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George M, Narayanan S, Tejada-Arranz A, Plack A, Basler M. Initiation of H1-T6SS dueling between Pseudomonas aeruginosa. mBio 2024; 15:e0035524. [PMID: 38990002 PMCID: PMC11323562 DOI: 10.1128/mbio.00355-24] [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: 02/03/2024] [Accepted: 06/10/2024] [Indexed: 07/12/2024] Open
Abstract
The Type VI secretion system (T6SS) is a multicomponent apparatus, present in many Gram-negative bacteria, which can inhibit bacterial prey in various ecological niches. Pseudomonas aeruginosa assembles one of its three T6SS (H1-T6SS) to respond to attacks from adjacent competing bacteria. Surprisingly, repeated assemblies of the H1-T6SS, termed dueling, were described in a monoculture in the absence of an attacker strain; however, the underlying mechanism was unknown. Here, we explored the role of H2-T6SS of P. aeruginosa in triggering H1-T6SS assembly. We show that H2-T6SS inactivation in P. aeruginosa causes a significant reduction in H1-T6SS dueling and that H2-T6SS activity directly triggers retaliation by the H1-T6SS. Intraspecific competition experiments revealed that elimination of H2-T6SS in non-immune prey cells conferred protection from H1-T6SS. Moreover, we show that the H1-T6SS response is triggered independently of the characterized lipase effectors of the H2-T6SS, as well as those of Acinetobacter baylyi and Vibrio cholerae. Our results suggest that H1-T6SS response to H2-T6SS in P. aeruginosa can impact intraspecific competition, particularly when the H1-T6SS effector-immunity pairs differ between strains, and could determine the outcome of multistrain colonization.IMPORTANCEThe opportunistic pathogen Pseudomonas aeruginosa harbors three different Type VI secretion systems (H1, H2, and H3-T6SS), which can translocate toxins that can inhibit bacterial competitors or inflict damage to eukaryotic host cells. Unlike the unregulated T6SS assembly in other Gram-negative bacteria, the H1-T6SS in P. aeruginosa is precisely assembled as a response to various cell damaging attacks from neighboring bacterial cells. Surprisingly, it was observed that neighboring P. aeruginosa cells repeatedly assemble their H1-T6SS toward each other. Mechanisms triggering this "dueling" behavior between sister cells were unknown. In this report, we used a combination of microscopy, genetic and intraspecific competition experiments to show that H2-T6SS initiates H1-T6SS dueling. Our study highlights the interplay between different T6SS clusters in P. aeruginosa, which may influence the outcomes of multistrain competition in various ecological settings such as biofilm formation and colonization of cystic fibrosis lungs.
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Affiliation(s)
- M. George
- Biozentrum, University of Basel, Basel, Switzerland
| | - S. Narayanan
- Biozentrum, University of Basel, Basel, Switzerland
| | | | - A. Plack
- Biozentrum, University of Basel, Basel, Switzerland
| | - M. Basler
- Biozentrum, University of Basel, Basel, Switzerland
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2
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Yu X, Yan Y, Zeng J, Liu Y, Sun X, Wang Z, Li L. T6SS nuclease effectors in Pseudomonas syringae act as potent antimicrobials in interbacterial competition. J Bacteriol 2024; 206:e0027323. [PMID: 38717111 PMCID: PMC11332151 DOI: 10.1128/jb.00273-23] [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: 08/16/2023] [Accepted: 04/09/2024] [Indexed: 06/21/2024] Open
Abstract
Type VI secretion system (T6SS) is a potent weapon employed by various Pseudomonas species to compete with neighboring microorganisms for limited nutrients and ecological niches. However, the involvement of T6SS effectors in interbacterial competition within the phytopathogen Pseudomonas syringae remains unknown. In this study, we examined two T6SS clusters in a wild-type P. syringae MB03 and verified the involvement of one cluster, namely, T6SS-1, in interbacterial competition. Additionally, our results showed that two T6SS DNase effectors, specifically Tde1 and Tde4, effectively outcompeted antagonistic bacteria, with Tde4 playing a prominent role. Furthermore, we found several cognate immunity proteins, including Tde1ia, Tde1ib, and Tde4i, which are located in the downstream loci of their corresponding effector protein genes and worked synergistically to protect MB03 cells from self-intoxication. Moreover, expression of either Tde1 or C-terminus of Tde4 in Escherichia coli cells induced DNA degradation and changes in cell morphology. Thus, our results provide new insights into the role of the T6SS effectors of P. syringae in the interbacterial competition in the natural environment. IMPORTANCE The phytopathogen Pseudomonas syringae employs an active type VI secretion system (T6SS) to outcompete other microorganisms in the natural environment, particularly during the epiphytic growth in the phyllosphere. By examining two T6SS clusters in P. syringae MB03, T6SS-1 is found to be effective in killing Escherichia coli cells. We highlight the excellent antibacterial effect of two T6SS DNase effectors, namely, Tde1 and Tde4. Both of them function as nuclease effectors, leading to DNA degradation and cell filamentation in prey cells, ultimately resulting in cell death. Our findings deepen our understanding of the T6SS effector repertoires used in P. syringae and will facilitate the development of effective antibacterial strategies.
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Affiliation(s)
- Xun Yu
- National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China
- Cooperative Innovation Center of Industrial Fermentation (Ministry of Education and Hubei Province), Hubei University of Technology, Wuhan, China
| | - Yubo Yan
- National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China
| | - Jie Zeng
- National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China
| | - Yongxuan Liu
- National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China
| | - Xiaowen Sun
- National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China
| | - Zhiyong Wang
- College of Biological and Food Engineering, Hubei Minzu University, Enshi, China
| | - Lin Li
- National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China
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3
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Chourashi R, Oglesby AG. Iron starvation increases the production of the Pseudomonas aeruginosa RsmY and RsmZ sRNAs in static conditions. J Bacteriol 2024; 206:e0027823. [PMID: 38624234 PMCID: PMC11112995 DOI: 10.1128/jb.00278-23] [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: 08/24/2023] [Accepted: 03/22/2024] [Indexed: 04/17/2024] Open
Abstract
Pseudomonas aeruginosa is an opportunistic Gram-negative pathogen that induces virulence gene expression in response to host-mediated iron starvation. Recently, our laboratory showed that some virulence factors are responsive to iron limitation in static but not shaking growth conditions. One of these is the HSI-2-type six secretion system (T6SS), which is also induced during chronic infection. Iron regulation of T6SS was partially impacted by the iron-responsive PrrF sRNA and completely dependent upon the Pseudomonas quinolone signal (PQS) biosynthetic gene pqsA. Here, we analyzed the impact of iron on the expression of two small regulatory RNAs (sRNAs), RsmY and RsmZ, that activate the expression of T6SS by sequestering the RsmA translation inhibitor. Our results demonstrate that iron starvation induces the expression of RsmY and RsmZ in static but not shaking cultures. We further show that this induction occurs through the rsmY and rsmZ promoters and is dependent upon PqsA. Disruption of either the pqsR gene also eliminated iron-dependent regulation of rsmY and rsmZ promoter activity. Taken together, our results show novel targets of iron regulation that are specific to static growth, highlighting the importance of studying regulatory mechanisms in static communities that may be more representative of growth during chronic infection.IMPORTANCEIron is a central component of various bacterial metabolic pathways making it an important host-acquired nutrient for pathogens to establish infection. Previous iron regulatory studies primarily relied on shaking bacterial cultures; while these ensure cultural homogeneity, they do not reflect growth conditions during infection. We recently showed that static growth of Pseudomonas aeruginosa promotes iron-dependent regulation of a type six secretion system (T6SS), a virulence factor that is induced during chronic infections. In the current study, we found that static growth also promotes iron-dependent regulation of the RsmY and RsmZ sRNAs, which are global regulators that affect T6SS during chronic P. aeruginosa lung infection. Hence, our work demonstrates the Rsm sRNAs as potential effectors of iron regulation during static growth that may also be relevant in chronic infection.
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Affiliation(s)
- Rhishita Chourashi
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, Maryland, USA
| | - Amanda G. Oglesby
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, Maryland, USA
- Department of Microbiology and Immunology, School of Medicine, University of Maryland, Baltimore, Maryland, USA
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4
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Fecht S, Paracuellos P, Subramoni S, Tan CAZ, Ilangovan A, Costa TRD, Filloux A. Functionality of chimeric TssA proteins in the type VI secretion system reveals sheath docking specificity within their N-terminal domains. Nat Commun 2024; 15:4283. [PMID: 38769318 PMCID: PMC11106082 DOI: 10.1038/s41467-024-48487-8] [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: 03/19/2023] [Accepted: 05/01/2024] [Indexed: 05/22/2024] Open
Abstract
The genome of Pseudomonas aeruginosa encodes three type VI secretion systems, each comprising a dozen distinct proteins, which deliver toxins upon T6SS sheath contraction. The least conserved T6SS component, TssA, has variations in size which influence domain organisation and structure. Here we show that the TssA Nt1 domain interacts directly with the sheath in a specific manner, while the C-terminus is essential for oligomerisation. We built chimeric TssA proteins by swapping C-termini and showed that these can be functional even when made of domains from different TssA sub-groups. Functional specificity requires the Nt1 domain, while the origin of the C-terminal domain is more permissive for T6SS function. We identify two regions in short TssA proteins, loop and hairpin, that contribute to sheath binding. We propose a docking mechanism of TssA proteins with the sheath, and a model for how sheath assembly is coordinated by TssA proteins from this position.
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Affiliation(s)
- Selina Fecht
- CBRB Centre for Bacterial Resistance Biology, Department of Life Sciences, Imperial College London, London, SW7 2AZ, UK
| | - Patricia Paracuellos
- CBRB Centre for Bacterial Resistance Biology, Department of Life Sciences, Imperial College London, London, SW7 2AZ, UK
| | - Sujatha Subramoni
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, 637551, Singapore
| | - Casandra Ai Zhu Tan
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, 637551, Singapore
| | - Aravindan Ilangovan
- School of Biological and Behavioural Sciences, Queen Mary University of London, London, E1 4NS, UK
| | - Tiago R D Costa
- CBRB Centre for Bacterial Resistance Biology, Department of Life Sciences, Imperial College London, London, SW7 2AZ, UK
| | - Alain Filloux
- CBRB Centre for Bacterial Resistance Biology, Department of Life Sciences, Imperial College London, London, SW7 2AZ, UK.
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, 637551, Singapore.
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5
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Cheng T, Cheang QW, Xu L, Sheng S, Li Z, Shi Y, Zhang H, Pang LM, Liu DX, Yang L, Liang ZX, Wang J. A PilZ domain protein interacts with the transcriptional regulator HinK to regulate type VI secretion system in Pseudomonas aeruginosa. J Biol Chem 2024; 300:105741. [PMID: 38340793 PMCID: PMC10912698 DOI: 10.1016/j.jbc.2024.105741] [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: 08/24/2023] [Revised: 01/29/2024] [Accepted: 02/04/2024] [Indexed: 02/12/2024] Open
Abstract
Type VI secretion systems (T6SS) are bacterial macromolecular complexes that secrete effectors into target cells or the extracellular environment, leading to the demise of adjacent cells and providing a survival advantage. Although studies have shown that the T6SS in Pseudomonas aeruginosa is regulated by the Quorum Sensing system and second messenger c-di-GMP, the underlying molecular mechanism remains largely unknown. In this study, we discovered that the c-di-GMP-binding adaptor protein PA0012 has a repressive effect on the expression of the T6SS HSI-I genes in P. aeruginosa PAO1. To probe the mechanism by which PA0012 (renamed TssZ, Type Six Secretion System -associated PilZ protein) regulates the expression of HSI-I genes, we conducted yeast two-hybrid screening and identified HinK, a LasR-type transcriptional regulator, as the binding partner of TssZ. The protein-protein interaction between HinK and TssZ was confirmed through co-immunoprecipitation assays. Further analysis suggested that the HinK-TssZ interaction was weakened at high c-di-GMP concentrations, contrary to the current paradigm wherein c-di-GMP enhances the interaction between PilZ proteins and their partners. Electrophoretic mobility shift assays revealed that the non-c-di-GMP-binding mutant TssZR5A/R9A interacts directly with HinK and prevents it from binding to the promoter of the quorum-sensing regulator pqsR. The functional connection between TssZ and HinK is further supported by observations that TssZ and HinK impact the swarming motility, pyocyanin production, and T6SS-mediated bacterial killing activity of P. aeruginosa in a PqsR-dependent manner. Together, these results unveil a novel regulatory mechanism wherein TssZ functions as an inhibitor that interacts with HinK to control gene expression.
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Affiliation(s)
- Tianfang Cheng
- Integrative Microbiology Research Centre, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, China
| | - Qing Wei Cheang
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Linghui Xu
- Integrative Microbiology Research Centre, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, China
| | - Shuo Sheng
- Integrative Microbiology Research Centre, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, China; Key Laboratory of Basic Pharmacology of the Ministry of Education, Joint International Research Laboratory of Ethnomedicine of the Ministry of Education and Key Laboratory of Basic Pharmacology of Guizhou Province, Zunyi Medical University, Zunyi, Guizhou, China
| | - Zhaoting Li
- Integrative Microbiology Research Centre, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, China
| | - Yu Shi
- Integrative Microbiology Research Centre, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, China
| | - Huiyan Zhang
- Integrative Microbiology Research Centre, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, China
| | - Li Mei Pang
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Ding Xiang Liu
- Integrative Microbiology Research Centre, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, China
| | - Liang Yang
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Zhao-Xun Liang
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore.
| | - Junxia Wang
- Integrative Microbiology Research Centre, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, China.
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6
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Kretsch RC, Andersen ES, Bujnicki JM, Chiu W, Das R, Luo B, Masquida B, McRae EK, Schroeder GM, Su Z, Wedekind JE, Xu L, Zhang K, Zheludev IN, Moult J, Kryshtafovych A. RNA target highlights in CASP15: Evaluation of predicted models by structure providers. Proteins 2023; 91:1600-1615. [PMID: 37466021 PMCID: PMC10792523 DOI: 10.1002/prot.26550] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 06/16/2023] [Accepted: 06/26/2023] [Indexed: 07/20/2023]
Abstract
The first RNA category of the Critical Assessment of Techniques for Structure Prediction competition was only made possible because of the scientists who provided experimental structures to challenge the predictors. In this article, these scientists offer a unique and valuable analysis of both the successes and areas for improvement in the predicted models. All 10 RNA-only targets yielded predictions topologically similar to experimentally determined structures. For one target, experimentalists were able to phase their x-ray diffraction data by molecular replacement, showing a potential application of structure predictions for RNA structural biologists. Recommended areas for improvement include: enhancing the accuracy in local interaction predictions and increased consideration of the experimental conditions such as multimerization, structure determination method, and time along folding pathways. The prediction of RNA-protein complexes remains the most significant challenge. Finally, given the intrinsic flexibility of many RNAs, we propose the consideration of ensemble models.
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Affiliation(s)
- Rachael C. Kretsch
- Biophysics Program, Stanford University School of Medicine, Stanford, CA, USA
| | - Ebbe S. Andersen
- Interdisciplinary Nanoscience Center and Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Janusz M. Bujnicki
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
| | - Wah Chiu
- Biophysics Program, Stanford University School of Medicine, Stanford, CA, USA
- Department of Bioengineering and James H. Clark Center, Stanford University, Stanford, CA, USA
- Division of CryoEM and Bioimaging, SSRL, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - Rhiju Das
- Biophysics Program, Stanford University School of Medicine, Stanford, CA, USA
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, USA
- Howard Hughes Medical Institute, Stanford, CA, USA
| | - Bingnan Luo
- The State Key Laboratory of Biotherapy, Frontiers Medical Center of Tianfu Jincheng Laboratory, Department of Geriatrics and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu 610044, Sichuan, China
| | - Benoît Masquida
- UMR 7156, CNRS – Universite de Strasbourg, Strasbourg, France
| | - Ewan K.S. McRae
- Center for RNA Therapeutics, Houston Methodist Research Institute, Houston, TX 77030, USA
| | - Griffin M. Schroeder
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, NY, 14642, USA
- Center for RNA Biology, University of Rochester School of Medicine and Dentistry, Rochester, NY, 14642, USA
| | - Zhaoming Su
- The State Key Laboratory of Biotherapy, Frontiers Medical Center of Tianfu Jincheng Laboratory, Department of Geriatrics and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu 610044, Sichuan, China
| | - Joseph E. Wedekind
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, NY, 14642, USA
- Center for RNA Biology, University of Rochester School of Medicine and Dentistry, Rochester, NY, 14642, USA
| | - Lily Xu
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA
| | - Kaiming Zhang
- Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China
| | - Ivan N. Zheludev
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, USA
| | - John Moult
- Department of Cell Biology and Molecular Genetics, Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, Maryland, USA
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7
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Durán D, Vazquez-Arias D, Blanco-Romero E, Garrido-Sanz D, Redondo-Nieto M, Rivilla R, Martín M. An Orphan VrgG Auxiliary Module Related to the Type VI Secretion Systems from Pseudomonas ogarae F113 Mediates Bacterial Killing. Genes (Basel) 2023; 14:1979. [PMID: 38002922 PMCID: PMC10671463 DOI: 10.3390/genes14111979] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 10/17/2023] [Accepted: 10/20/2023] [Indexed: 11/26/2023] Open
Abstract
The model rhizobacterium Pseudomonas ogarae F113, a relevant plant growth-promoting bacterium, encodes three different Type VI secretion systems (T6SS) in its genome. In silico analysis of its genome revealed the presence of a genetic auxiliary module containing a gene encoding an orphan VgrG protein (VgrG5a) that is not genetically linked to any T6SS structural cluster, but is associated with genes encoding putative T6SS-related proteins: a possible adaptor Tap protein, followed by a putative effector, Tfe8, and its putative cognate immunity protein, Tfi8. The bioinformatic analysis of the VgrG5a auxiliary module has revealed that this cluster is only present in several subgroups of the P. fluorescens complex of species. An analysis of the mutants affecting the vgrG5a and tfe8 genes has shown that the module is involved in bacterial killing. To test whether Tfe8/Tfi8 constitute an effector-immunity pair, the genes encoding Tfe8 and Tfi8 were cloned and expressed in E. coli, showing that the ectopic expression of tfe8 affected growth. The growth defect was suppressed by tfi8 ectopic expression. These results indicate that Tfe8 is a bacterial killing effector, while Tfi8 is its cognate immunity protein. The Tfe8 protein sequence presents homology to the proteins of the MATE family involved in drug extrusion. The Tfe8 effector is a membrane protein with 10 to 12 transmembrane domains that could destabilize the membranes of target cells by the formation of pores, revealing the importance of these effectors for bacterial interaction. Tfe8 represents a novel type of a T6SS effector present in pseudomonads.
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Affiliation(s)
- David Durán
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Darwin, 2, 28049 Madrid, Spain; (D.D.); (D.V.-A.); (E.B.-R.); (D.G.-S.); (M.R.-N.); (R.R.)
| | - David Vazquez-Arias
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Darwin, 2, 28049 Madrid, Spain; (D.D.); (D.V.-A.); (E.B.-R.); (D.G.-S.); (M.R.-N.); (R.R.)
| | - Esther Blanco-Romero
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Darwin, 2, 28049 Madrid, Spain; (D.D.); (D.V.-A.); (E.B.-R.); (D.G.-S.); (M.R.-N.); (R.R.)
| | - Daniel Garrido-Sanz
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Darwin, 2, 28049 Madrid, Spain; (D.D.); (D.V.-A.); (E.B.-R.); (D.G.-S.); (M.R.-N.); (R.R.)
- Department of Fundamental Microbiology, University of Lausanne, 1015 Lausanne, Switzerland
| | - Miguel Redondo-Nieto
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Darwin, 2, 28049 Madrid, Spain; (D.D.); (D.V.-A.); (E.B.-R.); (D.G.-S.); (M.R.-N.); (R.R.)
| | - Rafael Rivilla
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Darwin, 2, 28049 Madrid, Spain; (D.D.); (D.V.-A.); (E.B.-R.); (D.G.-S.); (M.R.-N.); (R.R.)
| | - Marta Martín
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Darwin, 2, 28049 Madrid, Spain; (D.D.); (D.V.-A.); (E.B.-R.); (D.G.-S.); (M.R.-N.); (R.R.)
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8
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Dupont CA, Bourigault Y, Osmond T, Nier M, Barbey C, Latour X, Konto-Ghiorghi Y, Verdon J, Merieau A. Pseudomonas fluorescens MFE01 uses 1-undecene as aerial communication molecule. Front Microbiol 2023; 14:1264801. [PMID: 37908545 PMCID: PMC10614000 DOI: 10.3389/fmicb.2023.1264801] [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: 07/21/2023] [Accepted: 09/27/2023] [Indexed: 11/02/2023] Open
Abstract
Bacterial communication is a fundamental process used to synchronize gene expression and collective behavior among the bacterial population. The most studied bacterial communication system is quorum sensing, a cell density system, in which the concentration of inductors increases to a threshold level allowing detection by specific receptors. As a result, bacteria can change their behavior in a coordinated way. While in Pseudomonas quorum sensing based on the synthesis of N-acyl homoserine lactone molecules is well studied, volatile organic compounds, although considered to be communication signals in the rhizosphere, are understudied. The Pseudomonas fluorescens MFE01 strain has a very active type six secretion system that can kill some competitive bacteria. Furthermore, MFE01 emits numerous volatile organic compounds, including 1-undecene, which contributes to the aerial inhibition of Legionella pneumophila growth. Finally, MFE01 appears to be deprived of N-acyl homoserine lactone synthase. The main objective of this study was to explore the role of 1-undecene in the communication of MFE01. We constructed a mutant affected in undA gene encoding the enzyme responsible for 1-undecene synthesis to provide further insight into the role of 1-undecene in MFE01. First, we studied the impacts of this mutation both on volatile organic compounds emission, using headspace solid-phase microextraction combined with gas chromatography-mass spectrometry and on L. pneumophila long-range inhibition. Then, we analyzed influence of 1-undecene on MFE01 coordinated phenotypes, including type six secretion system activity and biofilm formation. Next, to test the ability of MFE01 to synthesize N-acyl homoserine lactones in our conditions, we investigated in silico the presence of corresponding genes across the MFE01 genome and we exposed its biofilms to an N-acyl homoserine lactone-degrading enzyme. Finally, we examined the effects of 1-undecene emission on MFE01 biofilm maturation and aerial communication using an original experimental set-up. This study demonstrated that the ΔundA mutant is impaired in biofilm maturation. An exposure of the ΔundA mutant to the volatile compounds emitted by MFE01 during the biofilm development restored the biofilm maturation process. These findings indicate that P. fluorescens MFE01 uses 1-undecene emission for aerial communication, reporting for the first time this volatile organic compound as bacterial intraspecific communication signal.
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Affiliation(s)
- Charly A. Dupont
- Laboratoire de Communication Bactérienne et Stratégies Anti-infectieuses (CBSA UR), Univ Rouen Normandie, Université Caen Normandie, Normandie Univ, Rouen, France
- Structure Fédérative de Recherche Normandie Végétale and Entente Franco-Québécoise NOR-SEVE, NORVEGE, Rouen, France
| | - Yvann Bourigault
- Laboratoire de Communication Bactérienne et Stratégies Anti-infectieuses (CBSA UR), Univ Rouen Normandie, Université Caen Normandie, Normandie Univ, Rouen, France
- Structure Fédérative de Recherche Normandie Végétale and Entente Franco-Québécoise NOR-SEVE, NORVEGE, Rouen, France
| | - Théo Osmond
- Laboratoire de Communication Bactérienne et Stratégies Anti-infectieuses (CBSA UR), Univ Rouen Normandie, Université Caen Normandie, Normandie Univ, Rouen, France
- Structure Fédérative de Recherche Normandie Végétale and Entente Franco-Québécoise NOR-SEVE, NORVEGE, Rouen, France
| | - Maëva Nier
- Laboratoire Ecologie and Biologie des Interactions, Université de Poitiers, Poitiers, France
| | - Corinne Barbey
- Laboratoire de Communication Bactérienne et Stratégies Anti-infectieuses (CBSA UR), Univ Rouen Normandie, Université Caen Normandie, Normandie Univ, Rouen, France
- Structure Fédérative de Recherche Normandie Végétale and Entente Franco-Québécoise NOR-SEVE, NORVEGE, Rouen, France
| | - Xavier Latour
- Laboratoire de Communication Bactérienne et Stratégies Anti-infectieuses (CBSA UR), Univ Rouen Normandie, Université Caen Normandie, Normandie Univ, Rouen, France
- Structure Fédérative de Recherche Normandie Végétale and Entente Franco-Québécoise NOR-SEVE, NORVEGE, Rouen, France
| | - Yoan Konto-Ghiorghi
- Laboratoire de Communication Bactérienne et Stratégies Anti-infectieuses (CBSA UR), Univ Rouen Normandie, Université Caen Normandie, Normandie Univ, Rouen, France
- Structure Fédérative de Recherche Normandie Végétale and Entente Franco-Québécoise NOR-SEVE, NORVEGE, Rouen, France
| | - Julien Verdon
- Laboratoire Ecologie and Biologie des Interactions, Université de Poitiers, Poitiers, France
| | - Annabelle Merieau
- Laboratoire de Communication Bactérienne et Stratégies Anti-infectieuses (CBSA UR), Univ Rouen Normandie, Université Caen Normandie, Normandie Univ, Rouen, France
- Structure Fédérative de Recherche Normandie Végétale and Entente Franco-Québécoise NOR-SEVE, NORVEGE, Rouen, France
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9
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Hespanhol JT, Nóbrega-Silva L, Bayer-Santos E. Regulation of type VI secretion systems at the transcriptional, posttranscriptional and posttranslational level. MICROBIOLOGY (READING, ENGLAND) 2023; 169:001376. [PMID: 37552221 PMCID: PMC10482370 DOI: 10.1099/mic.0.001376] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Accepted: 07/25/2023] [Indexed: 08/09/2023]
Abstract
Bacteria live in complex polymicrobial communities and are constantly competing for resources. The type VI secretion system (T6SS) is a widespread antagonistic mechanism used by Gram-negative bacteria to gain an advantage over competitors. T6SSs translocate toxic effector proteins inside target prokaryotic cells in a contact-dependent manner. In addition, some T6SS effectors can be secreted extracellularly and contribute to the scavenging scarce metal ions. Bacteria deploy their T6SSs in different situations, categorizing these systems into offensive, defensive and exploitative. The great variety of bacterial species and environments occupied by such species reflect the complexity of regulatory signals and networks that control the expression and activation of the T6SSs. Such regulation is tightly controlled at the transcriptional, posttranscriptional and posttranslational level by abiotic (e.g. pH, iron) or biotic (e.g. quorum-sensing) cues. In this review, we provide an update on the current knowledge about the regulatory networks that modulate the expression and activity of T6SSs across several species, focusing on systems used for interbacterial competition.
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Affiliation(s)
- Julia Takuno Hespanhol
- Department of Microbiology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo 05508-900, Brazil
| | - Luize Nóbrega-Silva
- Department of Microbiology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo 05508-900, Brazil
| | - Ethel Bayer-Santos
- Department of Microbiology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo 05508-900, Brazil
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10
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Allsopp LP, Bernal P. Killing in the name of: T6SS structure and effector diversity. MICROBIOLOGY (READING, ENGLAND) 2023; 169:001367. [PMID: 37490402 PMCID: PMC10433429 DOI: 10.1099/mic.0.001367] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 07/12/2023] [Indexed: 07/27/2023]
Abstract
The life of bacteria is challenging, to endure bacteria employ a range of mechanisms to optimize their environment, including deploying the type VI secretion system (T6SS). Acting as a bacterial crossbow, this system delivers effectors responsible for subverting host cells, killing competitors and facilitating general secretion to access common goods. Due to its importance, this lethal machine has been evolutionarily maintained, disseminated and specialized to fulfil these vital functions. In fact, T6SS structural clusters are present in over 25 % of Gram-negative bacteria, varying in number from one to six different genetic clusters per organism. Since its discovery in 2006, research on the T6SS has rapidly progressed, yielding remarkable breakthroughs. The identification and characterization of novel components of the T6SS, combined with biochemical and structural studies, have revealed fascinating mechanisms governing its assembly, loading, firing and disassembly processes. Recent findings have also demonstrated the efficacy of this system against fungal and Gram-positive cells, expanding its scope. Ongoing research continues to uncover an extensive and expanding repertoire of T6SS effectors, the genuine mediators of T6SS function. These studies are shedding light on new aspects of the biology of prokaryotic and eukaryotic organisms. This review provides a comprehensive overview of the T6SS, highlighting recent discoveries of its structure and the diversity of its effectors. Additionally, it injects a personal perspective on avenues for future research, aiming to deepen our understanding of this combative system.
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Affiliation(s)
- Luke P. Allsopp
- National Heart and Lung Institute, Imperial College London, London, UK
| | - Patricia Bernal
- Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, Sevilla 41012, Spain
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11
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Zhao X, Xu C, Qu J, Jin Y, Bai F, Cheng Z, Wu W, Pan X. PitA Controls the H2- and H3-T6SSs through PhoB in Pseudomonas aeruginosa. Appl Environ Microbiol 2023; 89:e0209422. [PMID: 37184394 PMCID: PMC10304775 DOI: 10.1128/aem.02094-22] [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: 12/10/2022] [Accepted: 04/21/2023] [Indexed: 05/16/2023] Open
Abstract
Pseudomonas aeruginosa possesses three type VI secretion systems (T6SSs) that are involved in interspecies competition, internalization into epithelial cells, and virulence. Host-derived mucin glycans regulate the T6SSs through RetS, and attacks from other species activate the H1-T6SS. However, other environmental signals that control the T6SSs remain to be explored. Previously, we determined PitA to be a constitutive phosphate transporter, whose mutation reduces the intracellular phosphate concentration. Here, we demonstrate that mutation in the pitA gene increases the expression of the H2- and H3-T6SS genes and enhances bacterial uptake by A549 cells. We further found that mutation of pitA results in activation of the quorum sensing (QS) systems, which contributes to the upregulation of the H2- and H3-T6SS genes. Overexpression of the phosphate transporter complex genes pstSCAB or knockdown of the phosphate starvation response regulator gene phoB in the ΔpitA mutant reduces the expression of the QS genes and subsequently the H2- and H3-T6SS genes and bacterial internalization. Furthermore, growth of wild-type PA14 in a low-phosphate medium results in upregulation of the QS and H2- and H3-T6SS genes and bacterial internalization compared to those in cells grown in a high-phosphate medium. Deletion of the phoB gene abolished the differences in the expression of the QS and T6SS genes as well as bacterial internalization in the low- and high- phosphate media. Overall, our results elucidate the mechanism of PitA-mediated regulation on the QS system and H2- and H3-T6SSs and reveal a novel pathway that regulates the T6SSs in response to phosphate starvation. IMPORTANCE Pseudomonas aeruginosa is an opportunistic pathogenic bacterium that causes acute and chronic infections in humans. The type VI secretion systems (T6SSs) have been shown to associate with chronic infections. Understanding the mechanism used by the bacteria to sense environmental signals and regulate virulence factors will provide clues for developing novel effective treatment strategies. Here, we demonstrate a relationship between a phosphate transporter and the T6SSs and reveal a novel regulatory pathway that senses phosphate limitation and controls bacterial virulence factors in P. aeruginosa.
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Affiliation(s)
- Xinrui Zhao
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Congjuan Xu
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Junze Qu
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Yongxin Jin
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Fang Bai
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Zhihui Cheng
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Weihui Wu
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Xiaolei Pan
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
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12
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Rudzite M, Subramoni S, Endres RG, Filloux A. Effectiveness of Pseudomonas aeruginosa type VI secretion system relies on toxin potency and type IV pili-dependent interaction. PLoS Pathog 2023; 19:e1011428. [PMID: 37253075 PMCID: PMC10281587 DOI: 10.1371/journal.ppat.1011428] [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: 11/30/2022] [Revised: 06/20/2023] [Accepted: 05/17/2023] [Indexed: 06/01/2023] Open
Abstract
The type VI secretion system (T6SS) is an antibacterial weapon that is used by numerous Gram-negative bacteria to gain competitive advantage by injecting toxins into adjacent prey cells. Predicting the outcome of a T6SS-dependent competition is not only reliant on presence-absence of the system but instead involves a multiplicity of factors. Pseudomonas aeruginosa possesses 3 distinct T6SSs and a set of more than 20 toxic effectors with diverse functions including disruption of cell wall integrity, degradation of nucleic acids or metabolic impairment. We generated a comprehensive collection of mutants with various degrees of T6SS activity and/or sensitivity to each individual T6SS toxin. By imaging whole mixed bacterial macrocolonies, we then investigated how these P. aeruginosa strains gain a competitive edge in multiple attacker/prey combinations. We observed that the potency of single T6SS toxin varies significantly from one another as measured by monitoring the community structure, with some toxins acting better in synergy or requiring a higher payload. Remarkably the degree of intermixing between preys and attackers is also key to the competition outcome and is driven by the frequency of contact as well as the ability of the prey to move away from the attacker using type IV pili-dependent twitching motility. Finally, we implemented a computational model to better understand how changes in T6SS firing behaviours or cell-cell contacts lead to population level competitive advantages, thus providing conceptual insight applicable to all types of contact-based competition.
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Affiliation(s)
- Marta Rudzite
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Sujatha Subramoni
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore
| | - Robert G. Endres
- Centre for Integrative Systems Biology and Bioinformatics, Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Alain Filloux
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London, United Kingdom
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore
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13
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Blanco-Romero E, Durán D, Garrido-Sanz D, Redondo-Nieto M, Martín M, Rivilla R. Adaption of Pseudomonas ogarae F113 to the Rhizosphere Environment-The AmrZ-FleQ Hub. Microorganisms 2023; 11:microorganisms11041037. [PMID: 37110460 PMCID: PMC10146422 DOI: 10.3390/microorganisms11041037] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 04/10/2023] [Accepted: 04/13/2023] [Indexed: 04/29/2023] Open
Abstract
Motility and biofilm formation are two crucial traits in the process of rhizosphere colonization by pseudomonads. The regulation of both traits requires a complex signaling network that is coordinated by the AmrZ-FleQ hub. In this review, we describe the role of this hub in the adaption to the rhizosphere. The study of the direct regulon of AmrZ and the phenotypic analyses of an amrZ mutant in Pseudomonas ogarae F113 has shown that this protein plays a crucial role in the regulation of several cellular functions, including motility, biofilm formation, iron homeostasis, and bis-(3'-5')-cyclic dimeric guanosine monophosphate (c-di-GMP) turnover, controlling the synthesis of extracellular matrix components. On the other hand, FleQ is the master regulator of flagellar synthesis in P. ogarae F113 and other pseudomonads, but its implication in the regulation of multiple traits related with environmental adaption has been shown. Genomic scale studies (ChIP-Seq and RNA-Seq) have shown that in P. ogarae F113, AmrZ and FleQ are general transcription factors that regulate multiple traits. It has also been shown that there is a common regulon shared by the two transcription factors. Moreover, these studies have shown that AmrZ and FleQ form a regulatory hub that inversely regulate traits such as motility, extracellular matrix component production, and iron homeostasis. The messenger molecule c-di-GMP plays an essential role in this hub since its production is regulated by AmrZ and it is sensed by FleQ and required for its regulatory role. This regulatory hub is functional both in culture and in the rhizosphere, indicating that the AmrZ-FleQ hub is a main player of P. ogarae F113 adaption to the rhizosphere environment.
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Affiliation(s)
- Esther Blanco-Romero
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Darwin 2, 28049 Madrid, Spain
| | - David Durán
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Darwin 2, 28049 Madrid, Spain
| | - Daniel Garrido-Sanz
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Darwin 2, 28049 Madrid, Spain
- Department of Fundamental Microbiology, University of Lausanne, 1015 Lausanne, Switzerland
| | - Miguel Redondo-Nieto
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Darwin 2, 28049 Madrid, Spain
| | - Marta Martín
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Darwin 2, 28049 Madrid, Spain
| | - Rafael Rivilla
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Darwin 2, 28049 Madrid, Spain
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14
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Singh RP, Kumari K. Bacterial type VI secretion system (T6SS): an evolved molecular weapon with diverse functionality. Biotechnol Lett 2023; 45:309-331. [PMID: 36683130 DOI: 10.1007/s10529-023-03354-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 12/14/2022] [Accepted: 01/05/2023] [Indexed: 01/24/2023]
Abstract
Bacterial secretion systems are nanomolecular complexes that release a diverse set of virulence factors/or proteins into its surrounding or translocate to their target host cells. Among these systems, type VI secretion system 'T6SS' is a recently discovered molecular secretion system which is widely distributed in Gram-negative (-ve) bacteria, and shares structural similarity with the puncturing device of bacteriophages. The presence of T6SS is an advantage to many bacteria as it delivers toxins to its neighbour pathogens for competitive survival, and also translocates protein effectors to the host cells, leading to disruption of lipid membranes, cell walls, and cytoskeletons etc. Recent studies have characterized both anti-prokaryotic and anti-eukaryotic effectors, where T6SS is involved in diverse cellular functions including favouring colonization, enhancing the survival, adhesive modifications, internalization, and evasion of the immune system. With the evolution of advanced genomics and proteomics tools, there has been an increase in the number of characterized T6SS effector arsenals and also more clear information about the adaptive significance of this complex system. The functions of T6SS are generally regulated at the transcription, post-transcription and post-translational levels through diverse mechanisms. In the present review, we aimed to provide information about the distribution of T6SS in diverse bacteria, any structural similarity/or dissimilarity, effectors proteins, functional significance, and regulatory mechanisms. We also tried to provide information about the diverse roles played by T6SS in its natural environments and hosts, and further any changes in the microbiome.
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Affiliation(s)
- Rajnish Prakash Singh
- Department of Bioengineering and Biotechnology, Birla Institute of Technology, Mesra, Ranchi, Jharkhand, 835215, India.
| | - Kiran Kumari
- Department of Bioengineering and Biotechnology, Birla Institute of Technology, Mesra, Ranchi, Jharkhand, 835215, India
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15
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Zhang J, Guan J, Wang M, Li G, Djordjevic M, Tai C, Wang H, Deng Z, Chen Z, Ou HY. SecReT6 update: a comprehensive resource of bacterial Type VI Secretion Systems. SCIENCE CHINA. LIFE SCIENCES 2023; 66:626-634. [PMID: 36346548 DOI: 10.1007/s11427-022-2172-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Accepted: 07/27/2022] [Indexed: 11/10/2022]
Abstract
Type VI Secretion System (T6SS) plays significant roles in microbial activities via injecting effectors into adjacent cells or environments. T6SS increasingly gained attention due to its important influence on pathogenesis, microbial competition, etc. T6SS-associated research is explosively expanding on numerous grounds that call for an efficient resource. The SecReT6 version 3 provides comprehensive information on T6SS and the interactions between T6SS and T6SS-related proteins such as T6SS regulators and T6SS effectors. To assist T6SS researches like microbial competition and regulatory mechanisms, SecReT6 v3 developed online tools for detection and analysis of T6SS and T6SS-related proteins and estimation of T6SS-dependent killing risk. We have identified a novel T6SS regulator and T6SS-dependent killing capacity in Acinetobacter baumannii clinical isolates with the aid of SecReT6 v3. 17,212 T6SSs and plentiful T6SS-related proteins in 26,573 bacterial complete genomes were also detected, analyzed and incorporated into the database. The database is freely available at https://bioinfo-mml.sjtu.edu.cn/SecReT6/ .
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Affiliation(s)
- Jianfeng Zhang
- State Key Laboratory of Microbial Metabolism, Shanghai-Islamabad-Belgrade Joint Innovation Center on Antibacterial Resistances, Joint International Laboratory on Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
- Intensive Care Unit, First Affiliated Hospital of Guangxi Medical University, Nanning, 530021, China
| | - Jiahao Guan
- State Key Laboratory of Microbial Metabolism, Shanghai-Islamabad-Belgrade Joint Innovation Center on Antibacterial Resistances, Joint International Laboratory on Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Meng Wang
- State Key Laboratory of Microbial Metabolism, Shanghai-Islamabad-Belgrade Joint Innovation Center on Antibacterial Resistances, Joint International Laboratory on Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Gang Li
- Department of Laboratory Medicine, Jinshan Hospital, Shanghai Medical College, Fudan University, Shanghai, 201500, China
| | - Marko Djordjevic
- Quantitative Biology Group, Institute of Physiology and Biochemistry, Faculty of Biology, University of Belgrade, Belgrade, 11000, Serbia
| | - Cui Tai
- State Key Laboratory of Microbial Metabolism, Shanghai-Islamabad-Belgrade Joint Innovation Center on Antibacterial Resistances, Joint International Laboratory on Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Hui Wang
- State Key Laboratory of Pathogens and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, 100071, China
| | - Zixin Deng
- State Key Laboratory of Microbial Metabolism, Shanghai-Islamabad-Belgrade Joint Innovation Center on Antibacterial Resistances, Joint International Laboratory on Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Zhaoyan Chen
- Intensive Care Unit, First Affiliated Hospital of Guangxi Medical University, Nanning, 530021, China.
| | - Hong-Yu Ou
- State Key Laboratory of Microbial Metabolism, Shanghai-Islamabad-Belgrade Joint Innovation Center on Antibacterial Resistances, Joint International Laboratory on Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China.
- Shanghai Key Laboratory of Veterinary Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China.
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16
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Li M, Guo N, Song G, Huang Y, Wang L, Zhang Y, Wang T. Type II Toxin-Antitoxin Systems in Pseudomonas aeruginosa. Toxins (Basel) 2023; 15:164. [PMID: 36828478 PMCID: PMC9966142 DOI: 10.3390/toxins15020164] [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: 01/04/2023] [Revised: 02/03/2023] [Accepted: 02/14/2023] [Indexed: 02/22/2023] Open
Abstract
Toxin-antitoxin (TA) systems are typically composed of a stable toxin and a labile antitoxin; the latter counteracts the toxicity of the former under suitable conditions. TA systems are classified into eight types based on the nature and molecular modes of action of the antitoxin component so far. The 10 pairs of TA systems discovered and experimentally characterised in Pseudomonas aeruginosa are type II TA systems. Type II TA systems have various physiological functions, such as virulence and biofilm formation, protection host against antibiotics, persistence, plasmid maintenance, and prophage production. Here, we review the type II TA systems of P. aeruginosa, focusing on their biological functions and regulatory mechanisms, providing potential applications for the novel drug design.
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Affiliation(s)
| | | | | | | | | | - Yani Zhang
- Provincial Key Laboratory of Biotechnology, Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi’an 710069, China
| | - Tietao Wang
- Provincial Key Laboratory of Biotechnology, Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi’an 710069, China
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17
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Colautti J, Bullen NP, Whitney JC. Lack of evidence that Pseudomonas aeruginosa AmpDh3-PA0808 constitute a type VI secretion system effector-immunity pair. Mol Microbiol 2023; 119:262-274. [PMID: 36577706 DOI: 10.1111/mmi.15021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 12/19/2022] [Accepted: 12/20/2022] [Indexed: 12/29/2022]
Abstract
Type VI secretion systems (T6SSs) are cell envelope-spanning protein complexes that Gram-negative bacteria use to inject a diverse arsenal of antibacterial toxins into competitor cells. Recently, Wang et al. reported that the H2-T6SS of Pseudomonas aeruginosa delivers the peptidoglycan recycling amidase, AmpDh3, into the periplasm of recipient cells where it is proposed to act as a peptidoglycan degrading toxin. They further reported that PA0808, the open reading frame downstream of AmpDh3, encodes an immunity protein that localizes to the periplasm where it binds to and inactivates intercellularly delivered AmpDh3, thus protecting against its toxic activity. Given that AmpDh3 has an established role in cell wall homeostasis and that no precedent exists for cytosolic enzymes moonlighting as T6SS effectors, we attempted to replicate these findings. We found that cells lacking PA0808 are not susceptible to bacterial killing by AmpDh3 and that PA0808 and AmpDh3 do not physically interact in vitro or in vivo. Additionally, we found no evidence that AmpDh3 is exported from cells, including by strains with a constitutively active H2-T6SS. Finally, subcellular fractionation experiments and a 1.97 Å crystal structure reveal that PA0808 does not contain a canonical signal peptide or localize to the correct cellular compartment to confer protection against a cell wall targeting toxin. Taken together, these results cast doubt on the assertion that AmpDh3-PA0808 constitutes an H2-T6SS effector-immunity pair.
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Affiliation(s)
- Jake Colautti
- Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario, Canada.,Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
| | - Nathan P Bullen
- Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario, Canada.,Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
| | - John C Whitney
- Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario, Canada.,Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada.,David Braley Center for Antibiotic Discovery, McMaster University, Hamilton, Ontario, Canada
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18
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Wang GZ, Warren EA, Haas AL, Peña AS, Kiedrowski MR, Lomenick B, Chou TF, Bomberger JM, Tirrell DA, Limoli DH. Staphylococcal secreted cytotoxins are competition sensing signals for Pseudomonas aeruginosa. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.29.526047. [PMID: 36747623 PMCID: PMC9900984 DOI: 10.1101/2023.01.29.526047] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Coinfection with two notorious opportunistic pathogens, the Gram-negative Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus , dominates chronic pulmonary infections. While coinfection is associated with poor patient outcomes, the interspecies interactions responsible for such decline remain unknown. Here, we dissected molecular mechanisms of interspecies sensing between P. aeruginosa and S. aureus . We discovered that P. aeruginosa senses S. aureus secreted peptides and, counterintuitively, moves towards these toxins. P. aeruginosa tolerates such a strategy through "competition sensing", whereby it preempts imminent danger/competition by arming cells with type six secretion (T6S) and iron acquisition systems. Intriguingly, while T6S is predominantly described as weaponry targeting Gram-negative and eukaryotic cells, we find that T6S is essential for full P. aeruginosa competition with S. aureus , a previously undescribed role for T6S. Importantly, competition sensing was activated during coinfection of bronchial epithelia, including T6S islands targeting human cells. This study reveals critical insight into both interspecies competition and how antagonism may cause collateral damage to the host environment.
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19
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Robinson LA, Collins ACZ, Murphy RA, Davies JC, Allsopp LP. Diversity and prevalence of type VI secretion system effectors in clinical Pseudomonas aeruginosa isolates. Front Microbiol 2023; 13:1042505. [PMID: 36687572 PMCID: PMC9846239 DOI: 10.3389/fmicb.2022.1042505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Accepted: 11/23/2022] [Indexed: 01/06/2023] Open
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen and a major driver of morbidity and mortality in people with Cystic Fibrosis (CF). The Type VI secretion system (T6SS) is a molecular nanomachine that translocates effectors across the bacterial membrane into target cells or the extracellular environment enabling intermicrobial interaction. P. aeruginosa encodes three T6SS clusters, the H1-, H2- and H3-T6SS, and numerous orphan islands. Genetic diversity of T6SS-associated effectors in P. aeruginosa has been noted in reference strains but has yet to be explored in clinical isolates. Here, we perform a comprehensive bioinformatic analysis of the pangenome and T6SS effector genes in 52 high-quality clinical P. aeruginosa genomes isolated from CF patients and housed in the Personalised Approach to P. aeruginosa strain repository. We confirm that the clinical CF isolate pangenome is open and principally made up of accessory and unique genes that may provide strain-specific advantages. We observed genetic variability in some effector/immunity encoding genes and show that several well-characterised vgrG and PAAR islands are absent from numerous isolates. Our analysis shows clear evidence of disruption to T6SS genomic loci through transposon, prophage, and mobile genetic element insertions. We identified an orphan vgrG island in P. aeruginosa strain PAK and five clinical isolates using in silico analysis which we denote vgrG7, predicting a gene within this cluster to encode a Tle2 lipase family effector. Close comparison of T6SS loci in clinical isolates compared to reference P. aeruginosa strain PAO1 revealed the presence of genes encoding eight new T6SS effectors with the following putative functions: cytidine deaminase, lipase, metallopeptidase, NADase, and pyocin. Finally, the prevalence of characterised and putative T6SS effectors were assessed in 532 publicly available P. aeruginosa genomes, which suggests the existence of accessory effectors. Our in silico study of the P. aeruginosa T6SS exposes a level of genetic diversity at T6SS genomic loci not seen to date within P. aeruginosa, particularly in CF isolates. As understanding the effector repertoire is key to identifying the targets of T6SSs and its efficacy, this comprehensive analysis provides a path for future experimental characterisation of these mediators of intermicrobial competition and host manipulation.
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Affiliation(s)
- Luca A. Robinson
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Alice C. Z. Collins
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Ronan A. Murphy
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Jane C. Davies
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
- Department of Paediatric Respiratory Medicine, Royal Brompton Hospital, London, United Kingdom
| | - Luke P. Allsopp
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
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20
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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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21
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Yang Y, Pan D, Tang Y, Li J, Zhu K, Yu Z, Zhu L, Wang Y, Chen P, Li C. H3-T6SS of Pseudomonas aeruginosa PA14 contributes to environmental adaptation via secretion of a biofilm-promoting effector. STRESS BIOLOGY 2022; 2:55. [PMID: 37676573 PMCID: PMC10442045 DOI: 10.1007/s44154-022-00078-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Accepted: 12/11/2022] [Indexed: 09/08/2023]
Abstract
Microbial species often occur in complex communities and exhibit intricate synergistic and antagonistic interactions. To avoid predation and compete for favorable niches, bacteria have evolved specialized protein secretion systems. The type VI secretion system (T6SS) is a versatile secretion system widely distributed among Gram-negative bacteria that translocates effectors into target cells or the extracellular milieu via various physiological processes. Pseudomonas aeruginosa is an opportunistic pathogen responsible for many diseases, and it has three independent T6SSs (H1-, H2-, and H3-T6SS). In this study, we found that the H3-T6SS of highly virulent P. aeruginosa PA14 is negatively regulated by OxyR and OmpR, which are global regulatory proteins of bacterial oxidative and acid stress. In addition, we identified a H3-T6SS effector PA14_33970, which is located upstream of VgrG3. PA14_33970 interacted directly with VgrG3 and translocated into host cells. Moreover, we found that H3-T6SS and PA14_33970 play crucial roles in oxidative, acid, and osmotic stress resistance, as well as in motility and biofilm formation. PA14_33970 was identified as a new T6SS effector promoting biofilm formation and thus named TepB. Furthermore, we found that TepB contributes to the virulence of P. aeruginosa PA14 toward Caenorhabditis elegans. Overall, our study indicates that H3-T6SS and its biofilm-promoting effector TepB are regulated by OxyR and OmpR, both of which are important for adaptation of P. aeruginosa PA14 to multiple stressors, providing insights into the regulatory mechanisms and roles of T6SSs in P. aeruginosa.
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Affiliation(s)
- Yantao Yang
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Damin Pan
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Yanan Tang
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Jiali Li
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Kaixiang Zhu
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Zonglan Yu
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Lingfang Zhu
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Yao Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Peng Chen
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, China.
| | - Changfu Li
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, China.
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22
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An Important Role of the Type VI Secretion System of Pseudomonas aeruginosa Regulated by Dnr in Response to Anaerobic Environments. Microbiol Spectr 2022; 10:e0153322. [PMID: 36301114 PMCID: PMC9769707 DOI: 10.1128/spectrum.01533-22] [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] [Indexed: 01/05/2023] Open
Abstract
The type VI secretion system (T6SS) is capable of secreting a variety of metal-binding proteins involved in metal ion uptake, and it mediates an active metal ion transport system that contributes to competition between bacteria. Pseudomonas aeruginosa H2-T6SS can increase molybdenum ion acquisition and enhance bacterial survival advantage by promoting the secretion of the molybdate-binding protein ModA, in which the expression of H2-T6SS core genes hcp2, hsiA2, and clpV2 is activated by anaerobic conditions and are all regulated by the global regulator Anr. Here, we report the regulation of T6SS by Dnr, a dedicated dissimilatory nitrate respiration regulator in P. aeruginosa. Of the three distinct T6SS loci carried by P. aeruginosa, only the anaerobic expression of H2-T6SS was activated by Dnr; H1-T6SS or H3-T6SS did not respond to anaerobically induced activation. We also demonstrated that Dnr promotes the anaerobic secretion of ModA, which acts as a potential substrate for H2-T6SS, providing an advantage not only for the anaerobic growth of bacteria but also for functional competition. Overall, this study elucidates the important role played by Dnr in mediating the anaerobic expression of T6SS in P. aeruginosa, indicating that the functional advantage of H2-T6SS in response to anaerobic induction may be a conditional environmental adaptation. It also extends our understanding of the function of Dnr as a specific regulator of dissimilatory nitrate respiration. IMPORTANCE The type VI secretion system (T6SS) plays an important role in bacterial competition by mediating the transport of active metal ions. Pseudomonas aeruginosa carries three distinct T6SS loci (H1-, H2-, and H3-T6SS). The H2-T6SS promotes the secretion of the molybdate-binding protein ModA for the acquisition of molybdenum ions to adapt to anaerobic survival. Here, we report that the specialized dissimilatory nitrate respiration regulator Dnr in P. aeruginosa controls the anaerobic expression of H2-T6SS and that this regulation is essential for ModA protein secretion, anaerobic growth, and bacterial competition. This study elucidates the regulatory mechanism of Dnr on H2-T6SS in P. aeruginosa, revealing an important role played by H2-T6SS in adapting to an anaerobic environment.
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23
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Virulence Induction in Pseudomonas aeruginosa under Inorganic Phosphate Limitation: a Proteomics Perspective. Microbiol Spectr 2022; 10:e0259022. [PMID: 36354317 PMCID: PMC9769906 DOI: 10.1128/spectrum.02590-22] [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] [Indexed: 11/12/2022] Open
Abstract
Inorganic phosphate (Pi) is a central nutrient and signal molecule for bacteria. Pi limitation was shown to increase the virulence of several phylogenetically diverse pathogenic bacteria with different lifestyles. Hypophosphatemia enhances the risk of death in patients due to general bacteremia and was observed after surgical injury in humans. Phosphate therapy, or the reduction of bacterial virulence by the administration of Pi or phosphate-containing compounds, is a promising anti-infective therapy approach that will not cause cytotoxicity or the emergence of antibiotic-resistant strains. The proof of concept of phosphate therapy has been obtained using primarily Pseudomonas aeruginosa (PA). However, a detailed understanding of Pi-induced changes at protein levels is missing. Using pyocyanin production as proxy, we show that the Pi-mediated induction of virulence is a highly cooperative process that occurs between 0.2 to 0.6 mM Pi. We present a proteomics study of PA grown in minimal medium supplemented with either 0.2 mM or 1 mM Pi and rich medium. About half of the predicted PA proteins could be quantified. Among the 1,471 dysregulated proteins comparing growth in 0.2 mM to 1 mM Pi, 1,100 were depleted under Pi-deficient conditions. Most of these proteins are involved in general and energy metabolism, different biosynthetic and catabolic routes, or transport. Pi depletion caused accumulation of proteins that belong to all major families of virulence factors, including pyocyanin synthesis, secretion systems, quorum sensing, chemosensory signaling, and the secretion of proteases, phospholipases, and phosphatases, which correlated with an increase in exoenzyme production and antibacterial activity. IMPORTANCE Antibiotics are our main weapons to fight pathogenic bacteria, but the increase in antibiotic-resistant strains and their consequences represents a major global health challenge, revealing the necessity to develop alternative antimicrobial strategies that do not involve the bacterial killing or growth inhibition. P. aeruginosa has been placed second on the global priority list to guide research on the development of new antibiotics. One of the most promising alternative strategies is the phosphate therapy for which the proof of concept has been obtained for P. aeruginosa. This article reports the detailed changes at the protein levels comparing P. aeruginosa grown under Pi-abundant and Pi-depleted conditions. These data describe in detail the molecular mechanisms underlying phosphate therapy. Apart from Pi, several other phosphate-containing compounds have been used for phosphate therapy and this study will serve as a reference for comparative studies aimed at evaluating the effect of alternative compounds.
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24
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An ADP-ribosyltransferase toxin kills bacterial cells by modifying structured non-coding RNAs. Mol Cell 2022; 82:3484-3498.e11. [PMID: 36070765 DOI: 10.1016/j.molcel.2022.08.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 07/25/2022] [Accepted: 08/11/2022] [Indexed: 11/24/2022]
Abstract
ADP-ribosyltransferases (ARTs) were among the first identified bacterial virulence factors. Canonical ART toxins are delivered into host cells where they modify essential proteins, thereby inactivating cellular processes and promoting pathogenesis. Our understanding of ARTs has since expanded beyond protein-targeting toxins to include antibiotic inactivation and DNA damage repair. Here, we report the discovery of RhsP2 as an ART toxin delivered between competing bacteria by a type VI secretion system of Pseudomonas aeruginosa. A structure of RhsP2 reveals that it resembles protein-targeting ARTs such as diphtheria toxin. Remarkably, however, RhsP2 ADP-ribosylates 2'-hydroxyl groups of double-stranded RNA, and thus, its activity is highly promiscuous with identified cellular targets including the tRNA pool and the RNA-processing ribozyme, ribonuclease P. Consequently, cell death arises from the inhibition of translation and disruption of tRNA processing. Overall, our data demonstrate a previously undescribed mechanism of bacterial antagonism and uncover an unprecedented activity catalyzed by ART enzymes.
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25
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Kim SK, Lee JB, Yoon JW. Characterization of transcriptional activities at a divergent promoter of the type VI secretion system in enterohemorrhagic Escherichia coli O157:H7. J Microbiol 2022; 60:928-934. [DOI: 10.1007/s12275-022-2109-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 05/16/2022] [Accepted: 05/30/2022] [Indexed: 10/15/2022]
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26
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Dubern JF, Romero M, Mai-Prochnow A, Messina M, Trampari E, Gijzel HNV, Chan KG, Carabelli AM, Barraud N, Lazenby J, Chen Y, Robertson S, Malone JG, Williams P, Heeb S, Cámara M. ToxR is a c-di-GMP binding protein that modulates surface-associated behaviour in Pseudomonas aeruginosa. NPJ Biofilms Microbiomes 2022; 8:64. [PMID: 35982053 PMCID: PMC9388670 DOI: 10.1038/s41522-022-00325-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 07/26/2022] [Indexed: 11/09/2022] Open
Abstract
Pseudomonas aeruginosa uses multiple protein regulators that work in tandem to control the production of a wide range of virulence factors and facilitate rapid adaptation to diverse environmental conditions. In this opportunistic pathogen, ToxR was known to positively regulate the production of the major virulence factor exotoxin A and now, through analysis of genetic changes between two sublines of P. aeruginosa PAO1 and functional complementation of swarming, we have identified a previously unknown role of ToxR in surface-associated motility in P. aeruginosa. Further analysis revealed that ToxR had an impact on swarming motility by regulating the Rhl quorum sensing system and subsequent production of rhamnolipid surfactants. Additionally, ToxR was found to tightly bind cyclic diguanylate (c-di-GMP) and negatively affect traits controlled by this second messenger including reducing biofilm formation and the expression of Psl and Pel exopolysaccharides, necessary for attachment and sessile communities matrix scaffolding, in P. aeruginosa. Moreover, a link between the post-transcriptional regulator RsmA and toxR expression via the alternative sigma factor PvdS, induced under iron-limiting conditions, is established. This study reveals the importance of ToxR in a sophisticated regulation of free-living and biofilm-associated lifestyles, appropriate for establishing acute or chronic P. aeruginosa infections.
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Affiliation(s)
- Jean-Frédéric Dubern
- National Biofilms Innovation Centre, Biodiscovery Institute and School of Life Sciences, University of Nottingham, Nottingham, UK
| | - Manuel Romero
- National Biofilms Innovation Centre, Biodiscovery Institute and School of Life Sciences, University of Nottingham, Nottingham, UK
| | - Anne Mai-Prochnow
- National Biofilms Innovation Centre, Biodiscovery Institute and School of Life Sciences, University of Nottingham, Nottingham, UK
- School of Chemical and Biomolecular Engineering, University of Sydney, Sydney, Australia
| | - Marco Messina
- National Biofilms Innovation Centre, Biodiscovery Institute and School of Life Sciences, University of Nottingham, Nottingham, UK
- Department of Science, University Roma Tre, Rome, Italy
| | - Eleftheria Trampari
- Department of Molecular Microbiology, John Innes Centre, Norwich, UK
- Quadram Institute Bioscience, Norwich Research Park, Norwich, UK
| | - Hardeep Naghra-van Gijzel
- National Biofilms Innovation Centre, Biodiscovery Institute and School of Life Sciences, University of Nottingham, Nottingham, UK
- Genomic Sciences, GlaxoSmithKline Research and Development, Stevenage, UK
| | - Kok-Gan Chan
- Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia
- International Genome Centre, Jiangsu University, Zhenjiang, China
| | - Alessandro M Carabelli
- School of Pharmacy, Boots Science Building, University of Nottingham, Nottingham, UK
- Department of Medicine, University of Cambridge, Cambridge, UK
| | - Nicolas Barraud
- Centre for Marine Bio-Innovation, School of Biotechnology and Biomolecular Science, University of New South Wales, Sydney, Australia
- Genetics of Biofilms Unit, Institut Pasteur, Paris, France
| | - James Lazenby
- National Biofilms Innovation Centre, Biodiscovery Institute and School of Life Sciences, University of Nottingham, Nottingham, UK
- Quadram Institute Bioscience, Norwich Research Park, Norwich, UK
| | - Ye Chen
- National Biofilms Innovation Centre, Biodiscovery Institute and School of Life Sciences, University of Nottingham, Nottingham, UK
- Q Squared Solutions, Crystal Plaza, Pudong, Shanghai, China
| | - Shaun Robertson
- National Biofilms Innovation Centre, Biodiscovery Institute and School of Life Sciences, University of Nottingham, Nottingham, UK
| | - Jacob G Malone
- Department of Molecular Microbiology, John Innes Centre, Norwich, UK
- School of Biological Sciences, University of East Anglia, Norwich, UK
| | - Paul Williams
- National Biofilms Innovation Centre, Biodiscovery Institute and School of Life Sciences, University of Nottingham, Nottingham, UK
| | - Stephan Heeb
- National Biofilms Innovation Centre, Biodiscovery Institute and School of Life Sciences, University of Nottingham, Nottingham, UK
| | - Miguel Cámara
- National Biofilms Innovation Centre, Biodiscovery Institute and School of Life Sciences, University of Nottingham, Nottingham, UK.
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27
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Liu P, Yue C, Liu L, Gao C, Lyu Y, Deng S, Tian H, Jia X. The function of small RNA in Pseudomonas aeruginosa. PeerJ 2022; 10:e13738. [PMID: 35891650 PMCID: PMC9308961 DOI: 10.7717/peerj.13738] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Accepted: 06/25/2022] [Indexed: 01/17/2023] Open
Abstract
Pseudomonas aeruginosa, the main conditional pathogen causing nosocomial infection, is a gram-negative bacterium with the largest genome among the known bacteria. The main reasons why Pseudomonas aeruginosa is prone to drug-resistant strains in clinic are: the drug-resistant genes in its genome and the drug resistance easily induced by single antibiotic treatment. With the development of high-throughput sequencing technology and bioinformatics, the functions of various small RNAs (sRNA) in Pseudomonas aeruginosa are being revealed. Different sRNAs regulate gene expression by binding to protein or mRNA to play an important role in the complex regulatory network. In this article, first, the importance and biological functions of different sRNAs in Pseudomonas aeruginosa are explored, and then the evidence and possibilities that sRNAs served as drug therapeutic targets are discussed, which may introduce new directions to develop novel disease treatment strategies.
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Affiliation(s)
- Pei Liu
- Yan’an University, Key Laboratory of Microbial Drugs Innovation and Transformation, Yan’an, Shaanxi, China
| | - Changwu Yue
- Yan’an University, Key Laboratory of Microbial Drugs Innovation and Transformation, Yan’an, Shaanxi, China
| | - Lihua Liu
- Chengdu Medical College, Non-coding RNA and Drug Discovery Key Laboratory of Sichuan Province, Chengdu, Sichuan, China
| | - Can Gao
- Yan’an University, Key Laboratory of Microbial Drugs Innovation and Transformation, Yan’an, Shaanxi, China
| | - Yuhong Lyu
- Yan’an University, Key Laboratory of Microbial Drugs Innovation and Transformation, Yan’an, Shaanxi, China
| | - Shanshan Deng
- Chengdu Medical College, Non-coding RNA and Drug Discovery Key Laboratory of Sichuan Province, Chengdu, Sichuan, China
| | - Hongying Tian
- Yan’an University, Key Laboratory of Microbial Drugs Innovation and Transformation, Yan’an, Shaanxi, China
| | - Xu Jia
- Chengdu Medical College, Non-coding RNA and Drug Discovery Key Laboratory of Sichuan Province, Chengdu, Sichuan, China,School of Basic Medical Science, Chengdu Medical College, Chengdu, Sichuan, China
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28
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Antimicrobial peptide S100A12 (calgranulin C) inhibits growth, biofilm formation, pyoverdine secretion and suppresses type VI secretion system in Pseudomonas aeruginosa. Microb Pathog 2022; 169:105654. [PMID: 35753599 DOI: 10.1016/j.micpath.2022.105654] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Revised: 06/17/2022] [Accepted: 06/20/2022] [Indexed: 12/13/2022]
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen and is the major cause of corneal infections in India and worldwide. The increase in antimicrobial resistance among Pseudomonas has prompted rise in significant research to develop alternative therapeutics. Antimicrobial peptides (AMPs) are considered as potent alternatives to combat bacterial infections. In this study, we investigated the role of S100A12, a host defense peptide, against PAO1 and an ocular clinical isolate. Increased expression of S100A12 was observed in corneal tissues obtained from Pseudomonas keratitis patients by immunohistochemistry. S100A12 significantly inhibited growth of Pseudomonas in vitro as determined from colony forming units. Furthermore, recombinant S100A12 reduced the corneal opacity and the bacterial load in a mouse model of Pseudomonas keratitis. Transcriptome changes in PAO1 in response to S100A12 was investigated using RNA sequencing. The pathway analysis of transcriptome data revealed that S100A12 inhibits expression of genes involved in pyoverdine synthesis and biofilm formation. It also impedes several important pathways like redox, pyocyanin synthesis and type 6 secretion system (T6SS). The transcriptome data was further validated by checking the expression of several affected genes by quantitative PCR. Our study sheds light on how S100A12 impacts Pseudomonas and that it might have the potential to be used as therapeutic intervention in addition to antibiotics to combat infection in future.
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29
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Sionov RV, Steinberg D. Targeting the Holy Triangle of Quorum Sensing, Biofilm Formation, and Antibiotic Resistance in Pathogenic Bacteria. Microorganisms 2022; 10:1239. [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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Affiliation(s)
- Ronit Vogt Sionov
- The Biofilm Research Laboratory, The Institute of Biomedical and Oral Research, The Faculty of Dental Medicine, Hadassah Medical School, The Hebrew University, Jerusalem 9112102, Israel;
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30
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Unni R, Pintor KL, Diepold A, Unterweger D. Presence and absence of type VI secretion systems in bacteria. MICROBIOLOGY (READING, ENGLAND) 2022; 168. [PMID: 35467500 DOI: 10.1099/mic.0.001151] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The type VI secretion system (T6SS) is a molecular puncturing device that enables Gram-negative bacteria to kill competitors, manipulate host cells and take up nutrients. Who would want to miss such superpowers? Indeed, many studies show how widespread the secretion apparatus is among microbes. However, it is becoming evident that, on multiple taxonomic levels, from phyla to species and strains, some bacteria lack a T6SS. Here, we review who does and does not have a type VI secretion apparatus and speculate on the dynamic process of gaining and losing the secretion system to better understand its spread and distribution across the microbial world.
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Affiliation(s)
- Rahul Unni
- Max Planck Institute for Evolutionary Biology, August-Thienemann-Straße 2, 24306 Plön, Germany.,Institute for Experimental Medicine, Kiel University, Michaelisstraße 5, 24105 Kiel, Germany
| | - Katherine L Pintor
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Str. 10, 35043 Marburg, Germany
| | - Andreas Diepold
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Str. 10, 35043 Marburg, Germany
| | - Daniel Unterweger
- Max Planck Institute for Evolutionary Biology, August-Thienemann-Straße 2, 24306 Plön, Germany.,Institute for Experimental Medicine, Kiel University, Michaelisstraße 5, 24105 Kiel, Germany
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31
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Li H, Xia Y, Tian Z, Jin Y, Bai F, Cheng Z, Swietnicki W, Wu W, Pan X. Dihydrolipoamide Acetyltransferase AceF Influences the Type III Secretion System and Resistance to Oxidative Stresses through RsmY/Z in Pseudomonas aeruginosa. Microorganisms 2022; 10:microorganisms10030666. [PMID: 35336241 PMCID: PMC8950878 DOI: 10.3390/microorganisms10030666] [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: 01/11/2022] [Revised: 03/10/2022] [Accepted: 03/17/2022] [Indexed: 01/27/2023] Open
Abstract
Carbon metabolism plays an important role in bacterial physiology and pathogenesis. The type III secretion system (T3SS) of Pseudomonas aeruginosa is a virulence factor that contributes to acute infections. It has been demonstrated that bacterial metabolism affects the T3SS. Meanwhile, expression of T3SS genes is negatively regulated by the small RNAs RsmY and RsmZ. In this study, we studied the relationship between the dihydrolipoamide acetyltransferase gene aceF and the T3SS. Our results reveal an upregulation of RsmY and RsmZ in the aceF mutant, which represses the expression of the T3SS genes. Meanwhile, the aceF mutant is more tolerant to hydrogen peroxide. We demonstrate that the expression levels of the catalase KatB and the alkyl hydroperoxide reductase AhpB are increased in the aceF mutant. The simultaneous deletion of rsmY and rsmZ in the aceF mutant restored the expression levels of katB and ahpB, as well as bacterial susceptibility to hydrogen peroxide. Thus, we identify a novel role of AceF in the virulence and oxidative response of P. aeruginosa.
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Affiliation(s)
- Haozhou Li
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China; (H.L.); (Y.X.); (Z.T.); (Y.J.); (F.B.); (Z.C.); (W.W.)
| | - Yushan Xia
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China; (H.L.); (Y.X.); (Z.T.); (Y.J.); (F.B.); (Z.C.); (W.W.)
| | - Zhenyang Tian
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China; (H.L.); (Y.X.); (Z.T.); (Y.J.); (F.B.); (Z.C.); (W.W.)
| | - Yongxin Jin
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China; (H.L.); (Y.X.); (Z.T.); (Y.J.); (F.B.); (Z.C.); (W.W.)
| | - Fang Bai
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China; (H.L.); (Y.X.); (Z.T.); (Y.J.); (F.B.); (Z.C.); (W.W.)
| | - Zhihui Cheng
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China; (H.L.); (Y.X.); (Z.T.); (Y.J.); (F.B.); (Z.C.); (W.W.)
| | - Wieslaw Swietnicki
- Department of Immunology of Infectious Diseases, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, ul. R. Weigla 12, 53-114 Wroclaw, Poland;
| | - Weihui Wu
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China; (H.L.); (Y.X.); (Z.T.); (Y.J.); (F.B.); (Z.C.); (W.W.)
| | - Xiaolei Pan
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China; (H.L.); (Y.X.); (Z.T.); (Y.J.); (F.B.); (Z.C.); (W.W.)
- Correspondence:
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NrtR Mediated Regulation of H1-T6SS in Pseudomonas aeruginosa. Microbiol Spectr 2022; 10:e0185821. [PMID: 35196795 PMCID: PMC8865458 DOI: 10.1128/spectrum.01858-21] [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: 12/02/2022] Open
Abstract
NrtR is a Nudix-related transcriptional regulator that is distributed among diverse bacteria and plays an important role in modulating bacterial intracellular NAD homeostasis. Previously, we showed that NrtR influences the T3SS expression and pathogenesis of Pseudomonas aeruginosa and demonstrated that NrtR mediates T3SS regulation through the cAMP/Vfr pathway. In the present study, we found that mutation of the nrtR gene leads to upregulation of the Hcp secretion island-I type VI secretion system (H1-T6SS). Further analysis revealed that mutation of the nrtR gene results in upregulation of regulatory RNAs (RsmY/RsmZ) that are known to control the H1-T6SS by sequestration of RsmA or RsmN. Simultaneous deletion of rsmY/rsmZ reduced the expression of H1-T6SS in the ΔnrtR mutant. In addition, overexpression of either rsmA or rsmN in ΔnrtR decreased H1-T6SS expression. Chromatin immunoprecipitation (ChIP)-Seq and electrophoretic mobility shift assay (EMSA) analyses revealed that NrtR directly binds to the promoters of rsmY, rsmZ and tssA1 (first gene of the H1-T6SS operon). Overall, the results from this study reveal the molecular details of NrtR-mediated regulation of H1-T6SS in P. aeruginosa. IMPORTANCE NrtR is a Nudix-related transcriptional regulator and controls the NAD cofactor biosynthesis in bacteria. P. aeruginosa NrtR binds to the intergenic region between nadD2 and pcnA to repress the expression of the two operons, therefore controlling the NAD biosynthesis. We have previously reported that NrtR controls T3SS expression via the cAMP/Vfr pathway in P. aeruginosa. However, the global regulatory function and direct binding targets of the NrtR remain elusive in P. aeruginosa. This study reveals novel direct regulatory targets of the NrtR in P. aeruginosa, elucidating the molecular mechanism of NrtR-mediated regulation of H1-T6SS.
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Nie H, Xiao Y, Song M, Wu N, Peng Q, Duan W, Chen W, Huang Q. Wsp system oppositely modulates antibacterial activity and biofilm formation via FleQ-FleN complex in Pseudomonas putida. Environ Microbiol 2022; 24:1543-1559. [PMID: 35178858 DOI: 10.1111/1462-2920.15905] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 01/13/2022] [Indexed: 11/29/2022]
Abstract
Type VI secretion systems (T6SS) are specific antibacterial weapons employed by diverse bacteria to protect themselves from competitors. Pseudomonas putida KT2440 possesses a functional T6SS (K1-T6SS) and exhibits antibacterial activity towards a broad range of bacteria. Here we found that the Wsp signal transduction system regulated K1-T6SS expression via synthesizing the second messenger cyclic di-GMP (c-di-GMP), thus mediating antibacterial activity in P. putida. High-level c-di-GMP produced by Wsp system repressed the transcription of K1-T6SS genes in structural operon and vgrG1 operon. Transcriptional regulator FleQ and ATPase FleN functioned as repressors in the Wsp system-modulated K1-T6SS transcription. However, FleQ and FleN functioned as activators in biofilm formation, and Wsp system promoted biofilm formation largely in a FleQ/FleN-dependent manner. Furthermore, FleQ-FleN complex bound directly to the promoter of K1-T6SS structural operon in vitro, and c-di-GMP promoted the binding. Besides, P. putida biofilm cells showed higher c-di-GMP levels and lower antibacterial activity than planktonic cells. Overall, our findings reveal a mechanism by which Wsp system oppositely modulates antibacterial activity and biofilm formation via FleQ-FleN, and demonstrate the relationship between plankton/biofilm lifestyles and antibacterial activity in P. putida.
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Affiliation(s)
- Hailing Nie
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Yujie Xiao
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Miaomiao Song
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Nianqi Wu
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Qi Peng
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Wei Duan
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Wenli Chen
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Qiaoyun Huang
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, China.,Hubei Key Laboratory of Soil Environment and Pollution Remediation, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China
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34
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Qu J, Cai Z, Duan X, Zhang H, Cheng H, Han S, Yu K, Jiang Z, Zhang Y, Liu Y, Bai F, Liu Y, Liu L, Yang L. Pseudomonas aeruginosa modulates alginate biosynthesis and type VI secretion system in two critically ill COVID-19 patients. Cell Biosci 2022; 12:14. [PMID: 35139898 PMCID: PMC8827185 DOI: 10.1186/s13578-022-00748-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Accepted: 01/19/2022] [Indexed: 12/21/2022] Open
Abstract
Background COVID-19 pneumonia has caused huge impact on the health of infected patients and associated with high morbidity and mortality. Shift in the lung microbial ecology upon such viral infection often worsens the disease and increases host susceptibility to superinfections. Bacterial superinfection contributes to the aggravation of COVID-19 and poses a great challenge to clinical treatments. An in-depth investigation on superinfecting bacteria in COVID-19 patients might facilitate understanding of lung microenvironment post virus infections and superinfection mechanism. Results We analyzed the adaptation of two pairs of P. aeruginosa strains with the same MLST type isolated from two critical COVID-19 patients by combining sequencing analysis and phenotypic assays. Both P. aeruginosa strains were found to turn on alginate biosynthesis and attenuate type VI secretion system (T6SS) during short-term colonization in the COVID-19 patients, which results in excessive biofilm formation and virulence reduction-two distinct markers for chronic infections. The macrophage cytotoxicity test and intracellular reactive oxygen species measurement confirmed that the adapted P. aeruginosa strains reduced their virulence towards host cells and are better to escape from host immune clearance than their ancestors. Conclusion Our study suggests that SARS-CoV-2 infection can create a lung environment that allow rapid adaptive evolution of bacterial pathogens with genetic traits suitable for chronic infections. Supplementary Information The online version contains supplementary material available at 10.1186/s13578-022-00748-z.
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Affiliation(s)
- Jiuxin Qu
- Department of Clinical Laboratory, Shenzhen Third People's Hospital, Second Hospital Affiliated to Southern University of Science and Technology, Guangdong Provincial Clinical Research Center for Infectious Diseases (Tuberculosis), National Clinical Research Center for Infectious Diseases, Shenzhen, 518000, Guangdong, China
| | - Zhao Cai
- School of Medicine, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Xiangke Duan
- School of Medicine, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Han Zhang
- School of Medicine, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Hang Cheng
- School of Medicine, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Shuhong Han
- School of Medicine, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Kaiwei Yu
- School of Medicine, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Zhaofang Jiang
- Department of Clinical Laboratory, Shenzhen Third People's Hospital, Second Hospital Affiliated to Southern University of Science and Technology, Guangdong Provincial Clinical Research Center for Infectious Diseases (Tuberculosis), National Clinical Research Center for Infectious Diseases, Shenzhen, 518000, Guangdong, China
| | - Yingdan Zhang
- School of Medicine, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Yang Liu
- Medical Research Center, Southern University of Science and Technology Hospital, Shenzhen, 518055, China
| | - Fang Bai
- School of Biological Sciences, Nankai University, Tianjin, 300071, China
| | - Yingxia Liu
- Department of Clinical Laboratory, Shenzhen Third People's Hospital, Second Hospital Affiliated to Southern University of Science and Technology, Guangdong Provincial Clinical Research Center for Infectious Diseases (Tuberculosis), National Clinical Research Center for Infectious Diseases, Shenzhen, 518000, Guangdong, China.,Shenzhen Key Laboratory of Pathogen and Immunity, State Key Discipline of Infectious Disease, Shenzhen Third People's Hospital, Second Hospital Affiliated to Southern University of Science and Technology, Shenzhen, 518112, China
| | - Lei Liu
- Department of Clinical Laboratory, Shenzhen Third People's Hospital, Second Hospital Affiliated to Southern University of Science and Technology, Guangdong Provincial Clinical Research Center for Infectious Diseases (Tuberculosis), National Clinical Research Center for Infectious Diseases, Shenzhen, 518000, Guangdong, China. .,Shenzhen Key Laboratory of Pathogen and Immunity, State Key Discipline of Infectious Disease, Shenzhen Third People's Hospital, Second Hospital Affiliated to Southern University of Science and Technology, Shenzhen, 518112, China.
| | - Liang Yang
- Department of Clinical Laboratory, Shenzhen Third People's Hospital, Second Hospital Affiliated to Southern University of Science and Technology, Guangdong Provincial Clinical Research Center for Infectious Diseases (Tuberculosis), National Clinical Research Center for Infectious Diseases, Shenzhen, 518000, Guangdong, China. .,School of Medicine, Southern University of Science and Technology, Shenzhen, 518055, China. .,Shenzhen Key Laboratory for Gene Regulation and Systems Biology, Southern University of Science and Technology, Shenzhen, 518055, China.
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35
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Blanco-Romero E, Durán D, Garrido-Sanz D, Rivilla R, Martín M, Redondo-Nieto M. Transcriptomic analysis of Pseudomonas ogarae F113 reveals the antagonistic roles of AmrZ and FleQ during rhizosphere adaption. Microb Genom 2022; 8. [PMID: 35012704 PMCID: PMC8914362 DOI: 10.1099/mgen.0.000750] [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: 12/19/2022] Open
Abstract
Rhizosphere colonization by bacteria involves molecular and cellular mechanisms, such as motility and chemotaxis, biofilm formation, metabolic versatility, or biosynthesis of secondary metabolites, among others. Nonetheless, there is limited knowledge concerning the main regulatory factors that drive the rhizosphere colonization process. Here we show the importance of the AmrZ and FleQ transcription factors for adaption in the plant growth-promoting rhizobacterium (PGPR) and rhizosphere colonization model Pseudomonas ogarae F113. RNA-Seq analyses of P. ogarae F113 grown in liquid cultures either in exponential and stationary growth phase, and rhizosphere conditions, revealed that rhizosphere is a key driver of global changes in gene expression in this bacterium. Regarding the genetic background, this work has revealed that a mutation in fleQ causes considerably more alterations in the gene expression profile of this bacterium than a mutation in amrZ under rhizosphere conditions. The functional analysis has revealed that in P. ogarae F113, the transcription factors AmrZ and FleQ regulate genes involved in diverse bacterial functions. Notably, in the rhizosphere, these transcription factors antagonistically regulate genes related to motility, biofilm formation, nitrogen, sulfur, and amino acid metabolism, transport, signalling, and secretion, especially the type VI secretion systems. These results define the regulon of two important bifunctional transcriptional regulators in pseudomonads during the process of rhizosphere colonization.
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Affiliation(s)
- Esther Blanco-Romero
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Darwin 2, 28049 Madrid, Spain
| | - David Durán
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Darwin 2, 28049 Madrid, Spain
| | - Daniel Garrido-Sanz
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Darwin 2, 28049 Madrid, Spain.,Department of Fundamental Microbiology, University of Lausanne, CH-1015 Lausanne, Switzerland
| | - Rafael Rivilla
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Darwin 2, 28049 Madrid, Spain
| | - Marta Martín
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Darwin 2, 28049 Madrid, Spain
| | - Miguel Redondo-Nieto
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Darwin 2, 28049 Madrid, Spain
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36
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Allsopp LP, Collins ACZ, Hawkins E, Wood TE, Filloux A. RpoN/Sfa2-dependent activation of the Pseudomonas aeruginosa H2-T6SS and its cognate arsenal of antibacterial toxins. Nucleic Acids Res 2022; 50:227-243. [PMID: 34928327 PMCID: PMC8855297 DOI: 10.1093/nar/gkab1254] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 11/26/2021] [Accepted: 12/16/2021] [Indexed: 12/13/2022] Open
Abstract
Pseudomonas aeruginosa uses three type six secretion systems (H1-, H2- and H3-T6SS) to manipulate its environment, subvert host cells and for microbial competition. These T6SS machines are loaded with a variety of effectors/toxins, many being associated with a specific VgrG. How P. aeruginosa transcriptionally coordinates the main T6SS clusters and the multiple vgrG islands spread through the genome is unknown. Here we show an unprecedented level of control with RsmA repressing most known T6SS-related genes. Moreover, each of the H2- and H3-T6SS clusters encodes a sigma factor activator (SFA) protein called, Sfa2 and Sfa3, respectively. SFA proteins are enhancer binding proteins necessary for the sigma factor RpoN. Using a combination of RNA-seq, ChIP-seq and molecular biology approaches, we demonstrate that RpoN coordinates the T6SSs of P. aeruginosa by activating the H2-T6SS but repressing the H1- and H3-T6SS. Furthermore, RpoN and Sfa2 control the expression of the H2-T6SS-linked VgrGs and their effector arsenal to enable very effective interbacterial killing. Sfa2 is specific as Sfa3 from the H3-T6SS cannot complement loss of Sfa2. Our study further delineates the regulatory mechanisms that modulate the deployment of an arsenal of T6SS effectors likely enabling P. aeruginosa to adapt to a range of environmental conditions.
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Affiliation(s)
- Luke P Allsopp
- Department of Life Sciences, MRC Centre for Molecular
Bacteriology and Infection, Imperial College London,
London, UK
- National Heart and Lung Institute, Imperial College
London, London, UK
| | - Alice C Z Collins
- National Heart and Lung Institute, Imperial College
London, London, UK
| | - Eleanor Hawkins
- Department of Life Sciences, MRC Centre for Molecular
Bacteriology and Infection, Imperial College London,
London, UK
| | - Thomas E Wood
- Department of Life Sciences, MRC Centre for Molecular
Bacteriology and Infection, Imperial College London,
London, UK
| | - Alain Filloux
- Department of Life Sciences, MRC Centre for Molecular
Bacteriology and Infection, Imperial College London,
London, UK
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37
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Antimicrobial Weapons of Pseudomonas aeruginosa. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1386:223-256. [DOI: 10.1007/978-3-031-08491-1_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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38
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Cell Envelope Stress Response in Pseudomonas aeruginosa. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1386:147-184. [DOI: 10.1007/978-3-031-08491-1_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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39
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Zwe YH, Yadav M, Zhen Ten MM, Srinivasan M, Jobichen C, Sivaraman J, Li D. Bacterial Antagonism of Chromobacterium haemolyticum and Characterization of its Putative Type VI Secretion System. Res Microbiol 2021; 173:103918. [PMID: 34906677 DOI: 10.1016/j.resmic.2021.103918] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 12/08/2021] [Accepted: 12/08/2021] [Indexed: 10/19/2022]
Abstract
This study reports the isolation of a new Chromobacterium haemolyticum strain named WI5 from a hydroponic farming facility. WI5 exhibited remarkable bacterial antagonistic properties, eliminating Salmonella, Escherichia coli, Listeria monocytogenes and Staphylococcus aureus (initial inoculum load ∼105 CFU/ml) in dual-species co-culture biofilms. Antagonism was strictly contact-dependent and highly influenced by nutrient availability. Next, we identified a complete suite of putative Type VI secretion system (T6SS) genes in the WI5 genome, annotated the gene locus architecture, and determined the crystal structure of hallmark T6SS tube protein Hcp1, which revealed a hexameric ring structure with an outer and inner diameter of 77 and 45Å, respectively. Structural comparison with homologs showed differences in the key loops connecting the β-strands in which the conserved residues are located, suggesting a role of these residues in the protein function. The T6SS is well-known to facilitate interbacterial competition, and the putative T6SS characterized herein might be responsible for the remarkable antagonism by C. haemolyticum WI5. Collectively, these findings shed light on the nature of bacterial antagonism and a putative key virulence determinant of C. haemolyticum, which might aid in further understanding its potential ecological role in natural habitats.
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Affiliation(s)
- Ye Htut Zwe
- Department of Food Science & Technology, 2 Science Drive 2, Faculty of Science, National University of Singapore, Singapore 117543
| | - Manisha Yadav
- Department of Biological Sciences, 14 Science Drive 4, Faculty of Science, National University of Singapore, Singapore 117543
| | - Michelle Mei Zhen Ten
- Department of Food Science & Technology, 2 Science Drive 2, Faculty of Science, National University of Singapore, Singapore 117543
| | - Mahalashmi Srinivasan
- Department of Biological Sciences, 14 Science Drive 4, Faculty of Science, National University of Singapore, Singapore 117543
| | - Chacko Jobichen
- Department of Biological Sciences, 14 Science Drive 4, Faculty of Science, National University of Singapore, Singapore 117543
| | - J Sivaraman
- Department of Biological Sciences, 14 Science Drive 4, Faculty of Science, National University of Singapore, Singapore 117543
| | - Dan Li
- Department of Food Science & Technology, 2 Science Drive 2, Faculty of Science, National University of Singapore, Singapore 117543.
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40
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Pan X, Tang M, You J, Osire T, Sun C, Fu W, Yi G, Yang T, Yang ST, Rao Z. PsrA is a novel regulator contributes to antibiotic synthesis, bacterial virulence, cell motility and extracellular polysaccharides production in Serratia marcescens. Nucleic Acids Res 2021; 50:127-148. [PMID: 34893884 PMCID: PMC8754645 DOI: 10.1093/nar/gkab1186] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 11/13/2021] [Accepted: 12/03/2021] [Indexed: 12/23/2022] Open
Abstract
Serratia marcescens is a Gram-negative bacterium of the Enterobacteriaceae family that can produce numbers of biologically active secondary metabolites. However, our understanding of the regulatory mechanisms behind secondary metabolites biosynthesis in S. marcescens remains limited. In this study, we identified an uncharacterized LysR family transcriptional regulator, encoding gene BVG90_12635, here we named psrA, that positively controlled prodigiosin synthesis in S. marcescens. This phenotype corresponded to PsrA positive control of transcriptional of the prodigiosin-associated pig operon by directly binding to a regulatory binding site (RBS) and an activating binding site (ABS) in the promoter region of the pig operon. We demonstrated that L-proline is an effector for the PsrA, which enhances the binding affinity of PsrA to its target promoters. Using transcriptomics and further experiments, we show that PsrA indirectly regulates pleiotropic phenotypes, including serrawettin W1 biosynthesis, extracellular polysaccharide production, biofilm formation, swarming motility and T6SS-mediated antibacterial activity in S. marcescens. Collectively, this study proposes that PsrA is a novel regulator that contributes to antibiotic synthesis, bacterial virulence, cell motility and extracellular polysaccharides production in S. marcescens and provides important clues for future studies exploring the function of the PsrA and PsrA-like proteins which are widely present in many other bacteria.
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Affiliation(s)
- Xuewei Pan
- Key Laboratory of Industrial Biotechnology of the Ministry of Education, Laboratory of Applied Microorganisms and Metabolic Engineering, School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Mi Tang
- Key Laboratory of Industrial Biotechnology of the Ministry of Education, Laboratory of Applied Microorganisms and Metabolic Engineering, School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Jiajia You
- Key Laboratory of Industrial Biotechnology of the Ministry of Education, Laboratory of Applied Microorganisms and Metabolic Engineering, School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Tolbert Osire
- Key Laboratory of Industrial Biotechnology of the Ministry of Education, Laboratory of Applied Microorganisms and Metabolic Engineering, School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Changhao Sun
- Key Laboratory of Industrial Biotechnology of the Ministry of Education, Laboratory of Applied Microorganisms and Metabolic Engineering, School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Weilai Fu
- Key Laboratory of Industrial Biotechnology of the Ministry of Education, Laboratory of Applied Microorganisms and Metabolic Engineering, School of Biotechnology, Jiangnan University, Wuxi 214122, China.,Fujian Dabeinong Aquatic Sci. & Tech. Co., Ltd., Zhangzhou 363500, China
| | - Ganfeng Yi
- Fujian Dabeinong Aquatic Sci. & Tech. Co., Ltd., Zhangzhou 363500, China
| | - Taowei Yang
- Key Laboratory of Industrial Biotechnology of the Ministry of Education, Laboratory of Applied Microorganisms and Metabolic Engineering, School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Shang-Tian Yang
- Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, OH 43210, USA
| | - Zhiming Rao
- Key Laboratory of Industrial Biotechnology of the Ministry of Education, Laboratory of Applied Microorganisms and Metabolic Engineering, School of Biotechnology, Jiangnan University, Wuxi 214122, China
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41
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Genomic and Metabolic Characteristics of the Pathogenicity in Pseudomonas aeruginosa. Int J Mol Sci 2021; 22:ijms222312892. [PMID: 34884697 PMCID: PMC8657582 DOI: 10.3390/ijms222312892] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 11/26/2021] [Accepted: 11/27/2021] [Indexed: 01/22/2023] Open
Abstract
In recent years, the effectiveness of antimicrobials in the treatment of Pseudomonas aeruginosa infections has gradually decreased. This pathogen can be observed in several clinical cases, such as pneumonia, urinary tract infections, sepsis, in immunocompromised hosts, such as neutropenic cancer, burns, and AIDS patients. Furthermore, Pseudomonas aeruginosa causes diseases in both livestock and pets. The highly flexible and versatile genome of P. aeruginosa allows it to have a high rate of pathogenicity. The numerous secreted virulence factors, resulting from its numerous secretion systems, the multi-resistance to different classes of antibiotics, and the ability to produce biofilms are pathogenicity factors that cause numerous problems in the fight against P. aeruginosa infections and that must be better understood for an effective treatment. Infections by P. aeruginosa represent, therefore, a major health problem and, as resistance genes can be disseminated between the microbiotas associated with humans, animals, and the environment, this issue needs be addressed on the basis of an One Health approach. This review intends to bring together and describe in detail the molecular and metabolic pathways in P. aeruginosa's pathogenesis, to contribute for the development of a more targeted therapy against this pathogen.
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42
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Gallegos-Monterrosa R, Coulthurst SJ. The ecological impact of a bacterial weapon: microbial interactions and the Type VI secretion system. FEMS Microbiol Rev 2021; 45:fuab033. [PMID: 34156081 PMCID: PMC8632748 DOI: 10.1093/femsre/fuab033] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 06/20/2021] [Indexed: 12/13/2022] Open
Abstract
Bacteria inhabit all known ecological niches and establish interactions with organisms from all kingdoms of life. These interactions are mediated by a wide variety of mechanisms and very often involve the secretion of diverse molecules from the bacterial cells. The Type VI secretion system (T6SS) is a bacterial protein secretion system that uses a bacteriophage-like machinery to secrete a diverse array of effectors, usually translocating them directly into neighbouring cells. These effectors display toxic activity in the recipient cell, making the T6SS an effective weapon during inter-bacterial competition and interactions with eukaryotic cells. Over the last two decades, microbiology research has experienced a shift towards using systems-based approaches to study the interactions between diverse organisms and their communities in an ecological context. Here, we focus on this aspect of the T6SS. We consider how our perspective of the T6SS has developed and examine what is currently known about the impact that bacteria deploying the T6SS can have in diverse environments, including niches associated with plants, insects and mammals. We consider how T6SS-mediated interactions can affect host organisms by shaping their microbiota, as well as the diverse interactions that can be established between different microorganisms through the deployment of this versatile secretion system.
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Affiliation(s)
| | - Sarah J Coulthurst
- School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK
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43
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Dadashi M, Chen L, Nasimian A, Ghavami S, Duan K. Putative RNA Ligase RtcB Affects the Switch between T6SS and T3SS in Pseudomonas aeruginosa. Int J Mol Sci 2021; 22:12561. [PMID: 34830443 PMCID: PMC8619066 DOI: 10.3390/ijms222212561] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 11/04/2021] [Accepted: 11/06/2021] [Indexed: 01/22/2023] Open
Abstract
The opportunistic pathogen Pseudomonas aeruginosa is a significant cause of infection in immunocompromised individuals, cystic fibrosis patients, and burn victims. To benefit its survival, the bacterium adapt to either a motile or sessile lifestyle when infecting the host. The motile bacterium has an often activated type III secretion system (T3SS), which is virulent to the host, whereas the sessile bacterium harbors an active T6SS and lives in biofilms. Regulatory pathways involving Gac-Rsm or secondary messengers such as c-di-GMP determine which lifestyle is favorable for P. aeruginosa. Here, we introduce the RNA binding protein RtcB as a modulator of the switch between motile and sessile bacterial lifestyles. Using the wild-type P. aeruginosa PAO1, and a retS mutant PAO1(∆retS) in which T3SS is repressed and T6SS active, we show that deleting rtcB led to simultaneous expression of T3SS and T6SS in both PAO1(∆rtcB) and PAO1(∆rtcB∆retS). The deletion of rtcB also increased biofilm formation in PAO1(∆rtcB) and restored the motility of PAO1(∆rtcB∆retS). RNA-sequencing data suggested RtcB as a global modulator affecting multiple virulence factors, including bacterial secretion systems. Competitive killing and infection assays showed that the three T6SS systems (H1, H2, and H3) in PAO1(∆rtcB) were activated into a functional syringe, and could compete with Escherichia coli and effectively infect lettuce. Western blotting and RT-PCR results showed that RtcB probably exerted its function through RsmA in PAO1(∆rtcB∆retS). Quantification of c-di-GMP showed an elevated intracellular levels in PAO1(∆rtcB), which likely drove the switch between T6SS and T3SS, and contributed to the altered phenotypes and characteristics observed. Our data demonstrate a pivotal role of RtcB in the virulence of P. aeruginosa by controlling multiple virulence determinants, such as biofilm formation, motility, pyocyanin production, T3SS, and T6SS secretion systems towards eukaryotic and prokaryotic cells. These findings suggest RtcB as a potential target for controlling P. aeruginosa colonization, establishment, and pathogenicity.
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Affiliation(s)
- Maryam Dadashi
- Department of Oral Biology, Rady Faculty of Health Sciences, Dr. Gerald Niznick College of Dentistry, University of Manitoba, Winnipeg, MB R3E 0W2, Canada;
| | - Lin Chen
- College of Life Sciences, Northwest University, Xi’an 710069, China;
| | - Ahmad Nasimian
- Department of Human Anatomy and Cell Science, Rady Faculty of Health Sciences, Max Rady College of Medicine, University of Manitoba, Winnipeg, MB R3E 0W2, Canada; (A.N.); (S.G.)
| | - Saeid Ghavami
- Department of Human Anatomy and Cell Science, Rady Faculty of Health Sciences, Max Rady College of Medicine, University of Manitoba, Winnipeg, MB R3E 0W2, Canada; (A.N.); (S.G.)
| | - Kangmin Duan
- Department of Oral Biology, Rady Faculty of Health Sciences, Dr. Gerald Niznick College of Dentistry, University of Manitoba, Winnipeg, MB R3E 0W2, Canada;
- Department of Medical Microbiology and Infectious Disease, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB R3E 0W2, Canada
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Brinkman FSL, Winsor GL, Done RE, Filloux A, Francis VI, Goldberg JB, Greenberg EP, Han K, Hancock REW, Haney CH, Häußler S, Klockgether J, Lamont IL, Levesque RC, Lory S, Nikel PI, Porter SL, Scurlock MW, Schweizer HP, Tümmler B, Wang M, Welch M. The Pseudomonas aeruginosa whole genome sequence: A 20th anniversary celebration. Adv Microb Physiol 2021; 79:25-88. [PMID: 34836612 DOI: 10.1016/bs.ampbs.2021.07.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Toward the end of August 2000, the 6.3 Mbp whole genome sequence of Pseudomonas aeruginosa strain PAO1 was published. With 5570 open reading frames (ORFs), PAO1 had the largest microbial genome sequenced up to that point in time-including a large proportion of metabolic, transport and antimicrobial resistance genes supporting its ability to colonize diverse environments. A remarkable 9% of its ORFs were predicted to encode proteins with regulatory functions, providing new insight into bacterial network complexity as a function of network size. In this celebratory article, we fast forward 20 years, and examine how access to this resource has transformed our understanding of P. aeruginosa. What follows is more than a simple review or commentary; we have specifically asked some of the leaders in the field to provide personal reflections on how the PAO1 genome sequence, along with the Pseudomonas Community Annotation Project (PseudoCAP) and Pseudomonas Genome Database (pseudomonas.com), have contributed to the many exciting discoveries in this field. In addition to bringing us all up to date with the latest developments, we also ask our contributors to speculate on how the next 20 years of Pseudomonas research might pan out.
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Affiliation(s)
- Fiona S L Brinkman
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada
| | - Geoffrey L Winsor
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada
| | - Rachel E Done
- Department of Pediatrics, Division of Pulmonary, Allergy and Immunology, Cystic Fibrosis, and Sleep, Emory Children's Center for Cystic Fibrosis and Airway Disease Research, Emory University School of Medicine, Atlanta, GA, United States
| | - Alain Filloux
- Department of Life Sciences, MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, United Kingdom
| | - Vanessa I Francis
- Geoffrey Pope Building, University of Exeter, Exeter, United Kingdom
| | - Joanna B Goldberg
- Department of Pediatrics, Division of Pulmonary, Allergy and Immunology, Cystic Fibrosis, and Sleep, Emory Children's Center for Cystic Fibrosis and Airway Disease Research, Emory University School of Medicine, Atlanta, GA, United States
| | - E Peter Greenberg
- Department of Microbiology, University of Washington, Seattle, WA, United States
| | - Kook Han
- Department of Microbiology, Harvard Medical School, Boston, MA, United States
| | | | - Cara H Haney
- Department of Microbiology and Immunology, The University of British Columbia, Vancouver, BC, Canada
| | - Susanne Häußler
- Department of Molecular Bacteriology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Jens Klockgether
- Klinik für Pädiatrische Pneumologie, Allergologie und Neonatologie, Medizinische Hochschule Hannover, Hannover, Germany
| | - Iain L Lamont
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
| | - Roger C Levesque
- Institut de biologie intégrative et des systèmes (IBIS), Pavillon Charles-Eugène Marchand, Faculté of Médicine, Université Laval, Québec City, QC, Canada
| | - Stephen Lory
- Department of Microbiology, Harvard Medical School, Boston, MA, United States
| | - Pablo I Nikel
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Lyngby, Denmark
| | - Steven L Porter
- Geoffrey Pope Building, University of Exeter, Exeter, United Kingdom
| | | | - Herbert P Schweizer
- Pathogen and Microbiome Institute, Northern Arizona University, Flagstaff, AZ, United States
| | - Burkhard Tümmler
- Klinik für Pädiatrische Pneumologie, Allergologie und Neonatologie, Medizinische Hochschule Hannover, Hannover, Germany
| | - Meng Wang
- Department of Biochemistry (Hopkins Building), University of Cambridge, Cambridge, United Kingdom
| | - Martin Welch
- Department of Biochemistry (Hopkins Building), University of Cambridge, Cambridge, United Kingdom.
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Lin J, Xu L, Yang J, Wang Z, Shen X. Beyond dueling: roles of the type VI secretion system in microbiome modulation, pathogenesis and stress resistance. STRESS BIOLOGY 2021; 1:11. [PMID: 37676535 PMCID: PMC10441901 DOI: 10.1007/s44154-021-00008-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Accepted: 08/09/2021] [Indexed: 09/08/2023]
Abstract
Bacteria inhabit diverse and dynamic environments, where nutrients may be limited and toxic chemicals can be prevalent. To adapt to these stressful conditions, bacteria have evolved specialized protein secretion systems, such as the type VI secretion system (T6SS) to facilitate their survival. As a molecular syringe, the T6SS expels various effectors into neighboring bacterial cells, eukaryotic cells, or the extracellular environment. These effectors improve the competitive fitness and environmental adaption of bacterial cells. Although primarily recognized as antibacterial weapons, recent studies have demonstrated that T6SSs have functions beyond interspecies competition. Here, we summarize recent research on the role of T6SSs in microbiome modulation, pathogenesis, and stress resistance.
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Affiliation(s)
- Jinshui Lin
- Shaanxi Key Laboratory of Chinese Jujube, College of Life Sciences, Yan'an University, Yan'an, Shaanxi, 716000, People's Republic of China
| | - Lei Xu
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, People's Republic of China
| | - Jianshe Yang
- Shaanxi Key Laboratory of Chinese Jujube, College of Life Sciences, Yan'an University, Yan'an, Shaanxi, 716000, People's Republic of China
| | - Zhuo Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, People's Republic of China
| | - Xihui Shen
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, People's Republic of China.
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46
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The two-component system FleS/FleR represses H1-T6SS via c-di-GMP signaling in Pseudomonas aeruginosa. Appl Environ Microbiol 2021; 88:e0165521. [PMID: 34731046 DOI: 10.1128/aem.01655-21] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The type VI secretion system (T6SS) is an important translocation apparatus that is widely employed by Gram-negative bacteria to deliver toxic effectors into eukaryotic and prokaryotic target cells, causing host damage and providing competitive advantages in polymicrobial environments. The genome of P. aeruginosa harbors three T6SS clusters (H1-T6SS, H2-T6SS, H3-T6SS). Activities of these systems are tightly regulated by a complicated signaling network which remains largely elusive. In this study, we focused on a previously characterized two-component system FleS/FleR and performed comparative transcriptome analysis between the PAO1 wild-type strain and its isogenic ΔfleR mutant, which revealed the important role of FleS/FleR in regulating multiple physiological pathways including T6SS. Gene expression and bacterial killing assays showed that the expression and activity of H1-T6SS are repressed in the wild-type strain owing to the high intracellular c-di-GMP content. Further explorations demonstrated that c-di-GMP relies on the transcription factor FleQ to repress H1-T6SS and its synthesis is controlled by a global regulator AmrZ which is induced by the active FleS/FleR. Interestingly, FleS/FleR regulates H1-T6SS in PAO1 is independent of RetS which is known to regulate H1-T6SS by controlling the central post-transcriptional factor RsmA. Together, our results identified a novel regulator of H1-T6SS and provided detailed mechanisms of this signaling pathway in PAO1. IMPORTANCE P. aeruginosa is an opportunistic human pathogen distributed widely in the environment. The genome of this pathogen contains three T6SS clusters which contribute significantly to its virulence. Understanding the complex regulatory network that controls the activity of T6SS is essential for the development of effective therapeutic treatments for P. aeruginosa infections. In this study, transcriptome analysis led to the identification of a novel regulator FleS/FleR which inversely regulates H1-T6SS and H2-T6SS in P. aeruginosa PAO1. We further revealed a detailed FleS/FleR-mediated regulatory pathway of H1-T6SS in PAO1 which involves two additional transcriptional regulators AmrZ and FleQ and the second messenger c-di-GMP, providing important implications to develop novel anti-infective strategies and antimicrobial drugs.
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Song Y, Zhang S, Luo G, Shen Y, Li C, Zhu Y, Huang Q, Mou X, Tang X, Liu T, Wu S, Tong A, He Y, Bao R. Type II Antitoxin HigA Is a Key Virulence Regulator in Pseudomonas aeruginosa. ACS Infect Dis 2021; 7:2930-2940. [PMID: 34554722 DOI: 10.1021/acsinfecdis.1c00401] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Bacterial type II toxin-antitoxin (TA) systems are abundant genetic elements and are involved in a diverse array of physiological processes. These systems encode an antitoxin protein that directly binds and effectively neutralizes the protein toxin. Recent studies have highlighted the key roles of type II TA modules in bacterial virulence and pathogenesis, but the underlying mechanisms remain unclear. Here, we investigated the antitoxin HigA in Pseudomonas aeruginosa infection. Proteomic analysis of the higA deletion strain revealed an enhanced expression of pathogenic proteins. We further verified that HigA negatively controlled T3SS and T6SS expression by directly interacting with the promoter regions of the regulators amrZ and exsA, respectively. In other words, the reversal of HigA-mediated transcriptional inhibition on stress stimulation could induce virulence genes. These findings confirm the crucial roles of the type II antitoxin in bacterial infection, which highlights the potential of the HigBA TA system as an antibacterial treatment target.
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Affiliation(s)
- Yingjie Song
- Center of Infectious Diseases, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University and Collaborative Innovation Center, Chengdu 610093, China
| | - Siping Zhang
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, P.R. China
| | - Guihua Luo
- Center of Infectious Diseases, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University and Collaborative Innovation Center, Chengdu 610093, China
| | - Yalin Shen
- Center of Infectious Diseases, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University and Collaborative Innovation Center, Chengdu 610093, China
| | - Changcheng Li
- Center of Infectious Diseases, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University and Collaborative Innovation Center, Chengdu 610093, China
| | - Yibo Zhu
- Center of Infectious Diseases, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University and Collaborative Innovation Center, Chengdu 610093, China
| | - Qin Huang
- Center of Infectious Diseases, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University and Collaborative Innovation Center, Chengdu 610093, China
| | - Xingyu Mou
- Center of Infectious Diseases, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University and Collaborative Innovation Center, Chengdu 610093, China
| | - Xinyue Tang
- Center of Infectious Diseases, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University and Collaborative Innovation Center, Chengdu 610093, China
| | - Tonggen Liu
- Center of Infectious Diseases, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University and Collaborative Innovation Center, Chengdu 610093, China
| | - Siying Wu
- Department of Laboratory Medicine, West China Hospital, Sichuan University, Chengdu 610044, China
| | - Aiping Tong
- Center of Infectious Diseases, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University and Collaborative Innovation Center, Chengdu 610093, China
| | - Yongxing He
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, P.R. China
| | - Rui Bao
- Center of Infectious Diseases, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University and Collaborative Innovation Center, Chengdu 610093, China
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Nolan LM, Cain AK, Clamens T, Furniss RCD, Manoli E, Sainz-Polo MA, Dougan G, Albesa-Jové D, Parkhill J, Mavridou DA, Filloux A. Identification of Tse8 as a Type VI secretion system toxin from Pseudomonas aeruginosa that targets the bacterial transamidosome to inhibit protein synthesis in prey cells. Nat Microbiol 2021; 6:1199-1210. [PMID: 34413503 PMCID: PMC7611593 DOI: 10.1038/s41564-021-00950-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 07/15/2021] [Indexed: 02/07/2023]
Abstract
The Type VI secretion system (T6SS) is a bacterial nanomachine that delivers toxic effectors to kill competitors or subvert some of their key functions. Here, we use transposon directed insertion-site sequencing to identify T6SS toxins associated with the H1-T6SS, one of the three T6SS machines found in Pseudomonas aeruginosa. This approach identified several putative toxin-immunity pairs, including Tse8-Tsi8. Full characterization of this protein pair demonstrated that Tse8 is delivered by the VgrG1a spike complex into prey cells where it targets the transamidosome, a multiprotein complex involved in protein synthesis in bacteria that lack either one, or both, of the asparagine and glutamine transfer RNA synthases. Biochemical characterization of the interactions between Tse8 and the transamidosome components GatA, GatB and GatC suggests that the presence of Tse8 alters the fine-tuned stoichiometry of the transamidosome complex, and in vivo assays demonstrate that Tse8 limits the ability of prey cells to synthesize proteins. These data expand the range of cellular components targeted by the T6SS by identifying a T6SS toxin affecting protein synthesis and validate the use of a transposon directed insertion site sequencing-based global genomics approach to expand the repertoire of T6SS toxins in T6SS-encoding bacteria.
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Affiliation(s)
- Laura M. Nolan
- MRC Centre for Molecular Bacteriology and Infection (CMBI), Department of Life Sciences, Imperial College London, London, SW7 2AZ, United Kingdom
| | - Amy K. Cain
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA, United Kingdom
| | - Thomas Clamens
- MRC Centre for Molecular Bacteriology and Infection (CMBI), Department of Life Sciences, Imperial College London, London, SW7 2AZ, United Kingdom
| | - R. Christopher D. Furniss
- MRC Centre for Molecular Bacteriology and Infection (CMBI), Department of Life Sciences, Imperial College London, London, SW7 2AZ, United Kingdom
| | - Eleni Manoli
- MRC Centre for Molecular Bacteriology and Infection (CMBI), Department of Life Sciences, Imperial College London, London, SW7 2AZ, United Kingdom
| | - Maria A. Sainz-Polo
- Structural Biology Unit, CIC bioGUNE, Bizkaia Technology Park, 48160 Derio, Spain
| | - Gordon Dougan
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA, United Kingdom
| | - David Albesa-Jové
- Structural Biology Unit, CIC bioGUNE, Bizkaia Technology Park, 48160 Derio, Spain,IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
| | - Julian Parkhill
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA, United Kingdom
| | - Despoina A.I. Mavridou
- MRC Centre for Molecular Bacteriology and Infection (CMBI), Department of Life Sciences, Imperial College London, London, SW7 2AZ, United Kingdom,Department of Molecular Biosciences, University of Texas at Austin, Austin, 78712, Texas, USA,Correspondence to Alain Filloux: ; Despoina Mavridou:
| | - Alain Filloux
- MRC Centre for Molecular Bacteriology and Infection (CMBI), Department of Life Sciences, Imperial College London, London, SW7 2AZ, United Kingdom,Correspondence to Alain Filloux: ; Despoina Mavridou:
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49
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Specific and Global RNA Regulators in Pseudomonas aeruginosa. Int J Mol Sci 2021; 22:ijms22168632. [PMID: 34445336 PMCID: PMC8395346 DOI: 10.3390/ijms22168632] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 08/05/2021] [Accepted: 08/08/2021] [Indexed: 01/20/2023] Open
Abstract
Pseudomonas aeruginosa (Pae) is an opportunistic pathogen showing a high intrinsic resistance to a wide variety of antibiotics. It causes nosocomial infections that are particularly detrimental to immunocompromised individuals and to patients suffering from cystic fibrosis. We provide a snapshot on regulatory RNAs of Pae that impact on metabolism, pathogenicity and antibiotic susceptibility. Different experimental approaches such as in silico predictions, co-purification with the RNA chaperone Hfq as well as high-throughput RNA sequencing identified several hundreds of regulatory RNA candidates in Pae. Notwithstanding, using in vitro and in vivo assays, the function of only a few has been revealed. Here, we focus on well-characterized small base-pairing RNAs, regulating specific target genes as well as on larger protein-binding RNAs that sequester and thereby modulate the activity of translational repressors. As the latter impact large gene networks governing metabolism, acute or chronic infections, these protein-binding RNAs in conjunction with their cognate proteins are regarded as global post-transcriptional regulators.
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50
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Abstract
The T6SS is a microscopic harpoon that bacteria use to deliver toxins into neighboring cells. While its complex assembly process has been extensively studied, it remains unclear how the two forms (long and short) of the pivotal TssA protein affect T6SS function. TssA promotes baseplate formation, orchestrates sheath extension and, in its long form, interacts with a partner protein to anchor the extending sheath at the opposing side of the cell for up to 10 min. Here we demonstrate that short TssA proteins assist sheath stabilization by associating with a yet undescribed class of T6SS proteins that accumulate at the baseplate. These T6SSs fire in seconds; therefore, this discovery provides insight into the mechanism underpinning the different fighting strategies observed across T6SS-carrying bacteria. The type VI secretion system (T6SS) is a phage-derived contractile nanomachine primarily involved in interbacterial competition. Its pivotal component, TssA, is indispensable for the assembly of the T6SS sheath structure, the contraction of which propels a payload of effector proteins into neighboring cells. Despite their key function, TssA proteins exhibit unexpected diversity and exist in two major forms, a short form (TssAS) and a long form (TssAL). While TssAL proteins interact with a partner, called TagA, to anchor the distal end of the extended sheath, the mechanism for the stabilization of TssAS-containing T6SSs remains unknown. Here we discover a class of structural components that interact with short TssA proteins and contribute to T6SS assembly by stabilizing the polymerizing sheath from the baseplate. We demonstrate that the presence of these components is important for full sheath extension and optimal firing. Moreover, we show that the pairing of each form of TssA with a different class of sheath stabilization proteins results in T6SS apparatuses that either reside in the cell for some time or fire immediately after sheath extension. We propose that this diversity in firing dynamics could contribute to the specialization of the T6SS to suit bacterial lifestyles in diverse environmental niches.
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