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Shahzad S, Krug SA, Mouriño S, Huang W, Kane MA, Wilks A. Pseudomonas aeruginosa heme metabolites biliverdin IXβ and IXδ are integral to lifestyle adaptations associated with chronic infection. mBio 2024; 15:e0276323. [PMID: 38319089 PMCID: PMC10936436 DOI: 10.1128/mbio.02763-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Accepted: 12/11/2023] [Indexed: 02/07/2024] Open
Abstract
Pseudomonas aeruginosa is a versatile opportunistic pathogen requiring iron for its survival and virulence within the host. The ability to switch to heme as an iron source and away from siderophore uptake provides an advantage in chronic infection. We have recently shown the extracellular heme metabolites biliverdin IXβ (BVIXβ) and BVIXδ positively regulate the heme-dependent cell surface signaling cascade. We further investigated the role of BVIXβ and BVIXδ in cell signaling utilizing allelic strains lacking a functional heme oxygenase (hemOin) or one reengineered to produce BVIXα (hemOα). Compared to PAO1, both strains show a heme-dependent growth defect, decreased swarming and twitching, and less robust biofilm formation. Interestingly, the motility and biofilm defects were partially rescued on addition of exogenous BVIXβ and BVIXδ. Utilizing liquid chromatography-tandem mass spectrometry, we performed a comparative proteomics and metabolomics analysis of PAO1 versus the allelic strains in shaking and static conditions. In shaking conditions, the hemO allelic strains showed a significant increase in proteins involved in quorum sensing, phenazine production, and chemotaxis. Metabolite profiling further revealed increased levels of Pseudomonas quinolone signal and phenazine metabolites. In static conditions, we observed a significant repression of chemosensory pathways and type IV pili biogenesis proteins as well as several phosphodiesterases associated with biofilm dispersal. We propose BVIX metabolites function as signaling and chemotactic molecules integrating heme utilization as an iron source into the adaptation of P. aeruginosa from a planktonic to sessile lifestyle. IMPORTANCE The opportunistic pathogen Pseudomonas aeruginosa causes long-term chronic infection in the airways of cystic fibrosis patients. The ability to scavenge iron and to establish chronic infection within this environment coincides with a switch to utilize heme as the primary iron source. Herein, we show the heme metabolites biliverdin beta and delta are themselves important signaling molecules integrating the switch in iron acquisition systems with cooperative behaviors such as motility and biofilm formation that are essential for long-term chronic infection. These significant findings will enhance the development of viable multi-targeted therapeutics effective against both heme utilization and cooperative behaviors essential for survival and persistence within the host.
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Affiliation(s)
- Saba Shahzad
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, Maryland, USA
| | - Samuel A. Krug
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, Maryland, USA
| | - Susana Mouriño
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, Maryland, USA
| | - Weiliang Huang
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, Maryland, USA
| | - Maureen A. Kane
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, Maryland, USA
| | - Angela Wilks
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, Maryland, USA
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2
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Pardue EJ, Sartorio MG, Jana B, Scott NE, Beatty WL, Ortiz-Marquez JC, Van Opijnen T, Hsu FF, Potter RF, Feldman MF. Dual membrane-spanning anti-sigma factors regulate vesiculation in Bacteroides thetaiotaomicron. Proc Natl Acad Sci U S A 2024; 121:e2321910121. [PMID: 38422018 DOI: 10.1073/pnas.2321910121] [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: 12/18/2023] [Accepted: 01/19/2024] [Indexed: 03/02/2024] Open
Abstract
Bacteroidota are abundant members of the human gut microbiota that shape the enteric landscape by modulating host immunity and degrading dietary- and host-derived glycans. These processes are mediated in part by Outer Membrane Vesicles (OMVs). Here, we developed a high-throughput screen to identify genes required for OMV biogenesis and its regulation in Bacteroides thetaiotaomicron (Bt). We identified a family of Dual membrane-spanning anti-sigma factors (Dma) that control OMV biogenesis. We conducted molecular and multiomic analyses to demonstrate that deletion of Dma1, the founding member of the Dma family, modulates OMV production by controlling the activity of the ECF21 family sigma factor, Das1, and its downstream regulon. Dma1 has a previously uncharacterized domain organization that enables Dma1 to span both the inner and outer membrane of Bt. Phylogenetic analyses reveal that this common feature of the Dma family is restricted to the phylum Bacteroidota. This study provides mechanistic insights into the regulation of OMV biogenesis in human gut bacteria.
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Affiliation(s)
- Evan J Pardue
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, MO 63110
| | - Mariana G Sartorio
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, MO 63110
| | - Biswanath Jana
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, MO 63110
| | - Nichollas E Scott
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville, VIC 3000, Australia
| | - Wandy L Beatty
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, MO 63110
| | | | | | - Fong-Fu Hsu
- Division of Endocrinology, Metabolism and Lipid Research, Washington University School of Medicine, Saint Louis, MO 63110
| | - Robert F Potter
- Department of Pediatrics, Washington University School of Medicine, Saint Louis, MO 63110
| | - Mario F Feldman
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, MO 63110
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3
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Li X, Yi S, Chen L, Hafeez M, Zhang Z, Zhang J, Zhou S, Dong W, Huang J, Lu Y. The application of entomopathogenic nematode modified microbial communities within nesting mounds of the red imported fire ants, Solenopsis invicta. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 912:168748. [PMID: 38008315 DOI: 10.1016/j.scitotenv.2023.168748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 11/10/2023] [Accepted: 11/19/2023] [Indexed: 11/28/2023]
Abstract
Entomopathogenic microorganisms (e.g., fungi, bacteria, nematodes) have been widely used in biological control of soil-dwelling pests, including the red imported fire ant (RIFA), Solenopsis invicta, a notorious invasive pest worldwide. The application of large amounts of entomopathogenic microorganisms to soil may affect the indigenous soil microbial communities. However, reports about the effect of entomopathogenic nematodes (EPN) on soil microbial communities are very few. In this study, the effects of EPN on RIFA populations and microbial communities in mounds were investigated. Our results showed that the application of the EPN Steinernema carpocapsae. All strain on mounds efficaciously suppressed RIFA worker populations, without forming significantly more satellite mounds compared with the control treatment. The application of EPN did not impact the bacterial and fungal diversity in soils derived from the RIFA mounds. However, it slightly altered the taxonomic make-up of the bacterial communities, but significantly altered the taxonomic composition of fungal communities at the phylum, family, and genus levels. The abundances of some beneficial bacteria and fungi, such as Streptomyces, decreased, while those of plant and animal pathogenic bacteria and fungi, dramatically increased, after EPN treatment. On the other hand, the abundances of some entomopathogenic fungi, such as Fusicolla, Clonostachys, and Mortierella, increased. Redundancy analysis or canonical correspondence analysis revealed a positive correlation between the efficacious EPN control and the presence of the insect-resistant bacteria, Sinomonas, as well as entomopathogenic fungi Fusicolla and Mortierella. This suggests that the interactions between EPN and entomopathogenic fungi may play a role in the biological control of RIFA. Our discoveries shed light on the interactions among EPN, RIFA, and soil microbial communities, and emphasize a possible mutualistic relationship between EPN and entomopathogenic fungi in the biological control of RIFA.
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Affiliation(s)
- Xiaowei Li
- State Key Laboratory for Managing Biotic and Chemical Threats to Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection of MOA of China and Zhejiang Province, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China
| | - Songwang Yi
- State Key Laboratory for Managing Biotic and Chemical Threats to Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection of MOA of China and Zhejiang Province, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China; College of Advanced Agricultural Sciences, Zhejiang A&F University, Hangzhou 311300, China
| | - Limin Chen
- State Key Laboratory for Managing Biotic and Chemical Threats to Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection of MOA of China and Zhejiang Province, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China
| | - Muhammad Hafeez
- State Key Laboratory for Managing Biotic and Chemical Threats to Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection of MOA of China and Zhejiang Province, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China
| | - Zhijun Zhang
- State Key Laboratory for Managing Biotic and Chemical Threats to Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection of MOA of China and Zhejiang Province, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China
| | - Jinming Zhang
- State Key Laboratory for Managing Biotic and Chemical Threats to Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection of MOA of China and Zhejiang Province, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China
| | - Shuxing Zhou
- State Key Laboratory for Managing Biotic and Chemical Threats to Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection of MOA of China and Zhejiang Province, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China
| | - Wanying Dong
- State Key Laboratory for Managing Biotic and Chemical Threats to Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection of MOA of China and Zhejiang Province, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China
| | - Jun Huang
- State Key Laboratory for Managing Biotic and Chemical Threats to Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection of MOA of China and Zhejiang Province, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China.
| | - Yaobin Lu
- State Key Laboratory for Managing Biotic and Chemical Threats to Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection of MOA of China and Zhejiang Province, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China; Institute of Bio-Interaction, Xianghu Laboratory, Hangzhou 311258, China.
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4
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Thakur M, Khushboo, Kumar Y, Yadav V, Pramanik A, Dubey KK. Understanding resistance acquisition by Pseudomonas aeruginosa and possible pharmacological approaches in palliating its pathogenesis. Biochem Pharmacol 2023; 215:115689. [PMID: 37481132 DOI: 10.1016/j.bcp.2023.115689] [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: 05/06/2023] [Revised: 07/03/2023] [Accepted: 07/12/2023] [Indexed: 07/24/2023]
Abstract
Pseudomonas aeruginosa can utilize various virulence factors necessary for host infection and persistence. These virulence factors include pyocyanin, proteases, exotoxins, 2-heptyl-4-hydroxyquinoline N-oxide (HQNO), phospholipases, and siderophores that enable the bacteria to cause severe infections in immunocompromised individuals. P. aeruginosa falls into the category of nosocomial pathogens that are typically resistant to available antibiotics and therapeutic approaches. P. aeruginosa bio-film formation is a major concern in hospitals because it can cause chronic infection and increase the risk of mortality. Therefore, the development of new strategies to disrupt biofilm formation and improve antibiotic efficacy for the treatment of P. aeruginosa infections is crucial. Anti-biofilm and anti-quorum sensing (QS) activity can be viewed as an anti-virulence approach to control the infectious nature of P. aeruginosa. Inhibition of QS and biofilm formation can be achieved through pharmacological approaches such as phytochemicals and essential oils, which have shown promising results in laboratory studies. A regulatory protein called LasR plays a key role in QS signaling to coordinate gene expression. Designing an antagonist molecule that mimics the natural autoinducer might be the best approach for LasR inhibition. Here we reviewed the mechanism behind antibiotic resistance and alternative approaches to combat the pathogenicity of P. aeruginosa.
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Affiliation(s)
- Mony Thakur
- Department of Microbiology, Central University of Haryana, Mahendergarh, Haryana 123031, India
| | - Khushboo
- Department of Biotechnology, Central University of Haryana, Mahendergarh, Haryana 123031, India
| | - Yatin Kumar
- Department of Microbiology, Central University of Haryana, Mahendergarh, Haryana 123031, India
| | - Vinod Yadav
- Department of Microbiology, Central University of Haryana, Mahendergarh, Haryana 123031, India
| | - Avijit Pramanik
- Department of Microbiology, Central University of Haryana, Mahendergarh, Haryana 123031, India
| | - Kashyap Kumar Dubey
- Biomanufacturing and Process Development Laboratory, School of Biotechnology, Jawaharlal Nehru University, New Delhi-67, India.
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5
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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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6
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Otero-Asman JR, Sánchez-Jiménez A, Bastiaansen KC, Wettstadt S, Civantos C, García-Puente A, Bitter W, Llamas MA. The Prc and CtpA proteases modulate cell-surface signaling activity and virulence in Pseudomonas aeruginosa. iScience 2023; 26:107216. [PMID: 37534181 PMCID: PMC10392083 DOI: 10.1016/j.isci.2023.107216] [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: 04/17/2023] [Revised: 05/17/2023] [Accepted: 06/22/2023] [Indexed: 08/04/2023] Open
Abstract
Cell-surface signaling (CSS) is a signal transfer system of Gram-negative bacteria that produces the activation of an extracytoplasmic function σ factor (σECF) in the cytosol in response to an extracellular signal. Activation requires the regulated and sequential proteolysis of the σECF-associated anti-σ factor, and the function of the Prc and RseP proteases. In this work, we have identified another protease that modulates CSS activity, namely the periplasmic carboxyl-terminal processing protease CtpA. CtpA functions upstream of Prc in the proteolytic cascade and seems to prevent the Prc-mediated proteolysis of the CSS anti-σ factor. Importantly, using zebrafish embryos and the A549 lung epithelial cell line as hosts, we show that mutants in the rseP and ctpA proteases of the human pathogen Pseudomonas aeruginosa are considerably attenuated in virulence while the prc mutation increases virulence likely by enhancing the production of membrane vesicles.
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Affiliation(s)
- Joaquín R. Otero-Asman
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, 18008 Granada, Spain
| | - Ana Sánchez-Jiménez
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, 18008 Granada, Spain
| | - Karlijn C. Bastiaansen
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, 18008 Granada, Spain
- Department of Medical Microbiology and Infection Control, Amsterdam University medical centres, location VU University, 1081 HV Amsterdam, The Netherlands
| | - Sarah Wettstadt
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, 18008 Granada, Spain
| | - Cristina Civantos
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, 18008 Granada, Spain
| | - Alicia García-Puente
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, 18008 Granada, Spain
| | - Wilbert Bitter
- Department of Medical Microbiology and Infection Control, Amsterdam University medical centres, location VU University, 1081 HV Amsterdam, The Netherlands
| | - María A. Llamas
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, 18008 Granada, Spain
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7
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Pardue EJ, Sartorio MG, Jana B, Scott NE, Beatty W, Ortiz-Marquez JC, Van Opijnen T, Hsu FF, Potter R, Feldman MF. Dual Membrane-spanning Anti-Sigma Factors Regulate Vesiculation in Gut Bacteroidota. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.13.548920. [PMID: 37503209 PMCID: PMC10369966 DOI: 10.1101/2023.07.13.548920] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Bacteroidota are abundant members of the human gut microbiota that shape the enteric landscape by modulating host immunity and degrading dietary- and host-derived glycans. These processes are at least partially mediated by O uter M embrane V esicles (OMVs). In this work, we developed a high-throughput screen to identify genes required for OMV biogenesis and its regulation in Bacteroides thetaiotaomicron ( Bt ). Our screening led us to the identification of a novel family of D ual M embrane-spanning A nti-sigma factors (Dma), which regulate OMV biogenesis in Bt . We employed molecular and multiomic analyses to demonstrate that deletion of Dma1, the founding member of the Dma family, results in hypervesiculation by modulating the expression of NigD1, which belongs to a family of uncharacterized proteins found throughout Bacteroidota. Dma1 has an unprecedented domain organization: it contains a C-terminal β-barrel embedded in the OM; its N-terminal domain interacts with its cognate sigma factor in the cytoplasm, and both domains are tethered via an intrinsically disordered region that traverses the periplasm. Phylogenetic analyses reveal that the Dma family is a unique feature of Bacteroidota. This study provides the first mechanistic insights into the regulation of OMV biogenesis in human gut bacteria.
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8
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Rey-Varela D, Balado M, Lemos ML. The Sigma Factor AsbI Is Required for the Expression of Acinetobactin Siderophore Transport Genes in Aeromonas salmonicida. Int J Mol Sci 2023; 24:ijms24119672. [PMID: 37298622 DOI: 10.3390/ijms24119672] [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: 04/28/2023] [Revised: 05/30/2023] [Accepted: 05/31/2023] [Indexed: 06/12/2023] Open
Abstract
Aeromonas salmonicida subsp. salmonicida (A. salmonicida), a Gram-negative bacterium causing furunculosis in fish, produces the siderophores acinetobactin and amonabactins in order to extract iron from its hosts. While the synthesis and transport of both systems is well understood, the regulation pathways and conditions necessary for the production of each one of these siderophores are not clear. The acinetobactin gene cluster carries a gene (asbI) encoding a putative sigma factor belonging to group 4 σ factors, or, the ExtraCytoplasmic Function (ECF) group. By generating a null asbI mutant, we demonstrate that AsbI is a key regulator that controls acinetobactin acquisition in A. salmonicida, since it directly regulates the expression of the outer membrane transporter gene and other genes necessary for Fe-acinetobactin transport. Furthermore, AsbI regulatory functions are interconnected with other iron-dependent regulators, such as the Fur protein, as well as with other sigma factors in a complex regulatory network.
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Affiliation(s)
- Diego Rey-Varela
- Departmento de Microbiología y Parasitología, Instituto de Acuicultura, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Miguel Balado
- Departmento de Microbiología y Parasitología, Instituto de Acuicultura, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Manuel L Lemos
- Departmento de Microbiología y Parasitología, Instituto de Acuicultura, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain
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Sánchez-Jiménez A, Marcos-Torres FJ, Llamas MA. Mechanisms of iron homeostasis in Pseudomonas aeruginosa and emerging therapeutics directed to disrupt this vital process. Microb Biotechnol 2023. [PMID: 36857468 DOI: 10.1111/1751-7915.14241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 02/13/2023] [Indexed: 03/03/2023] Open
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen able to infect any human tissue. One of the reasons for its high adaptability and colonization of host tissues is its capacity of maintaining iron homeostasis through a wide array of iron acquisition and removal mechanisms. Due to their ability to cause life-threatening acute and chronic infections, especially among cystic fibrosis and immunocompromised patients, and their propensity to acquire resistance to many antibiotics, the World Health Organization (WHO) has encouraged the scientific community to find new strategies to eradicate this pathogen. Several recent strategies to battle P. aeruginosa focus on targeting iron homeostasis mechanisms, turning its greatest advantage into an exploitable weak point. In this review, we discuss the different mechanisms used by P. aeruginosa to maintain iron homeostasis and the strategies being developed to fight this pathogen by blocking these mechanisms. Among others, the use of iron chelators and mimics, as well as disruption of siderophore production and uptake, have shown promising results in reducing viability and/or virulence of this pathogen. The so-called 'Trojan-horse' strategy taking advantage of the siderophore uptake systems is emerging as an efficient method to improve delivery of antibiotics into the bacterial cells. Moreover, siderophore transporters are considered promising targets for the developing of P. aeruginosa vaccines.
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Affiliation(s)
- Ana Sánchez-Jiménez
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Francisco J Marcos-Torres
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - María A Llamas
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, Granada, Spain
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Teng S, Wu T, Gao D, Wu S, Xiao Y, Long Y, Xie Z. Insight into the Global Negative Regulation of Iron Scavenger 7-HT Biosynthesis by the SigW/RsiW System in Pseudomonas donghuensis HYS. Int J Mol Sci 2023; 24:ijms24021184. [PMID: 36674714 PMCID: PMC9861184 DOI: 10.3390/ijms24021184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2022] [Revised: 01/04/2023] [Accepted: 01/05/2023] [Indexed: 01/11/2023] Open
Abstract
7-Hydroxytropolone (7-HT) is a unique iron scavenger synthesized by Pseudomonas donghuensis HYS that has various biological activities in addition to functioning as a siderophore. P. donghuensis HYS is more pathogenic than P. aeruginosa toward Caenorhabditis elegans, an observation that is closely linked to the biosynthesis of 7-HT. The nonfluorescent siderophore (nfs) gene cluster is responsible for the orderly biosynthesis of 7-HT and represents a competitive advantage that contributes to the increased survival of P. donghuensis HYS; however, the regulatory mechanisms of 7-HT biosynthesis remain unclear. This study is the first to propose that the ECF σ factor has a regulatory effect on 7-HT biosynthesis. In total, 20 ECF σ factors were identified through genome-wide scanning, and their responses to extracellular ferrous ions were characterized. We found that SigW was both significantly upregulated under high-iron conditions and repressed by an adjacent anti-σ factor. RNA-Seq results suggest that the SigW/RsiW system is involved in iron metabolism and 7-HT biosynthesis. Combined with the siderophore phenotype, we also found that SigW could inhibit siderophore synthesis, and this inhibition can be relieved by RsiW. EMSA assays proved that SigW, when highly expressed, can directly bind to the promoter region of five operons of the nfs cluster to inhibit the transcription of the corresponding genes and consequently suppress 7-HT biosynthesis. In addition, SigW not only directly negatively regulates structural genes related to 7-HT synthesis but also inhibits the transcription of regulatory proteins, including of the Gac/Rsm cascade system. Taken together, our results highlight that the biosynthesis of 7-HT is negatively regulated by SigW and that the SigW/RsiW system is involved in mechanisms for the regulation of iron homeostasis in P. donghuensis HYS. As a result of this work, we identified a novel mechanism for the global negative regulation of 7-HT biosynthesis, complementing our understanding of the function of ECF σ factors in Pseudomonas.
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11
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Bernal P, Civantos C, Pacheco-Sánchez D, Quesada JM, Filloux A, Llamas MA. Transcriptional organization and regulation of the Pseudomonas putida K1 type VI secretion system gene cluster. MICROBIOLOGY (READING, ENGLAND) 2023; 169:001295. [PMID: 36748579 PMCID: PMC9993120 DOI: 10.1099/mic.0.001295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The type VI secretion system (T6SS) is an antimicrobial molecular weapon that is widespread in Proteobacteria and offers competitive advantages to T6SS-positive micro-organisms. Three T6SSs have recently been described in Pseudomonas putida KT2440 and it has been shown that one, K1-T6SS, is used to outcompete a wide range of phytopathogens, protecting plants from pathogen infections. Given the relevance of this system as a powerful and innovative mechanism of biological control, it is critical to understand the processes that govern its expression. Here, we experimentally defined two transcriptional units in the K1-T6SS cluster. One encodes the structural components of the system and is transcribed from two adjacent promoters. The other encodes two hypothetical proteins, the tip of the system and the associated adapters, and effectors and cognate immunity proteins, and it is also transcribed from two adjacent promoters. The four identified promoters contain the typical features of σ70-dependent promoters. We have studied the expression of the system under different conditions and in a number of mutants lacking global regulators. P. putida K1-T6SS expression is induced in the stationary phase, but its transcription does not depend on the stationary σ factor RpoS. In fact, the expression of the system is indirectly repressed by RpoS. Furthermore, it is also repressed by RpoN and the transcriptional regulator FleQ, an enhancer-binding protein typically acting in conjunction with RpoN. Importantly, expression of the K1-T6SS gene cluster is positively regulated by the GacS-GacA two-component regulatory system (TCS) and repressed by the RetS sensor kinase, which inhibits this TCS. Our findings identified a complex regulatory network that governs T6SS expression in general and P. putida K1-T6SS in particular, with implications for controlling and manipulating a bacterial agent that is highly relevant in biological control.
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Affiliation(s)
- Patricia Bernal
- Department of Environmental Protection, Estación Experimental del Zaidín (CSIC), Granada, Spain.,MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London, UK.,Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, 41012 Seville, Spain
| | - Cristina Civantos
- Department of Environmental Protection, Estación Experimental del Zaidín (CSIC), Granada, Spain
| | - Daniel Pacheco-Sánchez
- Department of Environmental Protection, Estación Experimental del Zaidín (CSIC), Granada, Spain
| | - José M Quesada
- Department of Environmental Protection, Estación Experimental del Zaidín (CSIC), Granada, Spain
| | - Alain Filloux
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London, UK.,Singapore Centre for Environmental Life Sciences Engineering. Nanyang Technological University, Singapore
| | - María A Llamas
- Department of Environmental Protection, Estación Experimental del Zaidín (CSIC), Granada, Spain
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12
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High-Level Expression of Cell-Surface Signaling System Hxu Enhances Pseudomonas aeruginosa Bloodstream Infection. Infect Immun 2022; 90:e0032922. [PMID: 36169312 PMCID: PMC9584290 DOI: 10.1128/iai.00329-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bloodstream infections (BSIs) caused by Pseudomonas aeruginosa are associated with a high mortality rate in the clinic. However, the fitness mechanisms responsible for the evolution of virulence factors that facilitate the dissemination of P. aeruginosa to the bloodstream are poorly understood. In this study, a transcriptomic analysis of the BSI-associated P. aeruginosa clinical isolates showed a high-level expression of cell-surface signaling (CSS) system Hxu. Whole-genome sequencing and comparative genomics of these isolates showed that a mutation in rnfE gene was responsible for the elevated expression of the Hxu-CSS pathway. Most importantly, deletion of the hxuIRA gene cluster in a laboratory strain PAO1 reduced its BSI capability while overexpression of the HxuIRA pathway promoted BSI in a murine sepsis model. We further demonstrated that multiple components in the blood plasma, including heme, hemoglobin, the heme-scavenging proteins haptoglobin, and hemopexin, as well as the iron-delivery protein transferrin, could activate the Hxu system. Together, these studies suggested that the Hxu-CSS system was an important signal transduction pathway contributing to the adaptive pathogenesis of P. aeruginosa in BSI.
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An Extracytoplasmic Function Sigma Factor Required for Full Virulence in Xanthomonas citri pv. citri. J Bacteriol 2022; 204:e0062421. [PMID: 35446118 DOI: 10.1128/jb.00624-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The genus Xanthomonas includes more than 30 phytopathogenic species that infect a wide range of plants and cause severe diseases that greatly impact crop productivity. These bacteria are highly adapted to the soil and plant environment, being found in decaying material, as epiphytes, and colonizing the plant mesophyll. Signal transduction mechanisms involved in the responses of Xanthomonas to environmental changes are still poorly characterized. Xanthomonad genomes typically encode several representatives of the extracytoplasmic function σ (σECF) factors, whose physiological roles remain elusive. In this work, we functionally characterized the Xanthomonas citri pv. citri EcfL, a σECF factor homologous to members of the iron-responsive FecI-like group. We show that EcfL is not required or induced during iron starvation, despite presenting the common features of other FecI-like σECF factors. EcfL positively regulates one operon composed of three genes that encode a TonB-dependent receptor involved in cell surface signaling, an acid phosphatase, and a lectin-domain containing protein. Furthermore, we demonstrate that EcfL is required for full virulence in citrus, and its regulon is induced inside the plant mesophyll and in response to acid stress. Together, our study suggests a role for EcfL in the adaptation of X. citri to the plant environment, in this way contributing to its ability to cause citrus canker disease. IMPORTANCE The Xanthomonas genus comprises a large number of phytopathogenic species that infect a wide variety of economically important plants worldwide. Bacterial adaptation to the plant and soil environment relies on their repertoire of signal transduction pathways, including alternative sigma factors of the extracytoplasmic function family (σECF). Here, we describe a new σECF factor found in several Xanthomonas species, demonstrating its role in Xanthomonas citri virulence to citrus plants. We show that EcfL regulates a single operon containing three genes, which are also conserved in other Xanthomonas species. This study further expands our knowledge on the functions of the widespread family of σECF factors in phytopathogenic bacteria.
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Marcos-Torres FJ, Moraleda-Muñoz A, Contreras-Moreno FJ, Muñoz-Dorado J, Pérez J. Mechanisms of Action of Non-Canonical ECF Sigma Factors. Int J Mol Sci 2022; 23:ijms23073601. [PMID: 35408957 PMCID: PMC8999054 DOI: 10.3390/ijms23073601] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 03/23/2022] [Accepted: 03/24/2022] [Indexed: 02/04/2023] Open
Abstract
Extracytoplasmic function (ECF) sigma factors are subunits of the RNA polymerase specialized in activating the transcription of a subset of genes responding to a specific environmental condition. The signal-transduction pathways where they participate can be activated by diverse mechanisms. The most common mechanism involves the action of a membrane-bound anti-sigma factor, which sequesters the ECF sigma factor, and releases it after the stimulus is sensed. However, despite most of these systems following this canonical regulation, there are many ECF sigma factors exhibiting a non-canonical regulatory mechanism. In this review, we aim to provide an updated and comprehensive view of the different activation mechanisms known for non-canonical ECF sigma factors, detailing their inclusion to the different phylogenetic groups and describing the mechanisms of regulation of some of their representative members such as EcfG from Rhodobacter sphaeroides, showing a partner-switch mechanism; EcfP from Vibrio parahaemolyticus, with a phosphorylation-dependent mechanism; or CorE from Myxococcus xanthus, regulated by a metal-sensing C-terminal extension.
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Affiliation(s)
| | - Aurelio Moraleda-Muñoz
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada, Avda, Fuentenueva s/n, 18071 Granada, Spain; (F.J.C.-M.); (J.M.-D.)
- Correspondence: (A.M.-M.); (J.P.); Tel.: +34-95-824-2858 (A.M.-M.); +34-95-824-9830 (J.P.)
| | - Francisco Javier Contreras-Moreno
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada, Avda, Fuentenueva s/n, 18071 Granada, Spain; (F.J.C.-M.); (J.M.-D.)
| | - José Muñoz-Dorado
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada, Avda, Fuentenueva s/n, 18071 Granada, Spain; (F.J.C.-M.); (J.M.-D.)
| | - Juana Pérez
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada, Avda, Fuentenueva s/n, 18071 Granada, Spain; (F.J.C.-M.); (J.M.-D.)
- Correspondence: (A.M.-M.); (J.P.); Tel.: +34-95-824-2858 (A.M.-M.); +34-95-824-9830 (J.P.)
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15
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Monteagudo-Cascales E, Santero E, Canosa I. The Regulatory Hierarchy Following Signal Integration by the CbrAB Two-Component System: Diversity of Responses and Functions. Genes (Basel) 2022; 13:genes13020375. [PMID: 35205417 PMCID: PMC8871633 DOI: 10.3390/genes13020375] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 02/14/2022] [Accepted: 02/16/2022] [Indexed: 02/04/2023] Open
Abstract
CbrAB is a two-component system, unique to bacteria of the family Pseudomonaceae, capable of integrating signals and involved in a multitude of physiological processes that allow bacterial adaptation to a wide variety of varying environmental conditions. This regulatory system provides a great metabolic versatility that results in excellent adaptability and metabolic optimization. The two-component system (TCS) CbrA-CbrB is on top of a hierarchical regulatory cascade and interacts with other regulatory systems at different levels, resulting in a robust output. Among the regulatory systems found at the same or lower levels of CbrAB are the NtrBC nitrogen availability adaptation system, the Crc/Hfq carbon catabolite repression cascade in Pseudomonas, or interactions with the GacSA TCS or alternative sigma ECF factor, such as SigX. The interplay between regulatory mechanisms controls a number of physiological processes that intervene in important aspects of bacterial adaptation and survival. These include the hierarchy in the use of carbon sources, virulence or resistance to antibiotics, stress response or definition of the bacterial lifestyle. The multiple actions of the CbrAB TCS result in an important competitive advantage.
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Affiliation(s)
| | - Eduardo Santero
- Departamento de Biología Molecular e Ingeniería Bioquímica, Universidad Pablo de Olavide, Centro Andaluz de Biología del Desarrollo, CSIC, Junta de Andalucía, 41013 Seville, Spain;
| | - Inés Canosa
- Departamento de Biología Molecular e Ingeniería Bioquímica, Universidad Pablo de Olavide, Centro Andaluz de Biología del Desarrollo, CSIC, Junta de Andalucía, 41013 Seville, Spain;
- Correspondence: ; Tel.: +34-954349052
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Braun V, Hartmann MD, Hantke K. Transcription regulation of iron carrier transport genes by ECF sigma factors through signaling from the cell surface into the cytoplasm. FEMS Microbiol Rev 2022; 46:6524835. [PMID: 35138377 PMCID: PMC9249621 DOI: 10.1093/femsre/fuac010] [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] [Received: 05/28/2021] [Revised: 01/26/2022] [Accepted: 02/07/2022] [Indexed: 12/02/2022] Open
Abstract
Bacteria are usually iron-deficient because the Fe3+ in their environment is insoluble or is incorporated into proteins. To overcome their natural iron limitation, bacteria have developed sophisticated iron transport and regulation systems. In gram-negative bacteria, these include iron carriers, such as citrate, siderophores, and heme, which when loaded with Fe3+ adsorb with high specificity and affinity to outer membrane proteins. Binding of the iron carriers to the cell surface elicits a signal that initiates transcription of iron carrier transport and synthesis genes, referred to as “cell surface signaling”. Transcriptional regulation is not coupled to transport. Outer membrane proteins with signaling functions contain an additional N-terminal domain that in the periplasm makes contact with an anti-sigma factor regulatory protein that extends from the outer membrane into the cytoplasm. Binding of the iron carriers to the outer membrane receptors elicits proteolysis of the anti-sigma factor by two different proteases, Prc in the periplasm, and RseP in the cytoplasmic membrane, inactivates the anti-sigma function or results in the generation of an N-terminal peptide of ∼50 residues with pro-sigma activity yielding an active extracytoplasmic function (ECF) sigma factor. Signal recognition and signal transmission into the cytoplasm is discussed herein.
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Affiliation(s)
- Volkmar Braun
- Max Planck Institute for Biology, Department of Protein Evolution, Max Planck Ring 5, 72076 Tübingen, Germany
| | - Marcus D Hartmann
- Max Planck Institute for Biology, Department of Protein Evolution, Max Planck Ring 5, 72076 Tübingen, Germany
| | - Klaus Hantke
- IMIT Institute, University of Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, Germany
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17
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Iron Homeostasis in Pseudomonas aeruginosa: Targeting Iron Acquisition and Storage as an Antimicrobial Strategy. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1386:29-68. [DOI: 10.1007/978-3-031-08491-1_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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18
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Extracellular haem utilization by the opportunistic pathogen Pseudomonas aeruginosa and its role in virulence and pathogenesis. Adv Microb Physiol 2021; 79:89-132. [PMID: 34836613 DOI: 10.1016/bs.ampbs.2021.07.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Iron is an essential micronutrient for all bacteria but presents a significant challenge given its limited bioavailability. Furthermore, iron's toxicity combined with the need to maintain iron levels within a narrow physiological range requires integrated systems to sense, regulate and transport a variety of iron complexes. Most bacteria encode systems to chelate and transport ferric iron (Fe3+) via siderophore receptor mediated uptake or via cytoplasmic energy dependent transport systems. Pathogenic bacteria have further lowered the barrier to iron acquisition by employing systems to utilize haem as a source of iron. Haem, a lipophilic and toxic molecule, presents a significant challenge for transport into the cell. As such pathogenic bacteria have evolved sophisticated cell surface signaling (CSS) and transport systems to sense and obtain haem from the host. Once internalized haem is cleaved by both oxidative and non-oxidative mechanisms to release iron. Herein we summarize our current understanding of the mechanism of haem sensing, uptake and utilization in Pseudomonas aeruginosa, its role in pathogenesis and virulence, and the potential of these systems as antimicrobial targets.
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19
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Chadha J, Harjai K, Chhibber S. Revisiting the virulence hallmarks of Pseudomonas aeruginosa: a chronicle through the perspective of quorum sensing. Environ Microbiol 2021; 24:2630-2656. [PMID: 34559444 DOI: 10.1111/1462-2920.15784] [Citation(s) in RCA: 63] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 09/16/2021] [Accepted: 09/17/2021] [Indexed: 12/15/2022]
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen and the leading cause of mortality among immunocompromised patients in clinical setups. The hallmarks of virulence in P. aeruginosa encompass six biologically competent attributes that cumulatively drive disease progression in a multistep manner. These multifaceted hallmarks lay the principal foundation for rationalizing the complexities of pseudomonal infections. They include factors for host colonization and bacterial motility, biofilm formation, production of destructive enzymes, toxic secondary metabolites, iron-chelating siderophores and toxins. This arsenal of virulence hallmarks is fostered and stringently regulated by the bacterial signalling system called quorum sensing (QS). The central regulatory functions of QS in controlling the timely expression of these virulence hallmarks for adaptation and survival drive the disease outcome. This review describes the intricate mechanisms of QS in P. aeruginosa and its role in shaping bacterial responses, boosting bacterial fitness. We summarize the virulence hallmarks of P. aeruginosa, relating them with the QS circuitry in clinical infections. We also examine the role of QS in the development of drug resistance and propose a novel antivirulence therapy to combat P. aeruginosa infections. This can prove to be a next-generation therapy that may eventually become refractory to the use of conventional antimicrobial treatments.
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Affiliation(s)
- Jatin Chadha
- Department of Microbiology, Panjab University, Chandigarh, India
| | - Kusum Harjai
- Department of Microbiology, Panjab University, Chandigarh, India
| | - Sanjay Chhibber
- Department of Microbiology, Panjab University, Chandigarh, India
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20
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Craig K, Johnson BR, Grunden A. Leveraging Pseudomonas Stress Response Mechanisms for Industrial Applications. Front Microbiol 2021; 12:660134. [PMID: 34040596 PMCID: PMC8141521 DOI: 10.3389/fmicb.2021.660134] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 04/12/2021] [Indexed: 12/25/2022] Open
Abstract
Members of the genus Pseudomonas are metabolically versatile and capable of adapting to a wide variety of environments. Stress physiology of Pseudomonas strains has been extensively studied because of their biotechnological potential in agriculture as well as their medical importance with regards to pathogenicity and antibiotic resistance. This versatility and scientific relevance led to a substantial amount of information regarding the stress response of a diverse set of species such as Pseudomonas chlororaphis, P. fluorescens, P. putida, P. aeruginosa, and P. syringae. In this review, environmental and industrial stressors including desiccation, heat, and cold stress, are cataloged along with their corresponding mechanisms of survival in Pseudomonas. Mechanisms of survival are grouped by the type of inducing stress with a focus on adaptations such as synthesis of protective substances, biofilm formation, entering a non-culturable state, enlisting chaperones, transcription and translation regulation, and altering membrane composition. The strategies Pseudomonas strains utilize for survival can be leveraged during the development of beneficial strains to increase viability and product efficacy.
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Affiliation(s)
- Kelly Craig
- AgBiome Inc., Research Triangle Park, NC, United States
| | | | - Amy Grunden
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC, United States
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21
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Valenzuela‐Heredia D, Henríquez‐Castillo C, Donoso R, Lavín P, Ringel MT, Brüser T, Campos JL. An unusual overrepresentation of genetic factors related to iron homeostasis in the genome of the fluorescent Pseudomonas sp. ABC1. Microb Biotechnol 2021; 14:1060-1072. [PMID: 33492712 PMCID: PMC8085936 DOI: 10.1111/1751-7915.13753] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 12/29/2020] [Accepted: 01/02/2021] [Indexed: 12/25/2022] Open
Abstract
Members of the genus Pseudomonas inhabit diverse environments, such as soil, water, plants and humans. The variability of habitats is reflected in the diversity of the structure and composition of their genomes. This cosmopolitan bacterial genus includes species of biotechnological, medical and environmental importance. In this study, we report on the most relevant genomic characteristics of Pseudomonas sp. strain ABC1, a siderophore-producing fluorescent strain recently isolated from soil. Phylogenomic analyses revealed that this strain corresponds to a novel species forming a sister clade of the recently proposed Pseudomonas kirkiae. The genomic information reveals an overrepresented repertoire of mechanisms to hoard iron when compared to related strains, including a high representation of fecI-fecR family genes related to iron regulation and acquisition. The genome of the Pseudomonas sp. ABC1 contains the genes for non-ribosomal peptide synthetases (NRPSs) of a novel putative Azotobacter-related pyoverdine-type siderophore, a yersiniabactin-type siderophore and an antimicrobial betalactone; the last two are found only in a limited number of Pseudomonas genomes. Strain ABC1 can produce siderophores in a low-cost medium, and the supernatants from cultures of this strain promote plant growth, highlighting their biotechnological potential as a sustainable industrial microorganism.
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Affiliation(s)
| | - Carlos Henríquez‐Castillo
- Laboratorio de Fisiología y Genética Marina (FIGEMA)Centro de Estudios Avanzados de Zonas Áridas (CEAZA)CoquimboChile
- Facultad de Ciencias del MarUniversidad Católica del NorteCoquimboChile
| | - Raúl Donoso
- Programa Institucional de Fomento a la InvestigaciónDesarrollo, e Innovación (PIDi)Universidad Tecnológica MetropolitanaSantiagoChile
| | - Paris Lavín
- Facultad de Ciencias del Mar y Recursos BiológicosDepartamento de BiotecnologíaLaboratorio de Complejidad Microbiana y Ecología FuncionalInstituto AntofagastaUniversidad de AntofagastaAntofagastaChile
- Network for Extreme Environments Research (NEXER)Universidad de AntofagastaUniversidad de La Frontera y Universidad de MagallanesPunta ArenasChile
| | | | - Thomas Brüser
- Institute of MicrobiologyLeibniz University HannoverHannoverGermany
| | - José Luis Campos
- Facultad de Ingeniería y CienciasUniversidad Adolfo IbáñezViña del MarChile
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22
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An extracytoplasmic function (ECF) sigma/anti-sigma factor system regulates hypochlorous acid resistance and impacts expression of the type IV secretion system in Brucella melitensis. J Bacteriol 2021; 203:e0012721. [PMID: 33820796 PMCID: PMC8315932 DOI: 10.1128/jb.00127-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The intracellular bacterial pathogen Brucella causes persistent infections in various mammalian species. To survive and replicate within macrophages, these bacteria must be able to withstand oxidative stresses and express the type IV secretion system (T4SS) to evade host immune responses. The extracytoplasmic function (ECF) sigma factor system is a major signal transduction mechanism in bacteria that senses environmental cues and responds by regulating gene expression. In this study, we defined an ECF σ bcrS and its cognate anti-σ factor abcS in Brucella melitensis M28 by conserved domain analysis and a protein interaction assay. BcrS directly activates an adjacent operon, bcrXQP, that encodes a methionine-rich peptide and a putative methionine sulfoxide reductase system, whereas AbcS is a negative regulator of bcrS and bcrXQP. The bcrS-abcS and bcrXQP operons can be induced by hypochlorous acid and contribute to hypochlorous acid resistance in vitro. Next, RNA sequencing analysis and genome-wide recognition sequence search identified the regulons of BcrS and AbcS. Interestingly, we found that BcrS positively influences T4SS expression in an AbcS-dependent manner and that AbcS also affects T4SS expression independently of BcrS. Last, we demonstrate that abcS is required for the maintenance of persistent infection, while bcrS is dispensable in a mouse infection model. Collectively, we conclude that BcrS and AbcS influence expression of multiple genes responsible for Brucella virulence traits. IMPORTANCEBrucella is a notorious intracellular pathogen that induces chronic infections in animals and humans. To survive and replicate within macrophages, these bacteria require a capacity to withstand oxidative stresses and to express the type IV secretion system (T4SS) to combat host immune responses. In this study, we characterized an extracytoplasmic function sigma/anti-sigma factor system that regulates resistance to reactive chlorine species and T4SS expression, thereby establishing a potential link between two crucial virulence traits of Brucella. Furthermore, the anti-sigma factor AbcS contributes to Brucella persistent infection of mice. Thus, this work provides novel insights into Brucella virulence regulation as well as a potential drug target for fighting Brucella infections.
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23
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Wettstadt S, Llamas MA. Role of Regulated Proteolysis in the Communication of Bacteria With the Environment. Front Mol Biosci 2020; 7:586497. [PMID: 33195433 PMCID: PMC7593790 DOI: 10.3389/fmolb.2020.586497] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 09/22/2020] [Indexed: 12/29/2022] Open
Abstract
For bacteria to flourish in different niches, they need to sense signals from the environment and translate these into appropriate responses. Most bacterial signal transduction systems involve proteins that trigger the required response through the modification of gene transcription. These proteins are often produced in an inactive state that prevents their interaction with the RNA polymerase and/or the DNA in the absence of the inducing signal. Among other mechanisms, regulated proteolysis is becoming increasingly recognized as a key process in the modulation of the activity of these signal response proteins. Regulated proteolysis can either produce complete degradation or specific cleavage of the target protein, thus modifying its function. Because proteolysis is a fast process, the modulation of signaling proteins activity by this process allows for an immediate response to a given signal, which facilitates adaptation to the surrounding environment and bacterial survival. Moreover, regulated proteolysis is a fundamental process for the transmission of extracellular signals to the cytosol through the bacterial membranes. By a proteolytic mechanism known as regulated intramembrane proteolysis (RIP) transmembrane proteins are cleaved within the plane of the membrane to liberate a cytosolic domain or protein able to modify gene transcription. This allows the transmission of a signal present on one side of a membrane to the other side where the response is elicited. In this work, we review the role of regulated proteolysis in the bacterial communication with the environment through the modulation of the main bacterial signal transduction systems, namely one- and two-component systems, and alternative σ factors.
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Affiliation(s)
- Sarah Wettstadt
- Department of Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - María A Llamas
- Department of Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, Granada, Spain
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24
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Veyrier FJ, Nieves C, Lefrancois LH, Trigui H, Vincent AT, Behr MA. RskA Is a Dual Function Activator-Inhibitor That Controls SigK Activity Across Distinct Bacterial Genera. Front Microbiol 2020; 11:558166. [PMID: 33013790 PMCID: PMC7509140 DOI: 10.3389/fmicb.2020.558166] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 08/14/2020] [Indexed: 01/25/2023] Open
Abstract
It has been previously shown that RskA, the anti-Sigma factor K of Mycobacterium tuberculosis, inhibits SigK and that mutations in RskA promote high expression of the SigK regulon. The latter observation led us to hypothesize that RskA mutations lead to loss of the anti-Sigma factor function. In this report, we used natural and artificial mutations in RskA to determine the basis of the SigK-RskA partnership. Consistent with predictions, the N-terminal cytoplasmic portion of RskA was sufficient on its own to inhibit SigK. Unexpectedly, RskA also served as an activator of SigK. This activation depended on the same N-terminal region and was enhanced by the membrane-extracellular portion of RskA. Based on this, we engineered similar truncations in a Gram-negative bacterium, namely Yersinia enterocolitica. Again, we observed that, with specific alterations of RskA, we were able to enhance SigK activity. Together these results support an alternative mechanism of anti-Sigma factor function, that we could term modulator (activator-inhibitor) in both Actinobacteria and Gram-negative bacteria, suggesting that Sigma factor activation by anti-Sigma factors could be under-recognized.
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Affiliation(s)
- Frédéric J Veyrier
- Bacterial Symbionts Evolution, Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique, Université du Québec, Laval, QC, Canada
- McGill International TB Centre, Montreal, QC, Canada
| | - Cecilia Nieves
- Bacterial Symbionts Evolution, Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique, Université du Québec, Laval, QC, Canada
- McGill International TB Centre, Montreal, QC, Canada
| | - Louise H Lefrancois
- McGill International TB Centre, Montreal, QC, Canada
- Department of Medicine, McGill University, Montreal, QC, Canada
| | - Hana Trigui
- Bacterial Symbionts Evolution, Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique, Université du Québec, Laval, QC, Canada
- McGill International TB Centre, Montreal, QC, Canada
| | - Antony T Vincent
- Bacterial Symbionts Evolution, Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique, Université du Québec, Laval, QC, Canada
- McGill International TB Centre, Montreal, QC, Canada
| | - Marcel A Behr
- McGill International TB Centre, Montreal, QC, Canada
- Department of Medicine, McGill University, Montreal, QC, Canada
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Tahrioui A, Ortiz S, Azuama OC, Bouffartigues E, Benalia N, Tortuel D, Maillot O, Chemat S, Kritsanida M, Feuilloley M, Orange N, Michel S, Lesouhaitier O, Cornelis P, Grougnet R, Boutefnouchet S, Chevalier S. Membrane-Interactive Compounds From Pistacia lentiscus L. Thwart Pseudomonas aeruginosa Virulence. Front Microbiol 2020; 11:1068. [PMID: 32528451 PMCID: PMC7264755 DOI: 10.3389/fmicb.2020.01068] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Accepted: 04/29/2020] [Indexed: 12/22/2022] Open
Abstract
Pseudomonas aeruginosa is capable to deploy a collection of virulence factors that are not only essential for host infection and persistence, but also to escape from the host immune system and to become more resistant to drug therapies. Thus, developing anti-virulence agents that may directly counteract with specific virulence factors or disturb higher regulatory pathways controlling the production of virulence armories are urgently needed. In this regard, this study reports that Pistacia lentiscus L. fruit cyclohexane extract (PLFE1) thwarts P. aeruginosa virulence by targeting mainly the pyocyanin pigment production by interfering with 4-hydroxy-2-alkylquinolines molecules production. Importantly, the anti-virulence activity of PLFE1 appears to be associated with membrane homeostasis alteration through the modulation of SigX, an extracytoplasmic function sigma factor involved in cell wall stress response. A thorough chemical analysis of PLFE1 allowed us to identify the ginkgolic acid (C17:1) and hydroginkgolic acid (C15:0) as the main bioactive membrane-interactive compounds responsible for the observed increased membrane stiffness and anti-virulence activity against P. aeruginosa. This study delivers a promising perspective for the potential future use of PLFE1 or ginkgolic acid molecules as an adjuvant therapy to fight against P. aeruginosa infections.
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Affiliation(s)
- Ali Tahrioui
- Laboratoire de Microbiologie Signaux et Microenvironnement, LMSM EA4312, Université de Rouen Normandie, Normandie Université, Évreux, France
| | - Sergio Ortiz
- CiTCoM UMR 8038 CNRS, Faculté des Sciences Pharmaceutiques et Biologiques, Équipe Produits Naturels, Analyses et Synthèses (PNAS), Université Paris Descartes, Paris, France
| | - Onyedikachi Cecil Azuama
- Laboratoire de Microbiologie Signaux et Microenvironnement, LMSM EA4312, Université de Rouen Normandie, Normandie Université, Évreux, France
| | - Emeline Bouffartigues
- Laboratoire de Microbiologie Signaux et Microenvironnement, LMSM EA4312, Université de Rouen Normandie, Normandie Université, Évreux, France
| | - Nabiha Benalia
- CiTCoM UMR 8038 CNRS, Faculté des Sciences Pharmaceutiques et Biologiques, Équipe Produits Naturels, Analyses et Synthèses (PNAS), Université Paris Descartes, Paris, France
| | - Damien Tortuel
- Laboratoire de Microbiologie Signaux et Microenvironnement, LMSM EA4312, Université de Rouen Normandie, Normandie Université, Évreux, France
| | - Olivier Maillot
- Laboratoire de Microbiologie Signaux et Microenvironnement, LMSM EA4312, Université de Rouen Normandie, Normandie Université, Évreux, France
| | - Smain Chemat
- Centre de Recherche Scientifique et Technique en Analyses Physico-Chimiques, CRAPC, Bou Ismaïl, Algeria
| | - Marina Kritsanida
- CiTCoM UMR 8038 CNRS, Faculté des Sciences Pharmaceutiques et Biologiques, Équipe Produits Naturels, Analyses et Synthèses (PNAS), Université Paris Descartes, Paris, France
| | - Marc Feuilloley
- Laboratoire de Microbiologie Signaux et Microenvironnement, LMSM EA4312, Université de Rouen Normandie, Normandie Université, Évreux, France
| | - Nicole Orange
- Laboratoire de Microbiologie Signaux et Microenvironnement, LMSM EA4312, Université de Rouen Normandie, Normandie Université, Évreux, France
| | - Sylvie Michel
- CiTCoM UMR 8038 CNRS, Faculté des Sciences Pharmaceutiques et Biologiques, Équipe Produits Naturels, Analyses et Synthèses (PNAS), Université Paris Descartes, Paris, France
| | - Olivier Lesouhaitier
- Laboratoire de Microbiologie Signaux et Microenvironnement, LMSM EA4312, Université de Rouen Normandie, Normandie Université, Évreux, France
| | - Pierre Cornelis
- Laboratoire de Microbiologie Signaux et Microenvironnement, LMSM EA4312, Université de Rouen Normandie, Normandie Université, Évreux, France
| | - Raphaël Grougnet
- CiTCoM UMR 8038 CNRS, Faculté des Sciences Pharmaceutiques et Biologiques, Équipe Produits Naturels, Analyses et Synthèses (PNAS), Université Paris Descartes, Paris, France
| | - Sabrina Boutefnouchet
- CiTCoM UMR 8038 CNRS, Faculté des Sciences Pharmaceutiques et Biologiques, Équipe Produits Naturels, Analyses et Synthèses (PNAS), Université Paris Descartes, Paris, France
| | - Sylvie Chevalier
- Laboratoire de Microbiologie Signaux et Microenvironnement, LMSM EA4312, Université de Rouen Normandie, Normandie Université, Évreux, France
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26
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Otero-Asman JR, Quesada JM, Jim KK, Ocampo-Sosa A, Civantos C, Bitter W, Llamas MA. The extracytoplasmic function sigma factor σ VreI is active during infection and contributes to phosphate starvation-induced virulence of Pseudomonas aeruginosa. Sci Rep 2020; 10:3139. [PMID: 32081993 PMCID: PMC7035377 DOI: 10.1038/s41598-020-60197-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2019] [Accepted: 02/07/2020] [Indexed: 12/27/2022] Open
Abstract
The extracytoplasmic function sigma factor σVreI of the human pathogen Pseudomonas aeruginosa promotes transcription of potential virulence determinants, including secretion systems and secreted proteins. Its activity is modulated by the VreR anti-σ factor that inhibits the binding of σVreI to the RNA polymerase in the absence of a (still unknown) inducing signal. The vreI-vreR genes are expressed under inorganic phosphate (Pi) starvation, a physiological condition often encountered in the host that increases P. aeruginosa pathogenicity. However, whether or not σVreI is active in vivo during infection and contributes to the Pi starvation-induced virulence of this pathogen has not been analyzed yet. Using zebrafish embryos and a human alveolar basal epithelial cell line as P. aeruginosa hosts, we demonstrate in this work that σVreI is active during infection and that lack of σVreI considerably reduces the Pi starvation-induced virulence of this pathogen. Surprisingly, lack of the σVreI inhibitor, the VreR anti-σ factor, also diminishes the virulence of P. aeruginosa. By transcriptomic analyses we show that VreR modulates gene expression not only in a σVreI-dependent but also in a σVreI-independent manner. This includes potential virulence determinants and transcriptional regulators that could be responsible for the reduced virulence of the ΔvreR mutant.
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Affiliation(s)
- Joaquín R Otero-Asman
- Department of Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - José M Quesada
- Department of Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Kin K Jim
- Department of Medical Microbiology and Infection Control, Amsterdam University medical centers, location VU University, Amsterdam, The Netherlands
| | - Alain Ocampo-Sosa
- Service of Microbiology, Hospital Universitario Marqués de Valdecilla-Instituto de Investigación Sanitaria Valdecilla, Santander, Spain
| | - Cristina Civantos
- Department of Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Wilbert Bitter
- Department of Medical Microbiology and Infection Control, Amsterdam University medical centers, location VU University, Amsterdam, The Netherlands
| | - María A Llamas
- Department of Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, Granada, Spain.
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Otero-Asman JR, García-García AI, Civantos C, Quesada JM, Llamas MA. Pseudomonas aeruginosa possesses three distinct systems for sensing and using the host molecule haem. Environ Microbiol 2019; 21:4629-4647. [PMID: 31390127 DOI: 10.1111/1462-2920.14773] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 08/05/2019] [Indexed: 12/18/2022]
Abstract
Pathogens have developed several strategies to obtain iron during infection, including the use of iron-containing molecules from the host. Haem accounts for the vast majority of the iron pool in vertebrates and thus represents an important source of iron for pathogens. Using a proteomic approach, we have identified in this work a previously uncharacterized system, which we name Hxu, that together with the known Has and Phu systems, is used by the human pathogen Pseudomonas aeruginosa to respond to haem. We show that the Has and Hxu systems are functional signal transduction pathways of the cell-surface signalling class and report the mechanism triggering the activation of these signalling systems. Both signalling cascades involve an outer membrane receptor (HasR and HxuA respectively) that upon sensing haem in the extracellular medium produces the activation of an σECF factor in the cytosol. HxuA has a major role in signalling and a minor role in haem acquisition in conditions in which the HasR and PhuR receptors or other sources of iron are present. Remarkably, P. aeruginosa compensates the lack of the HasR receptor by increasing the production of HxuA, which underscores the importance of haem signalling for this pathogen.
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Affiliation(s)
- Joaquín R Otero-Asman
- Department of Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, 18008, Granada, Spain
| | - Ana I García-García
- Department of Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, 18008, Granada, Spain
| | - Cristina Civantos
- Department of Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, 18008, Granada, Spain
| | - José M Quesada
- Department of Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, 18008, Granada, Spain
| | - María A Llamas
- Department of Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, 18008, Granada, Spain
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Moraleda-Muñoz A, Marcos-Torres FJ, Pérez J, Muñoz-Dorado J. Metal-responsive RNA polymerase extracytoplasmic function (ECF) sigma factors. Mol Microbiol 2019; 112:385-398. [PMID: 31187912 PMCID: PMC6851896 DOI: 10.1111/mmi.14328] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/07/2019] [Indexed: 01/02/2023]
Abstract
In order to survive, bacteria must adapt to multiple fluctuations in their environment, including coping with changes in metal concentrations. Many metals are essential for viability, since they act as cofactors of indispensable enzymes. But on the other hand, they are potentially toxic because they generate reactive oxygen species or displace other metals from proteins, turning them inactive. This dual effect of metals forces cells to maintain homeostasis using a variety of systems to import and export them. These systems are usually inducible, and their expression is regulated by metal sensors and signal‐transduction mechanisms, one of which is mediated by extracytoplasmic function (ECF) sigma factors. In this review, we have focused on the metal‐responsive ECF sigma factors, several of which are activated by iron depletion (FecI, FpvI and PvdS), while others are activated by excess of metals such as nickel and cobalt (CnrH), copper (CarQ and CorE) or cadmium and zinc (CorE2). We focus particularly on their physiological roles, mechanisms of action and signal transduction pathways.
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Affiliation(s)
- Aurelio Moraleda-Muñoz
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada, Avda. Fuentenueva s/n, Granada, E-18071, Spain
| | - Francisco Javier Marcos-Torres
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada, Avda. Fuentenueva s/n, Granada, E-18071, Spain.,Department of Cell and Molecular Biology, Uppsala University, Uppsala, 751 24, Sweden
| | - Juana Pérez
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada, Avda. Fuentenueva s/n, Granada, E-18071, Spain
| | - José Muñoz-Dorado
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada, Avda. Fuentenueva s/n, Granada, E-18071, Spain
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