animals and plants. Despite advancements in therapeutics, Gram-negative pathogens continue to evolve, with some having developed multi-drug resistant phenotypes. For the successful control of infections caused by these bacteria, we need to widen our understanding of the mechanisms of host-pathogen interactions. Gram-negative pathogens utilise an array of effector proteins to hijack the host system to survive within the host environment. These proteins are secreted into the host system via various secretion systems, including the integral Type III secretion system (T3SS). The T3SS spans two bacterial membranes and one host membrane to deliver effector proteins (virulence factors) into the host cell. This multifaceted process has multiple layers of regulation and various checkpoints. In this review, we highlight the multiple strategies adopted by these pathogens to regulate or maintain virulence via the T3SS, encompassing the regulation of small molecules to sense and communicate with the host system, as well as master regulators, gatekeepers, chaperones, and other effectors that recognise successful host contact. Further, we discuss the regulatory links between the T3SS and other systems, like flagella and metabolic pathways including the tricarboxylic acid (TCA) cycle, anaerobic metabolism, and stringent cell response.
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Affiliation(s)
- Yadav Manisha
- Department of Biological Sciences, National University of Singapore, Singapore, 117543, Singapore
| | - Mahalashmi Srinivasan
- Department of Biological Sciences, National University of Singapore, Singapore, 117543, Singapore
| | - Chacko Jobichen
- Department of Biological Sciences, National University of Singapore, Singapore, 117543, Singapore
| | - Ilan Rosenshine
- Department of Microbiology and Molecular Genetics, The Hebrew University of Jerusalem, Ein Kerem, Jerusalem, 91120, Israel
| | - J Sivaraman
- Department of Biological Sciences, National University of Singapore, Singapore, 117543, Singapore
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Batista BB, de Lima VM, Picinato BA, Koide T, da Silva Neto JF. A quorum-sensing regulatory cascade for siderophore-mediated iron homeostasis in Chromobacterium violaceum. mSystems 2024; 9:e0139723. [PMID: 38501880 PMCID: PMC11019928 DOI: 10.1128/msystems.01397-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Accepted: 02/24/2024] [Indexed: 03/20/2024] Open
Abstract
Iron is a transition metal used as a cofactor in many biochemical reactions. In bacteria, iron homeostasis involves Fur-mediated de-repression of iron uptake systems, such as the iron-chelating compounds siderophores. In this work, we identified and characterized novel regulatory systems that control siderophores in the environmental opportunistic pathogen Chromobacterium violaceum. Screening of a 10,000-transposon mutant library for siderophore halos identified seven possible regulatory systems involved in siderophore-mediated iron homeostasis in C. violaceum. Further characterization revealed a regulatory cascade that controls siderophores involving the transcription factor VitR acting upstream of the quorum-sensing (QS) system CviIR. Mutation of the regulator VitR led to an increase in siderophore halos, and a decrease in biofilm, violacein, and protease production. We determined that these effects occurred due to VitR-dependent de-repression of vioS. Increased VioS leads to direct inhibition of the CviR regulator by protein-protein interaction. Indeed, insertion mutations in cviR and null mutations of cviI and cviR led to an increase of siderophore halos. RNA-seq of the cviI and cviR mutants revealed that CviR regulates CviI-dependent and CviI-independent regulons. Classical QS-dependent processes (violacein, proteases, and antibiotics) were activated at high cell density by both CviI and CviR. However, genes related to iron homeostasis and many other processes were regulated by CviR but not CviI, suggesting that CviR acts without its canonical CviI autoinducer. Our data revealed a complex regulatory cascade involving QS that controls siderophore-mediated iron homeostasis in C. violaceum.IMPORTANCEThe iron-chelating compounds siderophores play a major role in bacterial iron acquisition. Here, we employed a genetic screen to identify novel siderophore regulatory systems in Chromobacterium violaceum, an opportunistic human pathogen. Many mutants with increased siderophore halos had transposon insertions in genes encoding transcription factors, including a novel regulator called VitR, and CviR, the regulator of the quorum-sensing (QS) system CviIR. We found that VitR is upstream in the pathway and acts as a dedicated repressor of vioS, which encodes a direct CviR-inhibitory protein. Indeed, all QS-related phenotypes of a vitR mutant were rescued in a vitRvioS mutant. At high cell density, CviIR activated classical QS-dependent processes (violacein, proteases, and antibiotics production). However, genes related to iron homeostasis and type-III and type-VI secretion systems were regulated by CviR in a CviI- or cell density-independent manner. Our data unveil a complex regulatory cascade integrating QS and siderophores in C. violaceum.
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Affiliation(s)
- Bianca B. Batista
- Departamento de Biologia Celular e Molecular e Bioagentes Patogênicos, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Vinicius M. de Lima
- Departamento de Biologia Celular e Molecular e Bioagentes Patogênicos, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Beatriz A. Picinato
- Departamento de Bioquímica e Imunologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Tie Koide
- Departamento de Bioquímica e Imunologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - José F. da Silva Neto
- Departamento de Biologia Celular e Molecular e Bioagentes Patogênicos, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, São Paulo, Brazil
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Tan X, Hu M, Cheng X, Xiao J, Zhou J, Zhu G. Effects of elevated levels of intracellular nitric oxide on Pseudomonas aeruginosa biofilm in chronic skin wound and slow-killing infection models. Int Microbiol 2024; 27:349-359. [PMID: 37410300 DOI: 10.1007/s10123-023-00395-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 06/19/2023] [Accepted: 06/29/2023] [Indexed: 07/07/2023]
Abstract
Nitric oxide (NO), produced through the denitrification pathway, regulates biofilm dynamics through the quorum sensing system in Pseudomonas aeruginosa. NO stimulates P. aeruginosa biofilm dispersal by enhancing phosphodiesterase activity to decrease cyclic di-GMP levels. In a chronic skin wound model containing a mature biofilm, the gene expression of nirS, encoding nitrite reductase to produce NO, was low, leading to reduced intracellular NO levels. Although low-dose NO induces biofilm dispersion, it is unknown whether it influences the formation of P. aeruginosa biofilms in chronic skin wounds. In this study, a P. aeruginosa PAO1 strain with overexpressed nirS was established to investigate NO effects on P. aeruginosa biofilm formation in an ex vivo chronic skin wound model and unravel the underlying molecular mechanisms. Elevated intracellular NO levels altered the biofilm structure in the wound model by inhibiting the expression of quorum sensing-related genes, which was different from an in vitro model. In Caenorhabditis elegans as a slow-killing infection model, elevated intracellular NO levels increased worms' lifespan by 18%. Worms that fed on the nirS-overexpressed PAO1 strain for 4 h had complete tissue, whereas worms that fed on empty plasmid-containing PAO1 had biofilms on their body, causing severe damage to the head and tail. Thus, elevated intracellular NO levels can inhibit P. aeruginosa biofilm growth in chronic skin wounds and reduce pathogenicity to the host. Targeting NO is a potential approach to control biofilm growth in chronic skin wounds wherein P. aeruginosa biofilms are a persistent problem.
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Affiliation(s)
- Xiaojuan Tan
- Anhui Provincial Key Laboratory of Molecular Enzymology and Mechanism of Major Diseases, College of Life Sciences, Anhui Normal University, Wuhu, 241000, Anhui, China.
| | - Mei Hu
- Anhui Provincial Key Laboratory of Molecular Enzymology and Mechanism of Major Diseases, College of Life Sciences, Anhui Normal University, Wuhu, 241000, Anhui, China
| | - Xi Cheng
- Anhui Provincial Key Laboratory of Molecular Enzymology and Mechanism of Major Diseases, College of Life Sciences, Anhui Normal University, Wuhu, 241000, Anhui, China
| | - Jingjing Xiao
- Anhui Provincial Key Laboratory of Molecular Enzymology and Mechanism of Major Diseases, College of Life Sciences, Anhui Normal University, Wuhu, 241000, Anhui, China
| | - Jinwei Zhou
- School of Food and Biology Engineering, Xuzhou University of Technology, Xuzhou, 221018, Jiangsu, China.
| | - Guoping Zhu
- Anhui Provincial Key Laboratory of Molecular Enzymology and Mechanism of Major Diseases, College of Life Sciences, Anhui Normal University, Wuhu, 241000, Anhui, China.
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Tse-Kang S, Wani KA, Peterson ND, Page A, Pukkila-Worley R. Activation of intestinal immunity by pathogen effector-triggered aggregation of lysosomal TIR-1/SARM1. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.12.04.569946. [PMID: 38106043 PMCID: PMC10723332 DOI: 10.1101/2023.12.04.569946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
TIR-domain proteins with enzymatic activity are essential for immunity in plants, animals, and bacteria. However, it is not known how these proteins function in pathogen sensing in animals. We discovered that a TIR-domain protein (TIR-1/SARM1) is strategically expressed on the membranes of a lysosomal sub-compartment, which enables intestinal epithelial cells in the nematode C. elegans to survey for pathogen effector-triggered host damage. We showed that a redox active virulence effector secreted by the bacterial pathogen Pseudomonas aeruginosa alkalinized and condensed a specific subset of lysosomes by inducing intracellular oxidative stress. Concentration of TIR-1/SARM1 on the surface of these organelles triggered its multimerization, which engages its intrinsic NADase activity, to activate the p38 innate immune pathway and protect the host against microbial intoxication. Thus, lysosomal TIR-1/SARM1 is a sensor for oxidative stress induced by pathogenic bacteria to activate metazoan intestinal immunity.
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Rahman MM, Islam MR, Talukder MEK, Atif MF, Alam R, Uddin AFMS, Anis-Ul-Haque KM, Islam MS, Uddn MJ, Akhter S. Unveiling therapeutic efficacy of extract and multi-targeting phytocompounds from Christella dentata (Forssk.) Brownsey & Jermy against multidrug-resistant Pseudomonas aeruginosa. RSC Adv 2024; 14:6096-6111. [PMID: 38370460 PMCID: PMC10871032 DOI: 10.1039/d3ra08367e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Accepted: 01/09/2024] [Indexed: 02/20/2024] Open
Abstract
Christella dentata (Forssk.) Brownsey & Jermy has been commonly used in traditional medicinal practices but its effects on multi-drug-resistant (MDR) bacteria have remained unexplored. We aimed to assess the in vitro antibacterial potential of the ethanol extract of Christella dentata (EECD) against MDR Pseudomonas aeruginosa and to identify potential multi-targeting antibacterial phytocompounds through computer-aided drug design focusing on the LasR and LpxC proteins. PPS, FT-IR and GC-MS were used for profiling of the phytocompounds in EECD. The antimicrobial activity of EECD was assessed using in vitro agar well diffusion, disc diffusion, MIC and MBC. Computer-aided drug design was used to identify multi-targeting leads from GC-MS-annotated phytocompounds. EECD exhibited dose-dependent antibacterial activity and revealed the presence of 51 phytocompounds in GC-MS analysis. Among these, three phytocompounds; (2E,4E)-N-isobutylhexadeca-2,4-dienamide (CID 6442402), bicyclo[4.3.0]nonane, 2,2,6,7-tetramethyl-7-hydroxy- (CID 536446) and 1,4-diethylbenzene (CID 7734) were identified as promising antibacterial phytocompounds as they strongly bonded with LasR and LpxC. Of them, CID 536446 and CID 7734 exhibited multiple targeting abilities with LasR and LpxC. On further screening, both CID 536446 and CID 7734 exhibited favorable drug-able, pharmacokinetics and toxicity properties. Finally, molecular dynamics (MD) simulation proved the binding stability of bicyclo[4.3.0]nonane, 2,2,6,7-tetramethyl-7-hydroxy- and 1,4-diethylbenzene to active pockets of LasR and LpxC. The results of this study offer scientific validation for the traditional use of Christella dentata in bacterial infection-related diseases. It also suggests that bicyclo[4.3.0]nonane, 2,2,6,7-tetramethyl-7-hydroxy- and 1,4-diethylbenzene from Christella dentata might be responsible for the antibacterial activity and could act as phytopharmacological leads for the development of LasR and LpxC inhibitors against MDR P. aeruginosa.
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Affiliation(s)
- Md Mashiar Rahman
- Molecular and Cellular Biology Laboratory, Department of Genetic Engineering and Biotechnology, Jashore University of Science and Technology Jashore 7408 Bangladesh
| | - Md Rakibul Islam
- Molecular and Cellular Biology Laboratory, Department of Genetic Engineering and Biotechnology, Jashore University of Science and Technology Jashore 7408 Bangladesh
| | - Md Enamul Kabir Talukder
- Molecular and Cellular Biology Laboratory, Department of Genetic Engineering and Biotechnology, Jashore University of Science and Technology Jashore 7408 Bangladesh
| | - Md Farhan Atif
- Molecular and Cellular Biology Laboratory, Department of Genetic Engineering and Biotechnology, Jashore University of Science and Technology Jashore 7408 Bangladesh
| | - Rahat Alam
- Molecular and Cellular Biology Laboratory, Department of Genetic Engineering and Biotechnology, Jashore University of Science and Technology Jashore 7408 Bangladesh
| | - A F M Shahab Uddin
- Department of Computer Science and Engineering, Jashore University of Science and Technology Jashore 7408 Bangladesh
| | - K M Anis-Ul-Haque
- Department of Chemistry, Jashore University of Science and Technology Jashore 7408 Bangladesh
| | - Md Saidul Islam
- Korea Institute of Radiological & Medical Sciences 75, Nowon-ro, Nowon-gu Seoul South Korea
| | - Mohammad Jashim Uddn
- Department of Pharmacy, Jashore University of Science and Technology Jashore 7408 Bangladesh
| | - Shahina Akhter
- Department of Biochemistry and Biotechnology, University of Science and Technology Chittagong (USTC) Foy's Lake Chittagong 4202 Bangladesh
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Azimzadeh M, Greco G, Farmani A, Pourhajibagher M, Taherkhani A, Alikhani MY, Bahador A. Synergistic effects of nano curcumin mediated photodynamic inactivation and nano-silver@colistin against Pseudomonas aeruginosa biofilms. Photodiagnosis Photodyn Ther 2024; 45:103971. [PMID: 38218569 DOI: 10.1016/j.pdpdt.2024.103971] [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: 11/17/2023] [Revised: 01/10/2024] [Accepted: 01/10/2024] [Indexed: 01/15/2024]
Abstract
BACKGROUND Patients with burn injuries colonized by multidrug-resistant Pseudomonas aeruginosa face increased mortality risk. The efficacy of colistin, a last-resort treatment, is declining as resistance levels rise. P. aeruginosa's robust biofilm exacerbates antibiotic resistance. Photodynamic Inactivation (PDI) shows promise in fighting biofilm. MATERIALS AND METHODS Nano curcumin (nCur) particles were synthesized, and their chemical characteristics were determined using zeta potential (ZP), dynamic light scattering analysis (DLS), energy-dispersive X-ray (EDX) analysis, and fourier transform infrared (FTIR). We conducted an MTT assay to assess the cytotoxicity of nCur-mediated PDI in combination with nanosilver colistin. The fractional biofilm inhibitory concentration (FBIC) of two P. aeruginosa clinical isolates and P. aeruginosa ATCC 27853 during nCur-mediated PDI@AgNPs@CL was determined using a 3-dimensional (3-D) checkerboard assay. To study the effect of nCur-mediated PDI@AgNPs@CL on lasI, lasR, rhlI, rhlR, pelA, and pslA gene expression, Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was conducted at each isolate's FBIC. The impact of treatments was also investigated using scanning electron microscopy (SEM). RESULTS The ZP and mean DLS values of the nCur were 10.3 mV and 402.6 ± 24.6 nm, respectively. The distinct functional groups of nCur corresponded with the peaks of FTIR absorption. Moreover, the EDX analysis showed the ratios of different metals in nCur. Cell viability percentages of nCur-mediated PDI@AgNPs@CL at FBIC concentrations of clinical isolates Nos. 30, 354, and P. aeruginosa ATCC 27853 were 91.36 %, 83.20 %, and 92.48 %, respectively. nCur-mediated PDI@AgNPs@CL treatment showed synergistic effects in clinical isolates and P. aeruginosa ATCC 27853 in a 3-D checkerboard assay. All six of the investigated genes showed down-regulation after nCur-mediated PDI@AgNPs@CL treatment. The most suppressed gene during nCur-mediated PDI@AgNPs@CL treatment was the rhlR gene (-11.9-fold) of P. aeruginosa ATCC 27853. The SEM micrographs further proved the connecting cement reduction and biofilm mass mitigation following nCur-mediated PDI@AgNPs@CL treatments. CONCLUSIONS The combined effect of nCur-mediated PDI and AgNPs@CL synergistically reduce the formation of biofilm in P. aeruginosa. This may be attributable to the suppression of the genes responsible for regulating the production of biofilms.
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Affiliation(s)
- Masoud Azimzadeh
- Department of Microbiology, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Grazia Greco
- Department of Veterinary Medicine, University of Bari Aldo Moro, Bari, Italy
| | - Abbas Farmani
- Dental Research Center, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Maryam Pourhajibagher
- Dental Research Center, Dentistry Research Institute, Tehran University of Medical Sciences, Tehran, Iran.
| | - Amir Taherkhani
- Research Center for Molecular Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Mohammad Yousef Alikhani
- Department of Microbiology, Hamadan University of Medical Sciences, Hamadan, Iran; Infectious Disease Research Center, Hamadan University of Medical Sciences, Hamadan, Iran.
| | - Abbas Bahador
- Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran; Fellowship in Clinical Laboratory Sciences, BioHealth Lab, Tehran, Iran.
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Bollen DP, Reddy KC, Lascarez-Lagunas LI, Kim DH, Colaiácovo MP. Germline mitotic quiescence and cell death are induced in Caenorhabditis elegans by exposure to pathogenic Pseudomonas aeruginosa. Genetics 2024; 226:iyad197. [PMID: 37956057 PMCID: PMC10763535 DOI: 10.1093/genetics/iyad197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 08/08/2023] [Accepted: 11/03/2023] [Indexed: 11/15/2023] Open
Abstract
The impact of exposure to microbial pathogens on animal reproductive capacity and germline physiology is not well understood. The nematode Caenorhabditis elegans is a bacterivore that encounters pathogenic microbes in its natural environment. How pathogenic bacteria affect host reproductive capacity of C. elegans is not well understood. Here, we show that exposure of C. elegans hermaphrodites to the Gram-negative pathogen Pseudomonas aeruginosa causes a marked reduction in brood size with concomitant reduction in the number of nuclei in the germline and gonad size. We define 2 processes that are induced that contribute to the decrease in the number of germ cell nuclei. First, we observe that infection with P. aeruginosa leads to the induction of germ cell apoptosis. Second, we observe that this exposure induces mitotic quiescence in the proliferative zone of the C. elegans gonad. Importantly, these processes appear to be reversible; when animals are removed from the presence of P. aeruginosa, germ cell apoptosis is abated, germ cell nuclei numbers increase, and brood sizes recover. The reversible germline dynamics during exposure to P. aeruginosa may represent an adaptive response to improve survival of progeny and may serve to facilitate resource allocation that promotes survival during pathogen infection.
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Affiliation(s)
- Daniel P Bollen
- Division of Infectious Diseases and Department of Pediatrics, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Kirthi C Reddy
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Molecular Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | | | - Dennis H Kim
- Division of Infectious Diseases and Department of Pediatrics, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Monica P Colaiácovo
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
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Vadakkan K, Ngangbam AK, Sathishkumar K, Rumjit NP, Cheruvathur MK. A review of chemical signaling pathways in the quorum sensing circuit of Pseudomonas aeruginosa. Int J Biol Macromol 2024; 254:127861. [PMID: 37939761 DOI: 10.1016/j.ijbiomac.2023.127861] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Revised: 10/26/2023] [Accepted: 11/01/2023] [Indexed: 11/10/2023]
Abstract
Pseudomonas aeruginosa, an increasingly common competitive and biofilm organism in healthcare infection with sophisticated, interlinked and hierarchic quorum systems (Las, Rhl, PQS, and IQS), creates the greatest threats to the medical industry and has rendered prevailing chemotherapy medications ineffective. The rise of multidrug resistance has evolved into a concerning and potentially fatal occurrence for human life. P. aeruginosa biofilm development is assisted by exopolysaccharides, extracellular DNA, proteins, macromolecules, cellular signaling and interaction. Quorum sensing is a communication process between cells that involves autonomous inducers and regulators. Quorum-induced infectious agent biofilms and the synthesis of virulence factors have increased disease transmission, medication resistance, infection episodes, hospitalizations and mortality. Hence, quorum sensing may be a potential therapeutical target for bacterial illness, and developing quorum inhibitors as an anti-virulent tool could be a promising treatment strategy for existing antibiotics. Quorum quenching is a prevalent technique for treating infections caused by microbes because it diminishes microbial pathogenesis and increases microbe biofilm sensitivity to antibiotics, making it a potential candidate for drug development. This paper examines P. aeruginosa quorum sensing, the hierarchy of quorum sensing mechanism, quorum sensing inhibition and quorum sensing inhibitory agents as a drug development strategy to supplement traditional antibiotic strategies.
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Affiliation(s)
- Kayeen Vadakkan
- Department of Biology, St. Mary's College, Thrissur, Kerala 680020, India; Manipur International University, Imphal, Manipur 795140, India.
| | | | - Kuppusamy Sathishkumar
- Rhizosphere Biology Laboratory, Department of Microbiology, Bharathidasan University, Tiruchirappalli, Tamil Nadu 620024, India; Department of Computational Biology, Institute of Bioinformatics, Saveetha School of Engineering, Saveetha Institute of Medical and Technical Sciences, Thandalam, Chennai 602 105, Tamil Nadu, India
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Tan X, Cheng X, Xiao J, Liu Q, Du D, Li M, Sun Y, Zhou J, Zhu G. Alkaline phosphatase LapA regulates quorum sensing-mediated virulence and biofilm formation in Pseudomonas aeruginosa PAO1 under phosphate depletion stress. Microbiol Spectr 2023; 11:e0206023. [PMID: 37796007 PMCID: PMC10715133 DOI: 10.1128/spectrum.02060-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Accepted: 08/19/2023] [Indexed: 10/06/2023] Open
Abstract
IMPORTANCE Our previous study demonstrated that the expression of lapA was induced under phosphate depletion conditions, but its roles in virulence and biofilm formation by Pseudomonas aeruginosa remain largely unknown. This study presents a systematic investigation of the roles of lapA in virulence induction and biofilm formation by constructing a lapA-deficient strain with P. aeruginosa PAO1. The results showed that deletion of the lapA gene evidently reduced elastase activity, swimming motility, C4-HSL, and 3-oxo-C12-HSL production, and increased rhamnolipid production under phosphate depletion stress. Moreover, lapA gene deletion inhibited PAO1 biofilm formation in porcine skin explants by reducing the expression levels of las and rhl quorum sensing systems and extracellular polymeric substance synthesis. Finally, lapA gene deletion also reduced the virulence of PAO1 in Caenorhabditis elegans in fast-kill and slow-kill infection assays. This study provides insights into the roles of lapA in modulating P. aeruginosa virulence and biofilm formation under phosphate depletion stress.
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Affiliation(s)
- Xiaojuan Tan
- Anhui Provincial Key Laboratory of Molecular Enzymology and Mechanism of Major Diseases, College of Life Sciences, Anhui Normal University, Wuhu, Anhui, China
| | - Xi Cheng
- Anhui Provincial Key Laboratory of Molecular Enzymology and Mechanism of Major Diseases, College of Life Sciences, Anhui Normal University, Wuhu, Anhui, China
| | - Jingjing Xiao
- Anhui Provincial Key Laboratory of Molecular Enzymology and Mechanism of Major Diseases, College of Life Sciences, Anhui Normal University, Wuhu, Anhui, China
| | - Qianqian Liu
- Anhui Provincial Key Laboratory of Molecular Enzymology and Mechanism of Major Diseases, College of Life Sciences, Anhui Normal University, Wuhu, Anhui, China
| | - Dongsheng Du
- Anhui Provincial Key Laboratory of Molecular Enzymology and Mechanism of Major Diseases, College of Life Sciences, Anhui Normal University, Wuhu, Anhui, China
| | - Minghui Li
- Anhui Provincial Key Laboratory of Molecular Enzymology and Mechanism of Major Diseases, College of Life Sciences, Anhui Normal University, Wuhu, Anhui, China
| | - Yang Sun
- Anhui Provincial Key Laboratory of Molecular Enzymology and Mechanism of Major Diseases, College of Life Sciences, Anhui Normal University, Wuhu, Anhui, China
| | - Jinwei Zhou
- School of Food and Biology Engineering, Xuzhou University of Technology, Xuzhou, Jiangsu, China
| | - Guoping Zhu
- Anhui Provincial Key Laboratory of Molecular Enzymology and Mechanism of Major Diseases, College of Life Sciences, Anhui Normal University, Wuhu, Anhui, China
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Simanek KA, Schumacher ML, Mallery CP, Shen S, Li L, Paczkowski JE. Quorum-sensing synthase mutations re-calibrate autoinducer concentrations in clinical isolates of Pseudomonas aeruginosa to enhance pathogenesis. Nat Commun 2023; 14:7986. [PMID: 38042853 PMCID: PMC10693556 DOI: 10.1038/s41467-023-43702-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Accepted: 11/17/2023] [Indexed: 12/04/2023] Open
Abstract
Quorum sensing is a mechanism of bacterial communication that controls virulence gene expression. Pseudomonas aeruginosa regulates virulence via two synthase/transcription factor receptor pairs: LasI/R and RhlI/R. LasR is considered the master transcriptional regulator of quorum sensing, as it upregulates rhlI/R. However, clinical isolates often have inactivating mutations in lasR, while maintaining Rhl-dependent signaling. We sought to understand how quorum sensing progresses in isolates with lasR mutations, specifically via activation of RhlR. We find that clinical isolates with lasR inactivating mutations often harbor concurrent mutations in rhlI. Using ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry, we discover that strains lacking lasR overproduce the RhlI-synthesized autoinducer and that RhlI variants re-calibrate autoinducer concentrations to wild-type levels, restoring virulent phenotypes. These findings provide a mechanism for the plasticity of quorum sensing progression in an acute infection niche.
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Affiliation(s)
- Kayla A Simanek
- Department of Biomedical Sciences, University at Albany, School of Public Health, Albany, New York, 12201, USA
| | - Megan L Schumacher
- Department of Biomedical Sciences, University at Albany, School of Public Health, Albany, New York, 12201, USA
| | - Caleb P Mallery
- Department of Biomedical Sciences, University at Albany, School of Public Health, Albany, New York, 12201, USA
| | - Stella Shen
- Division of Genetics, Wadsworth Center, New York State Department of Health, Albany, New York, 12208, USA
| | - Lingyun Li
- Division of Environmental Health Sciences, Wadsworth Center, New York State Department of Health, Albany, New York, 12208, USA
| | - Jon E Paczkowski
- Department of Biomedical Sciences, University at Albany, School of Public Health, Albany, New York, 12201, USA.
- Division of Genetics, Wadsworth Center, New York State Department of Health, Albany, New York, 12208, USA.
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Keegan NR, Colón Torres NJ, Stringer AM, Prager LI, Brockley MW, McManaman CL, Wade JT, Paczkowski JE. Promoter selectivity of the RhlR quorum-sensing transcription factor receptor in Pseudomonas aeruginosa is coordinated by distinct and overlapping dependencies on C4-homoserine lactone and PqsE. PLoS Genet 2023; 19:e1010900. [PMID: 38064526 PMCID: PMC10732425 DOI: 10.1371/journal.pgen.1010900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 12/20/2023] [Accepted: 11/21/2023] [Indexed: 12/21/2023] Open
Abstract
Quorum sensing is a mechanism of bacterial cell-cell communication that relies on the production and detection of small molecule autoinducers, which facilitate the synchronous expression of genes involved in group behaviors, such as virulence factor production and biofilm formation. The Pseudomonas aeruginosa quorum sensing network consists of multiple interconnected transcriptional regulators, with the transcription factor, RhlR, acting as one of the main drivers of quorum sensing behaviors. RhlR is a LuxR-type transcription factor that regulates its target genes when bound to its cognate autoinducer, C4-homoserine lactone, which is synthesized by RhlI. RhlR function is also regulated by the metallo-β-hydrolase enzyme, PqsE. We recently showed that PqsE binds RhlR to alter its affinity for promoter DNA, a new mechanism of quorum-sensing receptor activation. Here, we perform ChIP-seq analyses of RhlR to map the binding of RhlR across the P. aeruginosa genome, and to determine the impact of C4-homoserine lactone and PqsE on RhlR binding to different sites across the P. aeruginosa genome. We identify 40 RhlR binding sites, all but three of which are associated with genes known to be regulated by RhlR. C4-homoserine lactone is required for maximal binding of RhlR to many of its DNA sites. Moreover, C4-homoserine lactone is required for maximal RhlR-dependent transcription activation from all sites, regardless of whether it impacts RhlR binding to DNA. PqsE is required for maximal binding of RhlR to many DNA sites, with similar effects on RhlR-dependent transcription activation from those sites. However, the effects of PqsE on RhlR specificity are distinct from those of C4-homoserine lactone, and PqsE is sufficient for RhlR binding to some DNA sites in the absence of C4-homoserine lactone. Together, C4-homoserine lactone and PqsE are required for RhlR binding at the large majority of its DNA sites. Thus, our work reveals three distinct modes of activation by RhlR: i) when RhlR is unbound by autoinducer but bound by PqsE, ii) when RhlR is bound by autoinducer but not bound by PqsE, and iii) when RhlR is bound by both autoinducer and PqsE, establishing a stepwise mechanism for the progression of the RhlR-RhlI-PqsE quorum sensing pathway in P. aeruginosa.
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Affiliation(s)
- Nicholas R. Keegan
- Department of Biomedical Sciences, University at Albany, School of Public Health, Albany, New York, United States of America
| | - Nathalie J. Colón Torres
- Division of Genetics, Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
| | - Anne M. Stringer
- Division of Genetics, Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
| | - Lia I. Prager
- Division of Genetics, Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
- Department of Biological Sciences, University at Albany, Albany, New York, United States of America
| | - Matthew W. Brockley
- Division of Genetics, Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
- Department of Biological Sciences, University at Albany, Albany, New York, United States of America
| | - Charity L. McManaman
- Department of Biomedical Sciences, University at Albany, School of Public Health, Albany, New York, United States of America
| | - Joseph T. Wade
- Department of Biomedical Sciences, University at Albany, School of Public Health, Albany, New York, United States of America
- Division of Genetics, Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
| | - Jon E. Paczkowski
- Department of Biomedical Sciences, University at Albany, School of Public Health, Albany, New York, United States of America
- Division of Genetics, Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
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12
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Bayat M, Nahand JS, Farsad-Akhatr N, Memar MY. Bile effects on the Pseudomonas aeruginosa pathogenesis in cystic fibrosis patients with gastroesophageal reflux. Heliyon 2023; 9:e22111. [PMID: 38034726 PMCID: PMC10685303 DOI: 10.1016/j.heliyon.2023.e22111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 09/10/2023] [Accepted: 11/05/2023] [Indexed: 12/02/2023] Open
Abstract
Gastroesophageal reflux (GER) occurs in most cystic fibrosis (CF) patients and is the primary source of bile aspiration in the airway tract of CF individuals. Aspirated bile is associated with the severity of lung diseases and chronic inflammation caused by Pseudomonas aeruginosa as the most common pathogen of CF respiratory tract infections. P. aeruginosa is equipped with several mechanisms to facilitate the infection process, including but not limited to the expression of virulence factors, biofilm formation, and antimicrobial resistance, all of which are under the strong regulation of quorum sensing (QS) mechanism. By increasing the expression of lasI, rhlI, and pqsA-E, bile exposure directly impacts the QS network. An increase in psl expression and pyocyanin production can promote biofilm formation. Along with the loss of flagella and reduced swarming motility, GER-derived bile can repress the expression of genes involved in creating an acute infection, such as expression of Type Three Secretion (T3SS), hydrogen cyanide (hcnABC), amidase (amiR), and phenazine (phzA-E). Inversely, to cause persistent infection, bile exposure can increase the Type Six Secretion System (T6SS) and efflux pump expression, which can trigger resistance to antibiotics such as colistin, polymyxin B, and erythromycin. This review will discuss the influence of aspirated bile on the pathogenesis, resistance, and persistence of P. aeruginosa in CF patients.
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Affiliation(s)
- Mobina Bayat
- Department of Plant, Cell and Molecular Biology, Faculty of Natural Sciences, University of Tabriz, Tabriz, Iran
| | - Javid Sadri Nahand
- Infectious and Tropical Diseases Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Nader Farsad-Akhatr
- Department of Plant, Cell and Molecular Biology, Faculty of Natural Sciences, University of Tabriz, Tabriz, Iran
| | - Mohammad Yousef Memar
- Infectious and Tropical Diseases Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
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13
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Imon RR, Kabir Talukder ME, Akhter S, Islam MS, Ahammad F, Anis-Ul-Haque KM, Moniruzzaman M, Afroze M, Khan M, Hena Mostofa Jamal MA, Wani TA, Uddin MJ, Rahman MM. Natural defense against multi-drug resistant Pseudomonas aeruginosa: Cassia occidentalis L. in vitro and in silico antibacterial activity. RSC Adv 2023; 13:28773-28784. [PMID: 37790109 PMCID: PMC10543200 DOI: 10.1039/d3ra03923d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 09/11/2023] [Indexed: 10/05/2023] Open
Abstract
Cassia occidentalis L. is widely used in indigenous and traditional medicine, but its impact on multi-drug resistant (MDR) bacterial infections mostly remains unknown. Therefore, this study aimed to evaluate the in vitro antibacterial efficiency of methanol and ethyl acetate extracts of C. occidentalis L. leaves (MECOL and EAECOL) against multi-drug resistant Pseudomonas aeruginosa and to identify potential antibacterial agents through computational studies targeting the LasR protein. Initially, 82 compounds were identified using GC-MS analysis, and the functional groups were determined through FT-IR analysis. Both extracts of the plant exhibited dose-dependent antibacterial activity, with MICs of 104.16 ± 36.08 μg mL-1 for MECOL and 83.33 ± 36.08 μg mL-1 for EAECOL, and an MBC of 125 μg mL-1. Among the 82 compounds, 12 potential compounds were identified based on binding scores using molecular docking with the LasR protein and MM-GBSA analysis. Furthermore, screening for ADME properties, including physicochemical features, water solubility, lipophilicity, RO5 compliance, and toxicity, identified the top three compounds: methyl dihydrojasmonate, methyl benzoate, and 4a-methyl-4,4a,5,6,7,8-hexahydro-2(3H)-naphthalenone, which also demonstrated binding affinity with the active site residues of the LpxC protein of the bacteria. Additionally, molecular dynamics (MD) simulations confirmed the binding reliability of these three phytochemicals to LasR's active pocket, comparable to the protein native inhibitory ligands (C12-HSL). The study offers scientific support for the traditional use of C. occidentalis in treating bacterial infections, highlighting the potential of the three compounds as leads for developing LasR inhibitors to combat multi-drug resistant P. aeruginosa.
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Affiliation(s)
- Raihan Rahman Imon
- Molecular and Cellular Biology Laboratory, Department of Genetic Engineering and Biotechnology, Jashore University of Science and Technology Jashore 7408 Bangladesh
| | - Md Enamul Kabir Talukder
- Molecular and Cellular Biology Laboratory, Department of Genetic Engineering and Biotechnology, Jashore University of Science and Technology Jashore 7408 Bangladesh
| | - Shahina Akhter
- Department of Biochemistry and Biotechnology, University of Science and Technology Chittagong Foy's Lake Chittagong 4202 Bangladesh
| | - Md Saidul Islam
- Korea Institute of Radiological & Medical Sciences 75, Nowon-ro, Nowon-gu Seoul South Korea
| | - Foysal Ahammad
- Laboratory of Computational Biology, Biological Solution Centre (BioSol Centre) Jashore 7408 Bangladesh
- Division of Biological and Biomedical Sciences (BBS), College of Health & Life Sciences (CHLS), Hamad Bin Khalifa University (HBKU) Doha Qatar
| | - K M Anis-Ul-Haque
- Department of Chemistry, Jashore University of Science and Technology Jashore 7408 Bangladesh
| | - Md Moniruzzaman
- Bangladesh Reference Institute for Chemical Measurements (BRICM), Bangladesh Council of Scientific and Industrial Research Dr Qudrat-i-Khuda Road, Dhanmondi Dhaka 1205 Bangladesh
| | - Mirola Afroze
- Bangladesh Reference Institute for Chemical Measurements (BRICM), Bangladesh Council of Scientific and Industrial Research Dr Qudrat-i-Khuda Road, Dhanmondi Dhaka 1205 Bangladesh
| | - Mala Khan
- Bangladesh Reference Institute for Chemical Measurements (BRICM), Bangladesh Council of Scientific and Industrial Research Dr Qudrat-i-Khuda Road, Dhanmondi Dhaka 1205 Bangladesh
| | | | - Tanveer A Wani
- Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University PO Box 2457 Riyadh 11451 Saudi Arabia
| | - Mohammad Jashim Uddin
- Department of Pharmacy, Jashore University of Science and Technology Jashore 7408 Bangladesh
| | - Md Mashiar Rahman
- Molecular and Cellular Biology Laboratory, Department of Genetic Engineering and Biotechnology, Jashore University of Science and Technology Jashore 7408 Bangladesh
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14
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Ghosh M, Raghav S, Ghosh P, Maity S, Mohela K, Jain D. Structural analysis of novel drug targets for mitigation of Pseudomonas aeruginosa biofilms. FEMS Microbiol Rev 2023; 47:fuad054. [PMID: 37771093 DOI: 10.1093/femsre/fuad054] [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: 05/30/2023] [Revised: 09/20/2023] [Accepted: 09/27/2023] [Indexed: 09/30/2023] Open
Abstract
Pseudomonas aeruginosa is an opportunistic human pathogen responsible for acute and chronic, hard to treat infections. Persistence of P. aeruginosa is due to its ability to develop into biofilms, which are sessile bacterial communities adhered to substratum and encapsulated in layers of self-produced exopolysaccharides. These biofilms provide enhanced protection from the host immune system and resilience towards antibiotics, which poses a challenge for treatment. Various strategies have been expended for combating biofilms, which involve inhibiting biofilm formation or promoting their dispersal. The current remediation approaches offer some hope for clinical usage, however, treatment and eradication of preformed biofilms is still a challenge. Thus, identifying novel targets and understanding the detailed mechanism of biofilm regulation becomes imperative. Structure-based drug discovery (SBDD) provides a powerful tool that exploits the knowledge of atomic resolution details of the targets to search for high affinity ligands. This review describes the available structural information on the putative target protein structures that can be utilized for high throughput in silico drug discovery against P. aeruginosa biofilms. Integrating available structural information on the target proteins in readily accessible format will accelerate the process of drug discovery.
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Affiliation(s)
- Moumita Ghosh
- Transcription Regulation Lab, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone, Faridabad-Gurugram Expressway, Faridabad, Haryana-121001, India
| | - Shikha Raghav
- Transcription Regulation Lab, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone, Faridabad-Gurugram Expressway, Faridabad, Haryana-121001, India
| | - Puja Ghosh
- Transcription Regulation Lab, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone, Faridabad-Gurugram Expressway, Faridabad, Haryana-121001, India
| | - Swagatam Maity
- Transcription Regulation Lab, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone, Faridabad-Gurugram Expressway, Faridabad, Haryana-121001, India
| | - Kavery Mohela
- Transcription Regulation Lab, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone, Faridabad-Gurugram Expressway, Faridabad, Haryana-121001, India
| | - Deepti Jain
- Transcription Regulation Lab, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone, Faridabad-Gurugram Expressway, Faridabad, Haryana-121001, India
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15
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Ashrafudoulla M, Mevo SIU, Song M, Chowdhury MAH, Shaila S, Kim DH, Nahar S, Toushik SH, Park SH, Ha SD. Antibiofilm mechanism of peppermint essential oil to avert biofilm developed by foodborne and food spoilage pathogens on food contact surfaces. J Food Sci 2023; 88:3935-3955. [PMID: 37477280 DOI: 10.1111/1750-3841.16712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Revised: 06/10/2023] [Accepted: 07/05/2023] [Indexed: 07/22/2023]
Abstract
Establishing efficient methods to combat bacterial biofilms is a major concern. Natural compounds, such as essential oils derived from plants, are among the favored and recommended strategies for combatting bacteria and their biofilm. Therefore, we evaluated the antibiofilm properties of peppermint oil as well as the activities by which it kills bacteria generally and particularly their biofilms. Peppermint oil antagonistic activities were investigated against Vibrio parahaemolyticus, Listeria monocytogenes, Pseudomonas aeruginosa, Escherichia coli O157:H7, and Salmonella Typhimurium on four food contact surfaces (stainless steel, rubber, high-density polyethylene, and polyethylene terephthalate). Biofilm formation on each studied surface, hydrophobicity, autoaggregation, metabolic activity, and adenosine triphosphate quantification were evaluated for each bacterium in the presence and absence (control) of peppermint oil. Real-time polymerase chain reaction, confocal laser scanning microscopy, and field-emission scanning electron microscopy were utilized to analyze the effects of peppermint oil treatment on the bacteria and their biofilm. Results showed that peppermint oil (1/2× minimum inhibitory concentration [MIC], MIC, and 2× MIC) substantially lessened biofilm formation, with high bactericidal properties. A minimum of 2.5-log to a maximum of around 5-log reduction was attained, with the highest sensitivity shown by V. parahaemolyticus. Morphological experiments revealed degradation of the biofilm structure, followed by some dead cells with broken membranes. Thus, this study established the possibility of using peppermint oil to combat key foodborne and food spoilage pathogens in the food processing environment.
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Affiliation(s)
- Md Ashrafudoulla
- Department of Food Science and Technology, Chung-Ang University, Anseong-si, Republic of Korea
| | | | - Minsu Song
- Department of Food Science and Technology, Chung-Ang University, Anseong-si, Republic of Korea
| | | | - Shanjida Shaila
- Department of Food Science and Technology, Chung-Ang University, Anseong-si, Republic of Korea
| | - Duk Hyun Kim
- Department of Food Science and Technology, Chung-Ang University, Anseong-si, Republic of Korea
| | - Shamsun Nahar
- Department of Food Science and Technology, Chung-Ang University, Anseong-si, Republic of Korea
| | - Sazzad Hossen Toushik
- Department of Biochemistry & Microbiology, School of Health & Life Sciences, North South University, Dhaka, Bangladesh
| | - Si Hong Park
- Department of Food Science and Technology, Oregon State University, Corvallis, Oregon, USA
| | - Sang-Do Ha
- Department of Food Science and Technology, Chung-Ang University, Anseong-si, Republic of Korea
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16
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Sánchez-Jiménez A, Llamas MA, Marcos-Torres FJ. Transcriptional Regulators Controlling Virulence in Pseudomonas aeruginosa. Int J Mol Sci 2023; 24:11895. [PMID: 37569271 PMCID: PMC10418997 DOI: 10.3390/ijms241511895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 07/21/2023] [Accepted: 07/22/2023] [Indexed: 08/13/2023] Open
Abstract
Pseudomonas aeruginosa is a pathogen capable of colonizing virtually every human tissue. The host colonization competence and versatility of this pathogen are powered by a wide array of virulence factors necessary in different steps of the infection process. This includes factors involved in bacterial motility and attachment, biofilm formation, the production and secretion of extracellular invasive enzymes and exotoxins, the production of toxic secondary metabolites, and the acquisition of iron. Expression of these virulence factors during infection is tightly regulated, which allows their production only when they are needed. This process optimizes host colonization and virulence. In this work, we review the intricate network of transcriptional regulators that control the expression of virulence factors in P. aeruginosa, including one- and two-component systems and σ factors. Because inhibition of virulence holds promise as a target for new antimicrobials, blocking the regulators that trigger the production of virulence determinants in P. aeruginosa is a promising strategy to fight this clinically relevant pathogen.
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Affiliation(s)
| | - María A. Llamas
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, 18008 Granada, Spain;
| | - Francisco Javier Marcos-Torres
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, 18008 Granada, Spain;
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17
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García-Diéguez L, Diaz-Tang G, Marin Meneses E, Cruise V, Barraza I, Craddock TJ, Smith RP. Periodically disturbing biofilms reduces expression of quorum sensing-regulated virulence factors in Pseudomonas aeruginosa. iScience 2023; 26:106843. [PMID: 37255658 PMCID: PMC10225924 DOI: 10.1016/j.isci.2023.106843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2023] [Revised: 04/26/2023] [Accepted: 05/04/2023] [Indexed: 06/01/2023] Open
Abstract
Pseudomonas aeruginosa uses quorum sensing to regulate the expression of virulence factors. In static environments, spatial structures, such as biofilms, can increase the expression of these virulence factors. However, in natural settings, biofilms are exposed to physical forces that disrupt spatial structure, which may affect the expression of virulence factors regulated by quorum sensing. We show that periodically disturbing biofilms composed of P. aeruginosa using a physical force reduces the expression of quorum sensing-regulated virulence factors. At an intermediate disturbance frequency, the expression of virulence factors in the las, rhl, and pqs regulons is reduced. Mathematical modeling suggests that perturbation of the pqsR receptor is critical for this reduction. Removing the lasR receptor enhances the reduction in the expression of virulence factors as a result of disturbance. Our results allow identification of environments where virulence is reduced and implicate the lasR receptor as having a buffering role against disturbance.
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Affiliation(s)
- Laura García-Diéguez
- Department of Biological Sciences, Halmos College of Arts and Science, Nova Southeastern University, Fort Lauderdale FL 33314, USA
| | - Gabriela Diaz-Tang
- Department of Biological Sciences, Halmos College of Arts and Science, Nova Southeastern University, Fort Lauderdale FL 33314, USA
| | - Estefania Marin Meneses
- Department of Biological Sciences, Halmos College of Arts and Science, Nova Southeastern University, Fort Lauderdale FL 33314, USA
| | - Vanessa Cruise
- Department of Biological Sciences, Halmos College of Arts and Science, Nova Southeastern University, Fort Lauderdale FL 33314, USA
| | - Ivana Barraza
- Department of Biological Sciences, Halmos College of Arts and Science, Nova Southeastern University, Fort Lauderdale FL 33314, USA
| | - Travis J.A. Craddock
- Clinical Systems Biology Group, Institute for Neuro-Immune Medicine, Nova Southeastern University, Fort Lauderdale FL 33314, USA
- Department of Psychology & Neuroscience, College of Psychology, Nova Southeastern University, Fort Lauderdale FL 33314, USA
- Department of Computer Science, College of Engineering and Computing, Nova Southeastern University, Fort Lauderdale FL 33314, USA
- Department of Clinical Immunology, College of Osteopathic Medicine, Nova Southeastern University, Fort Lauderdale FL 33314, USA
| | - Robert P. Smith
- Department of Biological Sciences, Halmos College of Arts and Science, Nova Southeastern University, Fort Lauderdale FL 33314, USA
- Cell Therapy Institute, Kiran Patel College of Allopathic Medicine, Nova Southeastern University, Fort Lauderdale FL 33314, USA
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18
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Miller Conrad LC, Perez LJ. A Geneticist Transcribing the Chemical Language of Bacteria. Isr J Chem 2023; 63:e202200079. [PMID: 37469628 PMCID: PMC10353724 DOI: 10.1002/ijch.202200079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Indexed: 12/05/2022]
Abstract
The study of quorum sensing, bacterial cell-to-cell communication mediated by the production and detection of small molecule signals, has skyrocketed since its discovery in the last third of the 20th century. Building from early investigations of bacterial bioluminescence, the process has been characterized to control a numerous and growing number of group behaviors, including virulence and biofilm formation. Bonnie Bassler has made key contributions to the understanding of quorum sensing, leading interdisciplinary efforts to characterize key signaling pathway components and their respective signaling molecules across a range of gram-negative bacteria. This review highlights her work in the field, with a particular emphasis on the chemical contributions of her work.
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Affiliation(s)
- Laura C. Miller Conrad
- Department of Chemistry, San José State University, 1 Washington Sq, San Jose, CA 95192, USA
| | - Lark J. Perez
- Department of Chemistry & Biochemistry, Rowan University, 201 Mullica Hill Rd, Glassboro, NJ 08028, USA
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19
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Masihzadeh S, Amin M, Farshadzadeh Z. In vitro and in vivo antibiofilm activity of the synthetic antimicrobial peptide WLBU2 against multiple drug resistant Pseudomonas aeruginosa strains. BMC Microbiol 2023; 23:131. [PMID: 37183241 PMCID: PMC10184367 DOI: 10.1186/s12866-023-02886-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Accepted: 05/08/2023] [Indexed: 05/16/2023] Open
Abstract
BACKGROUND The global crisis of antibiotic resistance increases the demand for the novel promising alternative drugs such as antimicrobial peptides (AMPs). Here, the antibiofilm activity of the WLBU2 peptide against Pseudomonas aeruginosa (P. aeruginosa) isolates was investigated in this study. METHODS Two clinical MDR and carbapenem resistant P. aeruginosa (CRPA) isolates, and standard P. aeruginosa ATCC 27,853 were investigated. The MIC and MBC of WLBU2 were determined. The MBIC was determined to evaluate inhibitory activity of WLBU2 on biofilm formation and MBEC to dispersal activity on preformed biofilm. The relative expression levels of biofilm-associated genes including rhlI, rhlR, lasI and lasR were analyzed using RT-qPCR. In vivo evaluation of inhibitory effect of WLBU2 on biofilm formation was performed in the murine models of P. aeruginosa biofilm-associated subcutaneous catheter infection. RESULTS MIC and MBC of WLBU2 for both MDR and ATCC 27,853 P. aeruginosa strains were 8 and 16 µg/mL, respectively, while both the MIC and MBC against the CR strain were 4 µg/mL. MBIC was estimated to be 64 µg/ml for all strains. MBEC against MDR and ATCC 27,853- P. aeruginosa strains was 128 µg/ml and against CRPA was 64 µg/ml. The bacterial adhesion to a static abiotic solid surface (the surface in the polypropylene microtiter wells) was significantly inhibited at 1/4× MIC in all P. aeruginosa strains and at 1/8× MIC in CRPA strain (P < 0.05). Following treatment with WLBU2 at 1/8× MIC, significant inhibition in biofilm formation was observed in all isolates (P < 0.05). Results of the colorimetric assay showed that WLBU2 at 4× MIC was able to disperse 69.7% and 81.3% of pre-formed biofilms on abiotic surface produced by MDR and standard (ATCC 27,853) P. aeruginosa, respectively (P < 0.03), while a 92.2% reduction in the CRPA biofilm was observed after treatment with 4× MIC WLBU2 (P < 0.03). The expression levels of all genes in isolates treated with 1/2 MIC of WLBU2 were down-regulated by more than four-fold compared to the untreated isolates (P < 0.05). WLBU2 significantly inhibited biofilm formation in murine catheter-associated CRPA infection model at 1/4×MIC, 1/2×MIC, and 1×MIC by 33%, 52%, and 67%, respectively. CONCLUSION Considering relatively strong inhibitory and eradication potency of WLBU2 on the P. aeruginosa biofilms in in vitro and in vivo conditions, the peptide can be considered as a promising candidate for designing an antibiofilm drug.
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Affiliation(s)
- Sara Masihzadeh
- Infectious and Tropical Diseases Research Center, Health Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
- Department of Microbiology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Mansour Amin
- Infectious and Tropical Diseases Research Center, Health Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
- Department of Microbiology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Zahra Farshadzadeh
- Infectious and Tropical Diseases Research Center, Health Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.
- Department of Microbiology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.
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20
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Peterson ND, Tse SY, Huang QJ, Wani KA, Schiffer CA, Pukkila-Worley R. Non-canonical pattern recognition of a pathogen-derived metabolite by a nuclear hormone receptor identifies virulent bacteria in C. elegans. Immunity 2023; 56:768-782.e9. [PMID: 36804958 PMCID: PMC10101930 DOI: 10.1016/j.immuni.2023.01.027] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 11/27/2022] [Accepted: 01/25/2023] [Indexed: 02/19/2023]
Abstract
Distinguishing infectious pathogens from harmless microorganisms is essential for animal health. The mechanisms used to identify infectious microbes are not fully understood, particularly in metazoan hosts that eat bacteria as their food source. Here, we characterized a non-canonical pattern-recognition system in Caenorhabditis elegans (C. elegans) that assesses the relative threat of virulent Pseudomonas aeruginosa (P. aeruginosa) to activate innate immunity. We discovered that the innate immune response in C. elegans was triggered by phenazine-1-carboxamide (PCN), a toxic metabolite produced by pathogenic strains of P. aeruginosa. We identified the nuclear hormone receptor NHR-86/HNF4 as the PCN sensor in C. elegans and validated that PCN bound to the ligand-binding domain of NHR-86/HNF4. Activation of NHR-86/HNF4 by PCN directly engaged a transcriptional program in intestinal epithelial cells that protected against P. aeruginosa. Thus, a bacterial metabolite is a pattern of pathogenesis surveilled by nematodes to identify a pathogen in its bacterial diet.
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Affiliation(s)
- Nicholas D Peterson
- Program in Innate Immunity, Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Samantha Y Tse
- Program in Innate Immunity, Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Qiuyu Judy Huang
- Department of Biochemistry and Molecular Biotechnology, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Khursheed A Wani
- Program in Innate Immunity, Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Celia A Schiffer
- Department of Biochemistry and Molecular Biotechnology, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Read Pukkila-Worley
- Program in Innate Immunity, Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Chan Medical School, Worcester, MA, USA.
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21
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Memariani H, Memariani M. Antibiofilm properties of cathelicidin LL-37: an in-depth review. World J Microbiol Biotechnol 2023; 39:99. [PMID: 36781570 DOI: 10.1007/s11274-023-03545-z] [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: 12/17/2022] [Accepted: 02/08/2023] [Indexed: 02/15/2023]
Abstract
Notwithstanding ceaseless endeavors toward developing effective antibiofilm chemotherapeutics, biofilm-associated infections continue to be one of the most perplexing challenges confronting medicine today. Endogenous host defense peptides, such as the human cathelicidin LL-37, are being propounded as promising options for treating such infectious diseases. Over the past decennium, LL-37 has duly received tremendous research attention by virtue of its broad-spectrum antimicrobial activity and immunomodulatory properties. No attempt has hitherto been made, as far as we are aware, to comprehensively review the antibiofilm effects of LL-37. Accordingly, the intent in this paper is to provide a fairly all-embracing review of the literature available on the subject. Accumulating evidence suggests that LL-37 is able to prevent biofilm establishment by different bacterial pathogens such as Acinetobacter baumannii, Aggregatibacter actinomycetemcomitans, Bacteroides fragilis, Burkholderia thailandensis, Cutibacterium acnes, Escherichia coli, Francisella tularensis, Helicobacter pylori, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, and Streptococcus pyogenes. Inhibition of bacterial adhesion, downregulation of biofilm-associated genes, suppression of quorum-sensing pathways, degradation of biofilm matrix, and eradication of biofilm-residing cells are the major mechanisms responsible for antibiofilm properties of LL-37. In terms of its efficacy and safety in vivo, there are still many questions to be answered. Undoubtedly, LL-37 can open up new windows of opportunity to prevent and treat obstinate biofilm-mediated infections.
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Affiliation(s)
- Hamed Memariani
- Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Mojtaba Memariani
- Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran.
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22
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Jeon Y, Baranwal P, Li L, Piezer K, Seo Y. Review: Current understanding on biological filtration for the removal of microcystins. CHEMOSPHERE 2023; 313:137160. [PMID: 36356807 DOI: 10.1016/j.chemosphere.2022.137160] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 10/10/2022] [Accepted: 10/30/2022] [Indexed: 06/16/2023]
Abstract
Harmful algal blooms (HABs) have become a global problem not only in aquatic habitats but also in public health and safety due to the production of cyanotoxins as their secondary metabolites. Among the various identified cyanotoxin groups, microcystins (MCs) are one of the most prevalent cyanotoxin detected during HABs. Different strategies including advanced physical and chemical treatment processes have been developed to mitigate the threat of cyanotoxins in water utilities, but these have revealed certain limitations in terms of high operational costs, low removal efficacy, and harmful by-products formation. Recently, biological filtration systems (BFS) have gained attention for safe drinking water production as they can treat various natural organic matter (NOM) and emerging contaminants through a highly efficient and environmentally sustainable process. However, limited attention has been given to understand the current research progress, research challenges, and knowledge gaps for the successful implementation of BFS for MC removal. Therefore, in this review, currently identified MC biodegradation pathways and MC-degrading microorganisms with their degradation rates are summarized, which may be pivotal for studying bioaugmented BFS to enhance the MC removal during HABs. Moreover, both laboratory and field studies on BFS for MC removal are reviewed, followed by a discussion of current challenges and future research needs for the practical application of BFS.
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Affiliation(s)
- Youchul Jeon
- Department of Civil and Environmental Engineering, University of Toledo, Mail Stop 307, 3006 Nitschke Hall, Toledo, OH, 43606, United States
| | - Parul Baranwal
- Department of Civil and Environmental Engineering, University of Toledo, Mail Stop 307, 3006 Nitschke Hall, Toledo, OH, 43606, United States
| | - Lei Li
- Department of Civil and Environmental Engineering, University of Toledo, Mail Stop 307, 3006 Nitschke Hall, Toledo, OH, 43606, United States
| | - Kayla Piezer
- Department of Civil and Environmental Engineering, University of Toledo, Mail Stop 307, 3006 Nitschke Hall, Toledo, OH, 43606, United States; Department of Chemical Engineering, University of Toledo, Mail Stop 307, 3048 Nitschke Hall, Toledo, OH, 43606, United States
| | - Youngwoo Seo
- Department of Civil and Environmental Engineering, University of Toledo, Mail Stop 307, 3006 Nitschke Hall, Toledo, OH, 43606, United States; Department of Chemical Engineering, University of Toledo, Mail Stop 307, 3048 Nitschke Hall, Toledo, OH, 43606, United States.
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23
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Nyanasegran PK, Nathan S, Firdaus-Raih M, Muhammad NAN, Ng CL. Biofilm Signaling, Composition and Regulation in Burkholderia pseudomallei. J Microbiol Biotechnol 2023; 33:15-27. [PMID: 36451302 PMCID: PMC9899790 DOI: 10.4014/jmb.2207.07032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 10/10/2022] [Accepted: 10/11/2022] [Indexed: 12/04/2022]
Abstract
The incidence of melioidosis cases caused by the gram-negative pathogen Burkholderia pseudomallei (BP) is seeing an increasing trend that has spread beyond its previously known endemic regions. Biofilms produced by BP have been associated with antimicrobial therapy limitation and relapse melioidosis, thus making it urgently necessary to understand the mechanisms of biofilm formation and their role in BP biology. Microbial cells aggregate and enclose within a self-produced matrix of extracellular polymeric substances (EPSs) to form biofilm. The transition mechanism of bacterial cells from planktonic state to initiate biofilm formation, which involves the formation of surface attachment microcolonies and the maturation of the biofilm matrix, is a dynamic and complex process. Despite the emerging findings on the biofilm formation process, systemic knowledge on the molecular mechanisms of biofilm formation in BP remains fractured. This review provides insights into the signaling systems, matrix composition, and the biosynthesis regulation of EPSs (exopolysaccharide, eDNA and proteins) that facilitate the formation of biofilms in order to present an overview of our current knowledge and the questions that remain regarding BP biofilms.
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Affiliation(s)
| | - Sheila Nathan
- Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia
| | - Mohd Firdaus-Raih
- Institute of Systems Biology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia,Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia
| | - Nor Azlan Nor Muhammad
- Institute of Systems Biology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia
| | - Chyan Leong Ng
- Institute of Systems Biology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia,Corresponding author Phone: +03 8921 4561 Fax: +603 8921 3398 E-mail:
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24
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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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25
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Feathers JR, Richael EK, Simanek KA, Fromme JC, Paczkowski JE. Structure of the RhlR-PqsE complex from Pseudomonas aeruginosa reveals mechanistic insights into quorum-sensing gene regulation. Structure 2022; 30:1626-1636.e4. [PMID: 36379213 PMCID: PMC9722607 DOI: 10.1016/j.str.2022.10.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 08/26/2022] [Accepted: 10/20/2022] [Indexed: 11/16/2022]
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen that is responsible for thousands of deaths every year in the United States. P. aeruginosa virulence factor production is mediated by quorum sensing, a mechanism of bacterial cell-cell communication that relies on the production and detection of signal molecules called autoinducers. In P. aeruginosa, the transcription factor receptor RhlR is activated by a RhlI-synthesized autoinducer. We recently showed that RhlR-dependent transcription is enhanced by a physical interaction with the enzyme PqsE via increased affinity of RhlR for promoter DNA. However, the molecular basis for complex formation and how complex formation enhanced RhlR transcriptional activity remained unclear. Here, we report the structure of ligand-bound RhlR in complex with PqsE. Additionally, we determined the structure of the complex bound with DNA, revealing the mechanism by which RhlR-mediated transcription is enhanced by PqsE, thereby establishing the molecular basis for RhlR-dependent virulence factor production in P. aeruginosa.
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Affiliation(s)
- J Ryan Feathers
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA
| | - Erica K Richael
- Division of Genetics, Wadsworth Center, New York State Department of Health, Albany, NY 12208, USA
| | - Kayla A Simanek
- Department of Biomedical Sciences, University at Albany, School of Public Health, Albany, NY 12201, USA
| | - J Christopher Fromme
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA
| | - Jon E Paczkowski
- Division of Genetics, Wadsworth Center, New York State Department of Health, Albany, NY 12208, USA; Department of Biomedical Sciences, University at Albany, School of Public Health, Albany, NY 12201, USA.
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26
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Borgert SR, Henke S, Witzgall F, Schmelz S, Zur Lage S, Hotop SK, Stephen S, Lübken D, Krüger J, Gomez NO, van Ham M, Jänsch L, Kalesse M, Pich A, Brönstrup M, Häussler S, Blankenfeldt W. Moonlighting chaperone activity of the enzyme PqsE contributes to RhlR-controlled virulence of Pseudomonas aeruginosa. Nat Commun 2022; 13:7402. [PMID: 36456567 PMCID: PMC9715718 DOI: 10.1038/s41467-022-35030-w] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 11/14/2022] [Indexed: 12/05/2022] Open
Abstract
Pseudomonas aeruginosa is a major cause of nosocomial infections and also leads to severe exacerbations in cystic fibrosis or chronic obstructive pulmonary disease. Three intertwined quorum sensing systems control virulence of P. aeruginosa, with the rhl circuit playing the leading role in late and chronic infections. The majority of traits controlled by rhl transcription factor RhlR depend on PqsE, a dispensable thioesterase in Pseudomonas Quinolone Signal (PQS) biosynthesis that interferes with RhlR through an enigmatic mechanism likely involving direct interaction of both proteins. Here we show that PqsE and RhlR form a 2:2 protein complex that, together with RhlR agonist N-butanoyl-L-homoserine lactone (C4-HSL), solubilizes RhlR and thereby renders the otherwise insoluble transcription factor active. We determine crystal structures of the complex and identify residues essential for the interaction. To corroborate the chaperone-like activity of PqsE, we design stability-optimized variants of RhlR that bypass the need for C4-HSL and PqsE in activating PqsE/RhlR-controlled processes of P. aeruginosa. Together, our data provide insight into the unique regulatory role of PqsE and lay groundwork for developing new P. aeruginosa-specific pharmaceuticals.
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Affiliation(s)
- Sebastian Roman Borgert
- Department Structure and Function of Proteins, Helmholtz Centre for Infection Research, Inhoffenstr. 7, 38124, Braunschweig, Germany
| | - Steffi Henke
- Department Structure and Function of Proteins, Helmholtz Centre for Infection Research, Inhoffenstr. 7, 38124, Braunschweig, Germany
| | - Florian Witzgall
- Department Structure and Function of Proteins, Helmholtz Centre for Infection Research, Inhoffenstr. 7, 38124, Braunschweig, Germany
| | - Stefan Schmelz
- Department Structure and Function of Proteins, Helmholtz Centre for Infection Research, Inhoffenstr. 7, 38124, Braunschweig, Germany
| | - Susanne Zur Lage
- Department Structure and Function of Proteins, Helmholtz Centre for Infection Research, Inhoffenstr. 7, 38124, Braunschweig, Germany
| | - Sven-Kevin Hotop
- Department Chemical Biology, Helmholtz Centre for Infection Research, Inhoffenstr. 7, 38124, Braunschweig, Germany
| | - Steffi Stephen
- Department Chemical Biology, Helmholtz Centre for Infection Research, Inhoffenstr. 7, 38124, Braunschweig, Germany
| | - Dennis Lübken
- Institute of Organic Chemistry, Leibniz University Hannover, Schneiderberg 1B, 30167, Hannover, Germany
| | - Jonas Krüger
- Department Molecular Bacteriology, Helmholtz Centre for Infection Research, Inhoffenstr. 7, 38124, Braunschweig, Germany
| | - Nicolas Oswaldo Gomez
- Department Molecular Bacteriology, Helmholtz Centre for Infection Research, Inhoffenstr. 7, 38124, Braunschweig, Germany
| | - Marco van Ham
- Cellular Proteomics, Helmholtz Centre for Infection Research, Inhoffenstr. 7, 38124, Braunschweig, Germany
| | - Lothar Jänsch
- Cellular Proteomics, Helmholtz Centre for Infection Research, Inhoffenstr. 7, 38124, Braunschweig, Germany
| | - Markus Kalesse
- Institute of Organic Chemistry, Leibniz University Hannover, Schneiderberg 1B, 30167, Hannover, Germany
| | - Andreas Pich
- Institute for Toxicology, Core Facility Proteomics, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany
| | - Mark Brönstrup
- Department Chemical Biology, Helmholtz Centre for Infection Research, Inhoffenstr. 7, 38124, Braunschweig, Germany
| | - Susanne Häussler
- Department Molecular Bacteriology, Helmholtz Centre for Infection Research, Inhoffenstr. 7, 38124, Braunschweig, Germany
| | - Wulf Blankenfeldt
- Department Structure and Function of Proteins, Helmholtz Centre for Infection Research, Inhoffenstr. 7, 38124, Braunschweig, Germany.
- Institute for Biochemistry, Biotechnology and Bioinformatics, Technische Universität Braunschweig, Spielmannstr. 7, 38106, Braunschweig, Germany.
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27
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Kasthuri T, Barath S, Nandhakumar M, Karutha Pandian S. Proteomic profiling spotlights the molecular targets and the impact of the natural antivirulent umbelliferone on stress response, virulence factors, and the quorum sensing network of Pseudomonas aeruginosa. Front Cell Infect Microbiol 2022; 12:998540. [PMID: 36530435 PMCID: PMC9748083 DOI: 10.3389/fcimb.2022.998540] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 10/18/2022] [Indexed: 12/05/2022] Open
Abstract
Pseudomonas aeruginosa easily adapts to newer environments and acquires several genome flexibilities to overcome the effect of antibiotics during therapeutics, especially in cystic fibrosis patients. During adaptation to the host system, the bacteria employ various tactics including virulence factor production and biofilm formation to escape from the host immune system and resist antibiotics. Hence, identifying alternative strategies to combat recalcitrant pathogens is imperative for the successful elimination of drug-resistant microbes. In this context, this study portrays the anti-virulence efficacy of umbelliferone (UMB) against P. aeruginosa. UMB (7-hydroxy coumarin) is pervasively found among the plant family of Umbelliferae and Asteraceae. The UMB impeded biofilm formation in the P. aeruginosa reference strain and clinical isolates on polystyrene and glass surfaces at the concentration of 125 µg/ml. Global proteomic analysis of UMB-treated cells revealed the downregulation of major virulence-associated proteins such as RhlR, LasA, AlgL, FliD, Tpx, HtpG, KatA, FusA1, Tsf, PhzM, PhzB2, CarB, DctP, MtnA, and MscL. A functional interaction study, gene ontology, and KEGG pathway analysis revealed that UMB could modulate the global regulators, enzymes, co-factors, and transcription factors related to quorum sensing (QS), stress tolerance, siderophore production, motility, and microcolony formation. In vitro biochemical assays further affirmed the anti-virulence efficacy of UMB by reducing pyocyanin, protease, elastase, and catalase production in various strains of P. aeruginosa. Besides the antibiofilm activity, UMB-treated cells exhibited enhanced antibiotic susceptibility to various antibiotics including amikacin, kanamycin, tobramycin, ciprofloxacin, and cefotaxime. Furthermore, in vitro cytotoxicity analysis revealed the biocompatibility of UMB, and the IC50 value was determined to be 249.85 µg/ml on the HepG2 cell line. Altogether, the study substantiates the anti-virulence efficacy of UMB against P. aeruginosa, and the proteomic analysis reveals the differential expression of the regulators related to QS, stress response, and motility factors.
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28
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Han X, Nan M, Cai X, Qiao B, Chen L, Shen L. Sennoside A inhibits quorum sensing system to attenuate its regulated virulence and pathogenicity via targeting LasR in Pseudomonas aeruginosa. Front Microbiol 2022; 13:1042214. [DOI: 10.3389/fmicb.2022.1042214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Accepted: 10/12/2022] [Indexed: 11/06/2022] Open
Abstract
Pseudomonas aeruginosa is an important opportunistic pathogen, and the emergence of drug resistance greatly increased the difficulty of treating its infection. Cell density-dependent quorum sensing (QS) system not only regulates the virulence but also associates with the drug resistance of P. aeruginosa. Screening for agents targeting QS to inhibit bacterial virulence and pathogenicity is considered a promising strategy to combat P. aeruginosa infection. In the present study, sennoside A was found to be able to inhibit the QS expression of P. aeruginosa at subinhibitory concentrations. The QS-regulated virulence factors, including protease, elastase, rhamnolipid, and pyocyanin, were also inhibited by sennoside A at both transcriptional and translational levels. Moreover, sennoside A could suppress the motility of twitching, swimming, and swarming as well as the biofilm formation, which is associated with the acute and chronic infections of P. aeruginosa in a dose-dependent manner. The attenuated pathogenicity of P. aeruginosa by sennoside A was further verified by Chinese cabbage, Drosophila melanogaster, and Caenorhabditis elegans infection analysis. Further study found that sennoside A might target the las system, mainly LasR, to interfere with QS. All the results indicate that sennoside A could inhibit the QS system to attenuate its regulated virulence and pathogenicity via mainly targeting LasR in P. aeruginosa and further research to identify its anti-QS activity for other Gram-negative bacteria is warranted.
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29
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Taylor IR, Murray-Nerger LA, Greco TM, Liu D, Cristea IM, Bassler BL. Protein Interaction Networks of Catalytically Active and Catalytically Inactive PqsE in Pseudomonas aeruginosa. mBio 2022; 13:e0155922. [PMID: 36073810 PMCID: PMC9600345 DOI: 10.1128/mbio.01559-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Accepted: 08/11/2022] [Indexed: 11/24/2022] Open
Abstract
Pseudomonas aeruginosa is a human pathogen that relies on quorum sensing to establish infections. The PqsE quorum-sensing protein is required for P. aeruginosa virulence factor production and infection. PqsE has a reported enzymatic function in the biosynthesis of the quorum-sensing autoinducer called PQS. However, this activity is redundant because, in the absence of PqsE, this role is fulfilled by alternative thioesterases. Rather, PqsE drives P. aeruginosa pathogenic traits via a protein-protein interaction with the quorum-sensing receptor/transcription factor RhlR, an interaction that enhances the affinity of RhlR for target DNA sequences. PqsE catalytic activity is dispensable for interaction with RhlR. Thus, the virulence function of PqsE can be decoupled from its catalytic function. Here, we present an immunoprecipitation-mass spectrometry method employing enhanced green fluorescent protein-PqsE fusions to define the protein interactomes of wild-type PqsE and the catalytically inactive PqsE(D73A) variant in P. aeruginosa and their dependence on RhlR. Several proteins were identified to have specific interactions with wild-type PqsE while not forming associations with PqsE(D73A). In the ΔrhlR strain, an increased number of specific PqsE interactors were identified, including the partner autoinducer synthase for RhlR, called RhlI. Collectively, these results suggest that specific protein-protein interactions depend on PqsE catalytic activity and that RhlR may prevent proteins from interacting with PqsE, possibly due to competition between RhlR and other proteins for PqsE binding. Our results provide a foundation for the identification of the in vivo PqsE catalytic function and, potentially, new proteins involved in P. aeruginosa quorum sensing. IMPORTANCE Pseudomonas aeruginosa causes hospital-borne infections in vulnerable patients, including immunocompromised individuals, burn victims, and cancer patients undergoing chemotherapy. There are no effective treatments for P. aeruginosa infections, which are usually broadly resistant to antibiotics. Animal models show that, to establish infection and to cause illness, P. aeruginosa relies on an interaction between two proteins, namely, PqsE and RhlR. There could be additional protein-protein interactions involving PqsE, which, if defined, could be exploited for the design of new therapeutic strategies to combat P. aeruginosa. Here, we reveal previously unknown protein interactions in which PqsE participates, which will be investigated for potential roles in pathogenesis.
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Affiliation(s)
- Isabelle R. Taylor
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA
| | | | - Todd M. Greco
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA
| | - Dawei Liu
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA
| | - Ileana M. Cristea
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA
| | - Bonnie L. Bassler
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA
- Howard Hughes Medical Institute, Chevy Chase, Maryland, USA
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30
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Shakour N, Taheri E, Rajabian F, Tarighi S, Soheili V, Hadizadeh F. Evaluating the Antivirulence Effects of New Thiazolidinedione Compounds Against Pseudomonas aeruginosa PAO1. Microb Drug Resist 2022; 28:1003-1018. [PMID: 36219761 DOI: 10.1089/mdr.2022.0134] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen that causes several serious health problems and numerous forms of virulence. During the treatment of P. aeruginosa infections, the development of multidrug-resistant isolates creates significant clinical problems. Using antivirulence compounds to disrupt pathogenicity rather than killing the bacterium may be an interesting strategy to overcome this problem, because less harsh conditions will exist for the development of resistance. To reduce pathogenicity and biofilm formation, newly synthesized analogs of imidazolyl (8n) and previously synthesized analogs (8a-8m) with a similar backbone [the 5-(imidazolyl-methyl) thiazolidinediones] were tested against pyoverdine and pyocyanin production, protease activity, and biofilm formation. Compared to the positive control group, the best compounds reduced the production of pyoverdine (8n) by 89.57% and pyocyanin (8i) by 22.68%, and protease activity (8n) by 2.80% for PAO1 strain, at a concentration of 10 μM. Moreover, the biofilm formation assay showed a reduction of 87.94% (8i) for PAO1, as well as 30.53% (8d) and 44.65% (8m) for 1074 and 1707 strains, respectively. The compounds used in this study did not show any toxicity in the human dermal fibroblasts and 4T1 cells (viability higher than 90%). The in silico study of these compounds revealed that their antivirulence activity could be due to their interaction with the PqsR, PqsE, and LasR receptors.
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Affiliation(s)
- Neda Shakour
- Student Research Committee, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.,Department of Medicinal Chemistry, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Elaheh Taheri
- Laboratory of Phytopathology, Department of Crop Protection, Ferdowsi University of Mashhad, Mashhad, Iran
| | - Fatemeh Rajabian
- Department of Pharmacodynamics and Toxicology, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Saeed Tarighi
- Laboratory of Phytopathology, Department of Crop Protection, Ferdowsi University of Mashhad, Mashhad, Iran
| | - Vahid Soheili
- Department of Pharmaceutical Control, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Farzin Hadizadeh
- Department of Medicinal Chemistry, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran.,Biotechnology Research Center, Pharmaceutical Technology Institute, Mashhad University of Medical Sciences, Mashhad, Iran
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31
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Recipient Cell Factors Influence Interbacterial Competition Mediated by Two Distinct Burkholderia dolosa Contact-Dependent Growth Inhibition Systems. J Bacteriol 2022; 204:e0054121. [PMID: 36000834 PMCID: PMC9487645 DOI: 10.1128/jb.00541-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Contact-dependent growth inhibition (CDI) systems mediate interbacterial antagonism between Gram-negative bacteria by delivering the toxic portion of a large surface protein (termed BcpA in Burkholderia species) to the cytoplasm of neighboring bacteria. Translocation of the antibacterial polypeptide into recipient cells requires specific recipient outer and inner membrane proteins, but the identity of these factors outside several model organisms is unknown. To identify genes involved in CDI susceptibility in the Burkholderia cepacia complex member Burkholderia dolosa, a transposon mutagenesis selection approach was used to enrich for mutants resistant to BcpA-1 or BcpA-2. Subsequent analysis showed that candidate regulatory genes contributed modestly to recipient cell susceptibility to B. dolosa CDI. However, most candidate deletion mutants did not show the same phenotypes as the corresponding transposon mutants. Whole-genome resequencing revealed that these transposon mutants also contained unique mutations within a three gene locus (wabO, BDAG_01006, and BDAG_01005) encoding predicted lipopolysaccharide (LPS) biosynthesis enzymes. B. dolosa wabO, BDAG_01006, or BDAG_01005 mutants were resistant to CDI and produced LPS with altered core oligosaccharide and O-antigen. Although BcpA-1 and BcpA-2 are dissimilar and expected to utilize different outer membrane receptors, intoxication by both proteins was similarly impacted by LPS changes. Together, these findings suggest that alterations in cellular regulation may indirectly impact the efficiency of CDI-mediated competition and demonstrate that LPS is required for intoxication by two distinct B. dolosa BcpA proteins. IMPORTANCEContact-dependent growth inhibition (CDI) system proteins, produced by many Gram-negative bacteria, are narrow spectrum antimicrobials that inhibit the growth of closely related neighboring bacteria. Here, we use the opportunistic pathogen Burkholderia dolosa to identify genes required for intoxication by two distinct CDI system proteins. Our findings suggest that B. dolosa recipient cells targeted by CDI systems are only intoxicated if they produce full-length lipopolysaccharide. Understanding the mechanisms underlying antagonistic interbacterial interactions may contribute to future therapeutic development.
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Taylor IR, Jeffrey PD, Moustafa DA, Goldberg JB, Bassler BL. The PqsE Active Site as a Target for Small Molecule Antimicrobial Agents against Pseudomonas aeruginosa. Biochemistry 2022; 61:1894-1903. [PMID: 35985643 PMCID: PMC9454246 DOI: 10.1021/acs.biochem.2c00334] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
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The opportunistic pathogen Pseudomonas
aeruginosa causes antibiotic-resistant, nosocomial
infections in immuno-compromised
individuals and is a high priority for antimicrobial development.
Key to pathogenicity in P. aeruginosa are biofilm formation and virulence factor production. Both traits
are controlled by the cell-to-cell communication process called quorum
sensing (QS). QS involves the synthesis, release, and population-wide
detection of signal molecules called autoinducers. We previously reported
that the activity of the RhlR QS transcription factor depends on a
protein–protein interaction with the hydrolase, PqsE, and PqsE
catalytic activity is dispensable for this interaction. Nonetheless,
the PqsE–RhlR interaction could be disrupted by the substitution
of an active site glutamate residue with tryptophan [PqsE(E182W)].
Here, we show that disruption of the PqsE–RhlR interaction
via either the E182W change or alteration of PqsE surface residues
that are essential for the interaction with RhlR attenuates P. aeruginosa infection in a murine host. We use
crystallography to characterize the conformational changes induced
by the PqsE(E182W) substitution to define the mechanism underlying
disruption of the PqsE–RhlR interaction. A loop rearrangement
that repositions the E280 residue in PqsE(E182W) is responsible for
the loss of interaction. We verify the implications garnered from
the PqsE(E182W) structure using mutagenic, biochemical, and additional
structural analyses. We present the next generation of molecules targeting
the PqsE active site, including a structure of the tightest binding
of these compounds, BB584, in complex with PqsE. The findings presented
here provide insights into drug discovery against P.
aeruginosa with PqsE as the target.
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Affiliation(s)
- Isabelle R Taylor
- Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544, United States
| | - Philip D Jeffrey
- Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544, United States
| | - Dina A Moustafa
- School of Medicine, Children's Healthcare of Atlanta, Inc., Department of Pediatrics, and Center for Cystic Fibrosis and Airway Diseases Research, Emory University, Atlanta, Georgia 30322, United States
| | - Joanna B Goldberg
- School of Medicine, Children's Healthcare of Atlanta, Inc., Department of Pediatrics, and Center for Cystic Fibrosis and Airway Diseases Research, Emory University, Atlanta, Georgia 30322, United States
| | - Bonnie L Bassler
- Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544, United States.,Howard Hughes Medical Institute, Chevy Chase, Maryland 20815, United States
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RasI/R Quorum Sensing System Controls the Virulence of Ralstonia solanacearum Strain EP1. Appl Environ Microbiol 2022; 88:e0032522. [PMID: 35876567 PMCID: PMC9361817 DOI: 10.1128/aem.00325-22] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Quorum sensing (QS) is a widely conserved bacterial regulatory mechanism that relies on production and perception of autoinducing chemical signals to coordinate diverse cooperative activities, such as virulence, exoenzyme secretion, and biofilm formation. In Ralstonia solanacearum, a phytopathogen causing severe bacterial wilt diseases in many plant species, previous studies identified the PhcBSR QS system, which plays a key role in regulation of its physiology and virulence. In this study, we found that R. solanacearum strain EP1 contains the genes encoding uncharacterized LuxI/LuxR (LuxI/R) QS homologues (RasI/RasR [designated RasI/R here]). To determine the roles of the RasI/R system in strain EP1, we constructed a specific reporter for the signals catalyzed by RasI. Chromatography separation and structural analysis showed that RasI synthesized primarily N-(3-hydroxydodecanoyl)-homoserine lactone (3-OH-C12-HSL). In addition, we showed that the transcriptional expression of rasI is regulated by RasR in response to 3-OH-C12-HSL. Phenotype analysis unveiled that the RasI/R system plays a critical role in modulation of cellulase production, motility, biofilm formation, oxidative stress response, and virulence of R. solanacearum EP1. We then further characterized this system by determining the RasI/R regulon using transcriptome sequencing (RNA-seq) analysis, which showed that this newly identified QS system regulates the transcriptional expression of over 154 genes associated with bacterial physiology and pathogenic properties. Taken together, the findings from this study present an essential new QS system in regulation of R. solanacearum physiology and virulence and provide new insight into the complicated regulatory mechanisms and networks in this important plant pathogen. IMPORTANCE Quorum sensing (QS) is a key regulator of virulence factors in many plant-pathogenic bacteria. Previous studies unveiled two QS systems (i.e., PhcBSR and SolI/R) in several R. solanacearum strains. The PhcBSR QS system is known for its key roles in regulation of bacterial virulence, and the LuxI/LuxR (SolI/R) QS system appears dispensable for pathogenicity in a number of R. solanacearum strains. In this study, a new functional QS system (i.e., RasI/R) was identified and characterized in R. solanacearum strain EP1 isolated from infected eggplants. Phenotype analyses showed that the RasI/R system plays an important role in regulation of a range of biological activities associated with bacterial virulence. This QS system produces and responds to the QS signal 3-OH-C12-HSL and hence regulates critical bacterial abilities in survival and infection. To date, multiple QS signaling circuits in R. solanacearum strains are still not well understood. Our findings from this study provide new insight into the complicated QS regulatory networks that govern the physiology and virulence of R. solanacearum and present a valid target and clues for the control and prevention of bacterial wilt diseases.
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Choi HY, Le DD, Kim WG. Curvularin Isolated From Phoma macrostoma Is an Antagonist of RhlR Quorum Sensing in Pseudomonas aeruginosa. Front Microbiol 2022; 13:913882. [PMID: 35903467 PMCID: PMC9315252 DOI: 10.3389/fmicb.2022.913882] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 06/20/2022] [Indexed: 11/15/2022] Open
Abstract
Quorum sensing (QS) is an attractive target for the treatment of multidrug-resistant Pseudomonas aeruginosa, against which new antibiotics are urgently needed. Because LasR is at the top of the QS hierarchy controlling Rhl and PQS systems, most QS inhibitors have been targeted to LasR. However, it has recently been reported that in clinical isolates of P. aeruginosa, LasR is frequently mutated and nonfunctional, and RhlR independently acts to produce virulent factors that maintain toxicity. Thus, for effective treatment of chronic cystic fibrosis infections, RhlR antagonists is needed to prevent the LasR-independent Rhl system, but RhlR antagonists have rarely been reported. In this study, we found that curvularin, an aromatic compound with a cyclized alkyl side chain isolated from Phoma macrostoma, at a low micromolar concentration of 1–30 μM potently and selectively inhibited pyocyanin and rhamnolipid production without affecting the cell viability of P. aeruginosa. Only high concentration (more over 100 μM) curvularin negligibly inhibited biofilm formation and elastase production, suggesting that curvularin at low concentrations selectively inhibits RhlR. The QS antagonism by curvularin was investigated in experiments using QS competition and signaling molecules assays with QS gene expression analysis, and the results showed that, indeed, at low concentrations, curvularin selectively antagonized RhlR; in contrast, it negligibly antagonized LasR only when applied at a high concentration. The exclusive RhlR antagonizing activity of curvularin at low concentrations was confirmed using QS mutants; specifically, curvularin at low concentrations inhibited pyocyanin and rhamnolipid production by selectively antagonizing N-butanoyl homoserine lactone (BHL)-activated RhlR. Moreover, by targeting RhlR, curvularin reduced the in vivo virulence of wild-type P. aeruginosa as well as lasR mutants in Caenorhabditis elegans. Overall, low-concentration curvularin is a pure RhlR antagonist in P. aeruginosa, and to the best of our knowledge, this is the first report describing an RhlR antagonist from natural resources. Hence, curvularin has great potential for the development of chronic P. aeruginosa infection therapeutics and for the study of RhlR function in the complex QS system.
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Affiliation(s)
- Ha-Young Choi
- Infectious Disease Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, South Korea
- Department of Bio-Molecular Science, KRIBB School of Bioscience, Korea University of Science and Technology (UST), Daejeon, South Korea
| | - Duc Dat Le
- Infectious Disease Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, South Korea
| | - Won-Gon Kim
- Infectious Disease Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, South Korea
- Department of Bio-Molecular Science, KRIBB School of Bioscience, Korea University of Science and Technology (UST), Daejeon, South Korea
- *Correspondence: Won-Gon Kim,
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Didehdar M, Chegini Z, Tabaeian SP, Razavi S, Shariati A. Cinnamomum: The New Therapeutic Agents for Inhibition of Bacterial and Fungal Biofilm-Associated Infection. Front Cell Infect Microbiol 2022; 12:930624. [PMID: 35899044 PMCID: PMC9309250 DOI: 10.3389/fcimb.2022.930624] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 06/17/2022] [Indexed: 11/13/2022] Open
Abstract
Due to the potent antibacterial properties of Cinnamomum and its derivatives, particularly cinnamaldehyde, recent studies have used these compounds to inhibit the growth of the most prevalent bacterial and fungal biofilms. By inhibiting flagella protein synthesis and swarming motility, Cinnamomum could suppress bacterial attachment, colonization, and biofilm formation in an early stage. Furthermore, by downregulation of Cyclic di‐guanosine monophosphate (c‐di‐GMP), biofilm-related genes, and quorum sensing, this compound suppresses intercellular adherence and accumulation of bacterial cells in biofilm and inhibits important bacterial virulence factors. In addition, Cinnamomum could lead to preformed biofilm elimination by enhancing membrane permeability and the disruption of membrane integrity. Moreover, this substance suppresses the Candida species adherence to the oral epithelial cells, leading to the cell wall deformities, damage, and leakages of intracellular material that may contribute to the established Candida’s biofilm elimination. Therefore, by inhibiting biofilm maturation and destroying the external structure of biofilm, Cinnamomum could boost antibiotic treatment success in combination therapy. However, Cinnamomum has several disadvantages, such as poor solubility in aqueous solution, instability, and volatility; thus, the use of different drug-delivery systems may resolve these limitations and should be further considered in future investigations. Overall, Cinnamomum could be a promising agent for inhibiting microbial biofilm-associated infection and could be used as a catheter and other medical materials surface coatings to suppress biofilm formation. Nonetheless, further in vitro toxicology analysis and animal experiments are required to confirm the reported molecular antibiofilm effect of Cinnamomum and its derivative components against microbial biofilm.
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Affiliation(s)
- Mojtaba Didehdar
- Department of Medical Parasitology and Mycology, Arak University of Medical Sciences, Arak, Iran
| | - Zahra Chegini
- Department of Microbiology, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Seidamir Pasha Tabaeian
- Department of Internal Medicine, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
- Colorectal Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Shabnam Razavi
- Microbial Biotechnology Research Center, Iran University of Medical Sciences, Tehran, Iran
- Department of Microbiology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Aref Shariati
- Molecular and Medicine Research Center, Khomein University of Medical Sciences, Khomein, Iran
- *Correspondence: Aref Shariati,
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36
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Letizia M, Mellini M, Fortuna A, Visca P, Imperi F, Leoni L, Rampioni G. PqsE Expands and Differentially Modulates the RhlR Quorum Sensing Regulon in Pseudomonas aeruginosa. Microbiol Spectr 2022; 10:e0096122. [PMID: 35604161 PMCID: PMC9241726 DOI: 10.1128/spectrum.00961-22] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Accepted: 05/02/2022] [Indexed: 12/22/2022] Open
Abstract
In the opportunistic pathogen Pseudomonas aeruginosa, many virulence traits are finely regulated by quorum sensing (QS), an intercellular communication system that allows the cells of a population to coordinate gene expression in response to cell density. The key aspects underlying the functionality of the complex regulatory network governing QS in P. aeruginosa are still poorly understood, including the interplay between the effector protein PqsE and the transcriptional regulator RhlR in controlling the QS regulon. Different studies have focused on the characterization of PqsE- and RhlR-controlled genes in genetic backgrounds in which RhlR activity can be modulated by PqsE and pqsE expression is controlled by RhlR, thus hampering identification of the distinct regulons controlled by PqsE and RhlR. In this study, a P. aeruginosa PAO1 mutant strain with deletion of multiple QS elements and inducible expression of pqsE and/or rhlR was generated and validated. Transcriptomic analyses performed on this genetic background allowed us to unambiguously define the regulons controlled by PqsE and RhlR when produced alone or in combination. Transcriptomic data were validated via reverse transcription-quantitative PCR (RT-qPCR) and transcriptional fusions. Overall, our results showed that PqsE has a negligible effect on the P. aeruginosa transcriptome in the absence of RhlR, and that multiple RhlR subregulons exist with distinct dependency on PqsE. Overall, this study contributes to untangling the regulatory link between the pqs and rhl QS systems mediated by PqsE and RhlR and clarifying the impact of these QS elements on the P. aeruginosa transcriptome. IMPORTANCE The ability of Pseudomonas aeruginosa to cause difficult-to-treat infections relies on its capacity to fine-tune the expression of multiple virulence traits via the las, rhl, and pqs QS systems. Both the pqs effector protein PqsE and the rhl transcriptional regulator RhlR are required for full production of key virulence factors in vitro and pathogenicity in vivo. While it is known that PqsE can stimulate the ability of RhlR to control some virulence factors, no data are available to allow clear discrimination of the PqsE and RhlR regulons. The data produced in this study demonstrate that PqsE mainly impacts the P. aeruginosa transcriptome via an RhlR-dependent pathway and splits the RhlR regulon into PqsE-dependent and PqsE-independent subregulons. Besides contributing to untangling of the complex QS network of P. aeruginosa, our data confirm that both PqsE and RhlR are suitable targets for the development of antivirulence drugs.
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Affiliation(s)
| | - Marta Mellini
- Department of Science, Roma Tre University, Rome, Italy
| | | | - Paolo Visca
- Department of Science, Roma Tre University, Rome, Italy
- IRCCS Fondazione Santa Lucia, Rome, Italy
| | - Francesco Imperi
- Department of Science, Roma Tre University, Rome, Italy
- IRCCS Fondazione Santa Lucia, Rome, Italy
| | - Livia Leoni
- Department of Science, Roma Tre University, Rome, Italy
| | - Giordano Rampioni
- Department of Science, Roma Tre University, Rome, Italy
- IRCCS Fondazione Santa Lucia, Rome, Italy
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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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Targeting the Holy Triangle of Quorum Sensing, Biofilm Formation, and Antibiotic Resistance in Pathogenic Bacteria. Microorganisms 2022; 10:microorganisms10061239. [PMID: 35744757 PMCID: PMC9228545 DOI: 10.3390/microorganisms10061239] [Citation(s) in RCA: 43] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Revised: 06/12/2022] [Accepted: 06/14/2022] [Indexed: 12/12/2022] Open
Abstract
Chronic and recurrent bacterial infections are frequently associated with the formation of biofilms on biotic or abiotic materials that are composed of mono- or multi-species cultures of bacteria/fungi embedded in an extracellular matrix produced by the microorganisms. Biofilm formation is, among others, regulated by quorum sensing (QS) which is an interbacterial communication system usually composed of two-component systems (TCSs) of secreted autoinducer compounds that activate signal transduction pathways through interaction with their respective receptors. Embedded in the biofilms, the bacteria are protected from environmental stress stimuli, and they often show reduced responses to antibiotics, making it difficult to eradicate the bacterial infection. Besides reduced penetration of antibiotics through the intricate structure of the biofilms, the sessile biofilm-embedded bacteria show reduced metabolic activity making them intrinsically less sensitive to antibiotics. Moreover, they frequently express elevated levels of efflux pumps that extrude antibiotics, thereby reducing their intracellular levels. Some efflux pumps are involved in the secretion of QS compounds and biofilm-related materials, besides being important for removing toxic substances from the bacteria. Some efflux pump inhibitors (EPIs) have been shown to both prevent biofilm formation and sensitize the bacteria to antibiotics, suggesting a relationship between these processes. Additionally, QS inhibitors or quenchers may affect antibiotic susceptibility. Thus, targeting elements that regulate QS and biofilm formation might be a promising approach to combat antibiotic-resistant biofilm-related bacterial infections.
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The human "contaminome": bacterial, viral, and computational contamination in whole genome sequences from 1000 families. Sci Rep 2022; 12:9863. [PMID: 35701436 PMCID: PMC9198055 DOI: 10.1038/s41598-022-13269-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 05/18/2022] [Indexed: 01/11/2023] Open
Abstract
The unmapped readspace of whole genome sequencing data tends to be large but is often ignored. We posit that it contains valuable signals of both human infection and contamination. Using unmapped and poorly aligned reads from whole genome sequences (WGS) of over 1000 families and nearly 5000 individuals, we present insights into common viral, bacterial, and computational contamination that plague whole genome sequencing studies. We present several notable results: (1) In addition to known contaminants such as Epstein-Barr virus and phiX, sequences from whole blood and lymphocyte cell lines contain many other contaminants, likely originating from storage, prep, and sequencing pipelines. (2) Sequencing plate and biological sample source of a sample strongly influence contamination profile. And, (3) Y-chromosome fragments not on the human reference genome commonly mismap to bacterial reference genomes. Both experiment-derived and computational contamination is prominent in next-generation sequencing data. Such contamination can compromise results from WGS as well as metagenomics studies, and standard protocols for identifying and removing contamination should be developed to ensure the fidelity of sequencing-based studies.
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40
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Huang XH, She MT, Zhang YH, Liu YF, Zhong DX, Zhang YH, Zheng JX, Sun N, Wong WL, Lu YJ. Novel quinoline-based derivatives as the PqsR inhibitor against Pseudomonas aeruginosa PAO1. J Appl Microbiol 2022; 133:2167-2181. [PMID: 35490292 DOI: 10.1111/jam.15601] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 04/19/2022] [Accepted: 04/26/2022] [Indexed: 11/27/2022]
Abstract
AIMS The emerging of drug resistant Pseudomonas aeruginosa is a critical challenge and renders an urgent action to discover innovative antimicrobial interventions. One of these interventions is to disrupt the pseudomonas quinolone signal (pqs) quorum sensing (QS) system, which governs multiple virulence traits and biofilm formation. This study aimed to investigate the QS inhibitory activity of a series of new PqsR inhibitors bearing a quinoline scaffold against Ps. aeruginosa. METHODS AND RESULTS The results showed that compound 1 suppressed the expression of QS-related genes and showed the best inhibitory activity to the pqs system of wild-type Ps. aeruginosa PAO1 with an IC50 of 20.22 μmol l-1 . The virulence factors including pyocyanin, total protease, elastase, and rhamnolipid were significantly suppressed in a concentration-dependent manner with the compound. In addition, 1 in combination with tetracycline inhibited synergistically the bacterial growth and suppressed the biofilm formation of PAO1. The molecular docking studies also suggested that 1 could potentially interact with the ligand-binding domain of the Lys-R type transcriptional regulator PqsR as a competitive antagonist. CONCLUSIONS The quinoline-based derivatives were found to interrupt the quorum sensing system via the pqs pathway and thus the production of virulence factors was inhibited and the antimicrobial susceptibility of Ps. aeruginosa was enhanced. SIGNIFICANCE AND IMPACT OF STUDY The study showed that the quinoline-based derivatives could be used as an anti-virulence agent for treating Ps. aeruginosa infections.
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Affiliation(s)
- Xuan-He Huang
- School of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou, P. R. China
| | - Meng-Ting She
- School of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou, P. R. China
| | - Yi-Hang Zhang
- School of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou, P. R. China
| | - Yi-Fu Liu
- School of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou, P. R. China
| | - Dong-Xiao Zhong
- School of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou, P. R. China
| | - Yi-Han Zhang
- School of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou, P. R. China
| | - Jun-Xia Zheng
- School of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou, P. R. China
| | - Ning Sun
- State Key Laboratory of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong, SAR, China.,Guangzhou First People's Hospital, School of Medicine, South China University of Technology, Guangzhou, P. R. China
| | - Wing-Leung Wong
- State Key Laboratory of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong, SAR, China
| | - Yu-Jing Lu
- School of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou, P. R. China.,Engineering Research Academy of High Value Utilization of Green Plants, Meizhou, P. R. China.,Golden Health (Guangdong) Biotechnology Co., Ltd, Foshan, P. R. China
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Genetic and Transcriptomic Characteristics of RhlR-Dependent Quorum Sensing in Cystic Fibrosis Isolates of Pseudomonas aeruginosa. mSystems 2022; 7:e0011322. [PMID: 35471121 PMCID: PMC9040856 DOI: 10.1128/msystems.00113-22] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
In people with the genetic disease cystic fibrosis (CF), bacterial infections involving the opportunistic pathogen Pseudomonas aeruginosa are a significant cause of morbidity and mortality. P. aeruginosa uses a cell-cell signaling mechanism called quorum sensing (QS) to regulate many virulence functions. One type of QS consists of acyl-homoserine lactone (AHL) signals produced by LuxI-type signal synthases, which bind a cognate LuxR-type transcription factor. In laboratory strains and conditions, P. aeruginosa employs two AHL synthase/receptor pairs arranged in a hierarchy, with the LasI/R system controlling the RhlI/R system and many downstream virulence factors. However, P. aeruginosa isolates with inactivating mutations in lasR are frequently isolated from chronic CF infections. We and others have shown that these isolates frequently use RhlR as the primary QS regulator. RhlR is rarely mutated in CF and environmental settings. We were interested in determining whether there were reproducible genetic characteristics of these isolates and whether there was a central group of genes regulated by RhlR in all isolates. We examined five isolates and found signatures of adaptation common to CF isolates. We did not identify a common genetic mechanism to explain the switch from Las- to Rhl-dominated QS. We describe a core RhlR regulon encompassing 20 genes encoding 7 products. These results suggest a key group of QS-regulated factors important for pathogenesis of chronic infections and position RhlR as a target for anti-QS therapeutics. Our work underscores the need to sample a diversity of isolates to understand QS beyond what has been described in laboratory strains. IMPORTANCE The bacterial pathogen Pseudomonas aeruginosa can cause chronic infections that are resistant to treatment in immunocompromised individuals. Over the course of these infections, the original infecting organism adapts to the host environment. P. aeruginosa uses a cell-cell signaling mechanism termed quorum sensing (QS) to regulate virulence factors and cooperative behaviors. The key QS regulator in laboratory strains, LasR, is frequently mutated in infection-adapted isolates, leaving another transcription factor, RhlR, in control of QS gene regulation. Such isolates provide an opportunity to understand Rhl-QS regulation without the confounding effects of LasR, as well as the scope of QS in the context of within-host evolution. We show that a core group of virulence genes is regulated by RhlR in a variety of infection-adapted LasR-null isolates. Our results reveal commonalities in infection-adapted QS gene regulation and key QS factors that may serve as therapeutic targets in the future.
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Phage Infection Restores PQS Signaling and Enhances Growth of a Pseudomonas aeruginosa lasI Quorum-Sensing Mutant. J Bacteriol 2022; 204:e0055721. [PMID: 35389255 PMCID: PMC9112912 DOI: 10.1128/jb.00557-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Chemical communication between bacteria and between bacteria and the bacteriophage (phage) viruses that prey on them can shape the outcomes of phage-bacterial encounters. Quorum sensing (QS) is a bacterial cell-to-cell communication process that promotes collective undertaking of group behaviors. QS relies on the production, release, accumulation, and detection of signal molecules called autoinducers. Phages can exploit QS-mediated communication to manipulate their hosts and maximize their own survival. In the opportunistic pathogen Pseudomonas aeruginosa, the LasI/R QS system induces the RhlI/R QS system, and in opposing manners, these two systems control the QS system that relies on the autoinducer called PQS. A P. aeruginosa ΔlasI mutant is impaired in PQS synthesis, leading to accumulation of the precursor molecule HHQ, and HHQ suppresses growth of the P. aeruginosa ΔlasI strain. We show that, in response to a phage infection, the P. aeruginosa ΔlasI mutant reactivates QS, which, in turn, restores pqsH expression, enabling conversion of HHQ into PQS. Moreover, downstream QS target genes encoding virulence factors are induced. Additionally, phage-infected P. aeruginosa ΔlasI cells transiently exhibit superior growth compared to uninfected cells. IMPORTANCE Clinical isolates of P. aeruginosa frequently harbor mutations in particular QS genes. Here, we show that infection by select temperate phages restores QS, a cell-to-cell communication mechanism in a P. aeruginosa QS mutant. Restoration of QS increases expression of genes encoding virulence factors. Thus, phage infection of select P. aeruginosa strains may increase bacterial pathogenicity, underscoring the importance of characterizing phage-host interactions in the context of bacterial mutants that are relevant in clinical settings.
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ABCDs of the Relative Contributions of Pseudomonas aeruginosa Quorum Sensing Systems to Virulence in Diverse Nonvertebrate Hosts. mBio 2022; 13:e0041722. [PMID: 35311532 PMCID: PMC9040828 DOI: 10.1128/mbio.00417-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Pseudomonas aeruginosa is an opportunistic bacterial pathogen that exhibits pathogenicity in an unusually broad range of plants and animals, and it is of interest to study the roles of particular virulence-related factors in diverse hosts. The production of many P. aeruginosa virulence factors is under the control of a quorum sensing (QS) signaling network, which has three interconnected branches that engage in intricate cross talk: Las, Rhl, and MvfR. Because there has been no systematic comparison of the roles of the three QS systems in mediating P. aeruginosa virulence in various hosts, we compared the virulence of wild-type (WT) P. aeruginosa PA14 and a set of isogenic PA14 QS in-frame deletion mutants in four selected hosts, the reference plant Arabidopsis thaliana (Arabidopsis), the crop plant Brassica napus (canola), the nematode Caenorhabditis elegans, and the fruit fly Drosophila melanogaster. The first letters of the selected host genera, A, B, C, and D, inspired the title of this article and indicate that this work lays the groundwork for future elucidation of the specific roles of each QS branch in mediating virulence in diverse hosts.
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Abstract
Pseudomonas aeruginosa is an opportunistic and nosocomial pathogen of humans with hundreds of its virulence factors regulated by quorum sensing (QS) system. Small noncoding RNAs (sRNAs) are also key regulators of bacterial virulence. However, the QS regulatory sRNAs (Qrrs) that have been characterized in P. aeruginosa are still largely unknown. Here, sRNA AmiL (PA3366.1) in the amiEBCRS operon of PAO1 was identified as a novel Qrr by transcriptome sequencing (RNA-Seq). The expression of AmiL was negatively regulated by the las or rhl system, of which RhlR probably inhibited its transcription. AmiL deletion mutant and overexpressing strains were constructed in PAO1. Broad phenotypic changes were found, including reduced pyocyanin synthesis, elastase activity, biofilm formation, hemolytic activity, and cytotoxicity, as well as increased rhamnolipid production and swarming motility. AmiL appears to be a new regulator that influences diverse QS-mediated virulence. Furthermore, AmiL directly targeted PhzC, a key member of pyocyanin synthesis. AmiL also negatively regulated lasI expression in the early growth of PAO1, but predominantly increased rhlI expression and C4-HSL production in the middle and late stages. Therefore, a novel QS-sRNA signaling cascade of las/rhl (RhlR)-AmiL-PhzC/las/rhl was demonstrated, and it will help to shed new light on the virulence regulatory network of P. aeruginosa PAO1. IMPORTANCEP. aeruginosa is a common nosocomial pathogen that causes diverse opportunistic infections in humans. The virulence crucial for infection is mainly regulated by QS. Small noncoding RNAs (sRNAs) involved in virulence regulation have also been identified in many bacteria. Recently, there is a growing interest in the new sRNA species, QS regulatory sRNAs (Qrrs). Understanding Qrrs-mediated regulation in P. aeruginosa virulence is therefore important to combat infection. In this study, a previously uncharacterized sRNA AmiL in PAO1 has been identified as a novel Qrr. It has been found to influence diverse QS-mediated virulence factors including pyocyanin, elastase, rhamnolipid, and hemolysin, as well as biofilm formation, swarming motility, and cytotoxicity. Furthermore, PhzC essential for pyocyanin synthesis was a direct target of AmiL. QS gene expression and C4-HSL production were also regulated by AmiL. This study provides insights into the roles of Qrr AmiL in modulating P. aeruginosa virulence.
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LuxT Is a Global Regulator of Low-Cell-Density Behaviors, Including Type III Secretion, Siderophore Production, and Aerolysin Production, in Vibrio harveyi. mBio 2022; 13:e0362121. [PMID: 35038896 PMCID: PMC8764538 DOI: 10.1128/mbio.03621-21] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Quorum sensing (QS) is a chemical communication process in which bacteria produce, release, and detect extracellular signaling molecules called autoinducers. Via combined transcriptional and posttranscriptional regulatory mechanisms, QS allows bacteria to collectively alter gene expression on a population-wide scale. Recently, the TetR family transcriptional regulator LuxT was shown to control Vibrio harveyi qrr1, encoding the Qrr1 small RNA that functions at the core of the QS regulatory cascade. Here, we use RNA sequencing to reveal that, beyond the control of qrr1, LuxT is a global regulator of 414 V. harveyi genes, including those involved in type III secretion, siderophore production, and aerolysin toxin biosynthesis. Importantly, LuxT directly represses swrZ, encoding a GntR family transcriptional regulator, and LuxT control of type III secretion, siderophore, and aerolysin genes occurs by two mechanisms, one that is SwrZ dependent and one that is SwrZ independent. All of these target genes specify QS-controlled behaviors that are enacted when V. harveyi is at low cell density. Thus, LuxT and SwrZ function in parallel with QS to drive particular low-cell-density behaviors. Phylogenetic analyses reveal that luxT is highly conserved among Vibrionaceae, but swrZ is less well conserved. In a test case, we find that in Aliivibrio fischeri, LuxT also represses swrZ. SwrZ is a repressor of A. fischeri siderophore production genes. Thus, LuxT repression of swrZ drives the activation of A. fischeri siderophore gene expression. Our results indicate that LuxT is a major regulator among Vibrionaceae, and in the species that also possess swrZ, LuxT functions with SwrZ to control gene expression. IMPORTANCE Bacteria precisely tune gene expression patterns to successfully react to changes that occur in the environment. Defining the mechanisms that enable bacteria to thrive in diverse and fluctuating habitats, including in host organisms, is crucial for a deep understanding of the microbial world and also for the development of effective applications to promote or combat particular bacteria. In this study, we show that a regulator called LuxT controls over 400 genes in the marine bacterium Vibrio harveyi and that LuxT is highly conserved among Vibrionaceae species, ubiquitous marine bacteria that often cause disease. We characterize the mechanisms by which LuxT controls genes involved in virulence and nutrient acquisition. We show that LuxT functions in parallel with a set of regulators of the bacterial cell-to-cell communication process called quorum sensing to promote V. harveyi behaviors at low cell density.
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Recent Advance in Small Molecules Targeting RhlR of Pseudomonas aeruginosa. Antibiotics (Basel) 2022; 11:antibiotics11020274. [PMID: 35203876 PMCID: PMC8868144 DOI: 10.3390/antibiotics11020274] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 02/17/2022] [Accepted: 02/18/2022] [Indexed: 12/02/2022] Open
Abstract
Pseudomonas aeruginosa (P. aeruginosa) is an opportunistic gram-negative pathogen that can cause various infections, particularly in patients with compromised host defenses. P. aeruginosa forms biofilms and produces virulence factors through quorum sensing (QS) network, resulting in resistance to antibiotics. RhlI/RhlR, one of key QS systems in P. aeruginosa, is considered an attractive target for inhibiting biofilm formation and attenuating virulence factors. Several recent studies examined small molecules targeting the RhlI/RhlR system and their in vitro and in vivo biological activities. In this review, RhlR-targeted modulators, including agonists and antagonists, are discussed with particular focus on structure-activity relationship studies and outlook for next-generation anti-biofilm agents.
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Anthranilate Acts as a Signal to Modulate Biofilm Formation, Virulence, and Antibiotic Tolerance of Pseudomonas aeruginosa and Surrounding Bacteria. Microbiol Spectr 2022; 10:e0146321. [PMID: 35019684 PMCID: PMC8754147 DOI: 10.1128/spectrum.01463-21] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Anthranilate is a diffusible molecule produced by Pseudomonas aeruginosa and accumulates as P. aeruginosa grows. Anthranilate is an important intermediate for the synthesis of tryptophan and the Pseudomonas quinolone signal (PQS), as well as metabolized by the anthranilate dioxygenase complex (antABC operon products). Here we demonstrate that anthranilate is a key factor that modulates the pathogenicity-related phenotypes of P. aeruginosa and other surrounding bacteria in the environment, such as biofilm formation, antibiotic tolerance, and virulence. We found that the anthranilate levels in P. aeruginosa cultures rapidly increased in the stationary phase and then decreased again, forming an anthranilate peak. Biofilm formation, antibiotic susceptibility, and virulence of P. aeruginosa were significantly altered before and after this anthranilate peak. In addition, these phenotypes were all modified by the mutation of antABC and exogenous addition of anthranilate. Anthranilate also increased the antibiotic susceptibility of other species of bacteria, such as Escherichia coli, Salmonella enterica, Bacillus subtilis, and Staphylococcus aureus. Before the anthranilate peak, the low intracellular anthranilate level was maintained through degradation from the antABC function, in which induction of antABC was also limited to a small extent. The premature degradation of anthranilate, due to its high levels, and antABC expression early in the growth phase, appears to be toxic to the cells. From these results, we propose that by generating an anthranilate peak as a signal, P. aeruginosa may induce some sort of physiological change in surrounding cells. IMPORTANCE Pseudomonas aeruginosa is a notorious pathogen with high antibiotic resistance, strong virulence, and ability to cause biofilm-mediated chronic infection. We found that these characteristics change profoundly before and after the time when anthranilate is produced as an "anthranilate peak". This peak acts as a signal that induces physiological changes in surrounding cells, decreasing their antibiotic tolerance and biofilm formation. This study is important in that it provides a new insight into how microbial signaling substances can induce changes in the pathogenicity-related phenotypes of cells in the environment. In addition, this study shows that anthranilate can be used as an adjuvant to antibiotics.
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Transcriptome analysis of Pseudomonas aeruginosa biofilm infection in an ex vivo pig model of the cystic fibrosis lung. Appl Environ Microbiol 2021; 88:e0178921. [PMID: 34878811 PMCID: PMC8824274 DOI: 10.1128/aem.01789-21] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Pseudomonas aeruginosa is the predominant cause of chronic biofilm infections that form in the lungs of people with cystic fibrosis (CF). These infections are highly resistant to antibiotics and persist for years in the respiratory tract. One of the main research challenges is that current laboratory models do not accurately replicate key aspects of a P. aeruginosa biofilm infection, highlighted by previous RNA-sequencing studies. We compared the P. aeruginosa PA14 transcriptome in an ex vivo pig lung (EVPL) model of CF and a well-studied synthetic cystic fibrosis sputum medium (SCFM). P. aeruginosa was grown in the EVPL model for 1, 2, and 7 days, and in vitro in SCFM for 1 and 2 days. The RNA was extracted and sequenced at each time point. Our findings demonstrate that expression of antimicrobial resistance genes was cued by growth in the EVPL model, highlighting the importance of growth environment in determining accurate resistance profiles. The EVPL model created two distinct growth environments: tissue-associated biofilm and the SCFM surrounding tissue, each cuing a transcriptome distinct from that seen in SCFM in vitro. The expression of quorum sensing associated genes in the EVPL tissue-associated biofilm at 48 h relative to in vitro SCFM was similar to CF sputum versus in vitro conditions. Hence, the EVPL model can replicate key aspects of in vivo biofilm infection that are missing from other current models. It provides a more accurate P. aeruginosa growth environment for determining antimicrobial resistance that quickly drives P. aeruginosa into a chronic-like infection phenotype. IMPORTANCEPseudomonas aeruginosa lung infections that affect people with cystic fibrosis are resistant to most available antimicrobial treatments. The lack of a laboratory model that captures all key aspects of these infections hinders not only research progression but also clinical diagnostics. We used transcriptome analysis to demonstrate how a model using pig lungs can more accurately replicate key characteristics of P. aeruginosa lung infection, including mechanisms of antibiotic resistance and infection establishment. Therefore, this model may be used in the future to further understand infection dynamics to develop novel treatments and more accurate treatment plans. This could improve clinical outcomes as well as quality of life for individuals affected by these infections.
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Duplantier M, Lohou E, Sonnet P. Quorum Sensing Inhibitors to Quench P. aeruginosa Pathogenicity. Pharmaceuticals (Basel) 2021; 14:1262. [PMID: 34959667 PMCID: PMC8707152 DOI: 10.3390/ph14121262] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 12/01/2021] [Accepted: 12/02/2021] [Indexed: 12/22/2022] Open
Abstract
The emergence and the dissemination of multidrug-resistant bacteria constitute a major public health issue. Among incriminated Gram-negative bacteria, Pseudomonas aeruginosa has been designated by the WHO as a critical priority threat. During the infection process, this pathogen secretes various virulence factors in order to adhere and colonize host tissues. Furthermore, P. aeruginosa has the capacity to establish biofilms that reinforce its virulence and intrinsic drug resistance. The regulation of biofilm and virulence factor production of this micro-organism is controlled by a specific bacterial communication system named Quorum Sensing (QS). The development of anti-virulence agents targeting QS that could attenuate P. aeruginosa pathogenicity without affecting its growth seems to be a promising new therapeutic strategy. This could prevent the selective pressure put on bacteria by the conventional antibiotics that cause their death and promote resistant strain survival. This review describes the QS-controlled pathogenicity of P. aeruginosa and its different specific QS molecular pathways, as well as the recent advances in the development of innovative QS-quenching anti-virulence agents to fight anti-bioresistance.
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Affiliation(s)
| | | | - Pascal Sonnet
- AGIR, UR4294, UFR of Pharmacy, Jules Verne University of Picardie, 80037 Amiens, France; (M.D.); (E.L.)
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Sindeldecker D, Stoodley P. The many antibiotic resistance and tolerance strategies of Pseudomonas aeruginosa. Biofilm 2021; 3:100056. [PMID: 34471871 PMCID: PMC8387898 DOI: 10.1016/j.bioflm.2021.100056] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 08/17/2021] [Accepted: 08/18/2021] [Indexed: 12/15/2022] Open
Abstract
Pseudomonas aeruginosa is a bacterial pathogen associated with a wide range of infections and utilizes several strategies to establish and maintain infection including biofilm production, multidrug resistance, and antibiotic tolerance. Multidrug resistance in P. aeruginosa, as well as in all other bacterial pathogens, is a growing concern. Aminoglycoside resistance, in particular, is a major concern in P. aeruginosa infections and must be better understood in order to maintain effective clinical treatment. In this review, the various antibiotic resistance and tolerance mechanisms of Pseudomonas are explored including: classic mutation driven resistance, adaptive resistance, persister cells, small colony variants, phoenix colonies, and biofilms. It is important to further characterize each of these phenotypes and continue to evaluate antibiotic surviving isolates for novel driving mechanisms, so that we are better prepared to combat the rising number of recurrent and recalcitrant infections.
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Affiliation(s)
- Devin Sindeldecker
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH, USA
- Biomedical Sciences Graduate Program, The Ohio State University, Columbus, OH, USA
| | - Paul Stoodley
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH, USA
- Department of Orthopaedics, The Ohio State University, Columbus, OH, USA
- National Center for Advanced Tribology at Southampton (nCATS), Mechanical Engineering, University of Southampton, Southampton, UK
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