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Herrou J, My L, Monteil CL, Bergot M, Jain R, Martinez E, Mignot T. Tad pili with adaptable tips mediate contact-dependent killing during bacterial predation. Nat Commun 2025; 16:4425. [PMID: 40360469 PMCID: PMC12075869 DOI: 10.1038/s41467-025-58967-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2024] [Accepted: 04/03/2025] [Indexed: 05/15/2025] Open
Abstract
The predatory bacterium, Myxococcus xanthus, kills its prey by contact, using a putative Tight Adherence pilus, known as the Kil system, along with a protein complex resembling the basal body a type-III secretion system, named the "needleless" T3SS*. In this work, we provide direct evidence that Myxococcus polymerizes a Kil pilus at the prey contact site, which is constituted by the major pilin KilP. We also genetically demonstrate that the predation function of this pilus is linked to four different minor pilin complexes, which work in specific combinations to detect and kill phylogenetically diverse bacterial species. Structural models of the Kil pilus suggest that these minor pilin complexes form interchangeable "Tips", exposing variable domains at the extremity of the pilus to interact with prey cells. Remarkably, the activity of these Tips also depends on the T3SS*, revealing a tight functional connection between the Kil system and the T3SS*. While these Tips are mostly restricted to predatory bacteria, genomic and structural analyses suggest that in other bacteria, including pathogens, Tad pili are also customized and functionalized by similar minor pilin complexes exposing variable domains.
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Affiliation(s)
| | - Laetitia My
- Aix Marseille Univ, CNRS, LCB, Marseille, France
| | | | - Marine Bergot
- Aix-Marseille Univ, CEA, CNRS, BIAM, Saint-Paul-lez-Durance, France
| | - Rikesh Jain
- Aix Marseille Univ, CNRS, LCB, Marseille, France
| | | | - Tâm Mignot
- Aix Marseille Univ, CNRS, LCB, Marseille, France.
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Marcos-Vilchis A, Espinosa N, Alvarez AF, Puente JL, Soto JE, González-Pedrajo B. On the role of the sorting platform in hierarchical type III secretion regulation in enteropathogenic Escherichia coli. J Bacteriol 2025; 207:e0044624. [PMID: 40029102 PMCID: PMC11925242 DOI: 10.1128/jb.00446-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2024] [Accepted: 02/09/2025] [Indexed: 03/05/2025] Open
Abstract
The virulence of enteropathogenic Escherichia coli (EPEC) depends on a type III secretion system (T3SS), a membrane-spanning apparatus that injects effector proteins into the cytoplasm of target enterocytes. The T3SS, or injectisome, is a self-assembled nanomachine whose biogenesis and function rely on the ordered secretion of three distinct categories of proteins: early, middle, and late type III substrates. In EPEC, this hierarchical secretion is assisted by several cytosolic protein complexes at the base of the injectisome. Among these, the sorting platform is involved in the recognition and sequential loading of the different classes of T3-substrates. In addition, a heterotrimeric gatekeeper complex, also known as a molecular switch, operates in concert with components of the T3SS export apparatus to guarantee the delivery of middle substrates prior to late substrate secretion. In this study, we showed that the sorting platform is differentially required for the secretion of distinct categories of substrates. Moreover, we demonstrated a cooperative interplay and protein-protein interactions between the sorting platform and the gatekeeper complex for proper middle and late substrate docking and secretion. Overall, our results provide new insights into the intricate molecular mechanisms that regulate protein secretion hierarchy during T3SS assembly.IMPORTANCEEnteropathogenic Escherichia coli employs a type III secretion system to deliver virulence proteins directly into host cells, disrupting multiple cellular processes to promote infection. This multiprotein system assembles in a precise stepwise manner, with specific proteins being recruited and secreted at distinct stages. The sorting platform and the gatekeeper complex play critical roles in regulating this process, but their cooperative mechanism has not been fully elucidated. Here, we reveal a novel functional interaction between these two components, which is critical for hierarchical substrate recognition and secretion. These findings advance our understanding of the molecular mechanisms underlying bacterial virulence and suggest new potential targets for antimicrobial strategies aimed at disrupting T3SS function.
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Affiliation(s)
- Arely Marcos-Vilchis
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Norma Espinosa
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Adrián F. Alvarez
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - José L. Puente
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Morelos, Mexico
| | - J. Eduardo Soto
- Programa de Ingeniería Genómica, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Morelos, Mexico
| | - Bertha González-Pedrajo
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
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Benyamini P. Beyond Antibiotics: What the Future Holds. Antibiotics (Basel) 2024; 13:919. [PMID: 39452186 PMCID: PMC11504868 DOI: 10.3390/antibiotics13100919] [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: 08/13/2024] [Revised: 09/23/2024] [Accepted: 09/24/2024] [Indexed: 10/26/2024] Open
Abstract
The prevalence of multidrug resistance (MDR) and stagnant drug-development pipelines have led to the rapid rise of hard-to-treat antibiotic-resistant bacterial infections. These infectious diseases are no longer just nosocomial but are also becoming community-acquired. The spread of MDR has reached a crisis level that needs immediate attention. The landmark O'Neill report projects that by 2050, mortality rates associated with MDR bacterial infections will surpass mortality rates associated with individuals afflicted with cancer. Since conventional antimicrobials are no longer very reliable, it is of great importance to investigate different strategies to combat these life-threatening infectious diseases. Here, we provide an overview of recent advances in viable alternative treatment strategies mainly targeting a pathogen's virulence capability rather than viability. Topics include small molecule and immune inhibition of virulence factors, quorum sensing (QS) quenching, inhibition of biofilm development, bacteriophage-mediated therapy, and manipulation of an individual's macroflora to combat MDR bacterial infections.
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Affiliation(s)
- Payam Benyamini
- Department of Health Sciences at Extension, University of California Los Angeles, 1145 Gayley Ave., Los Angeles, CA 90024, USA
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Wimmi S, Balinovic A, Brianceau C, Pintor K, Vielhauer J, Turkowyd B, Helbig C, Fleck M, Langenfeld K, Kahnt J, Glatter T, Endesfelder U, Diepold A. Cytosolic sorting platform complexes shuttle type III secretion system effectors to the injectisome in Yersinia enterocolitica. Nat Microbiol 2024; 9:185-199. [PMID: 38172622 PMCID: PMC10769875 DOI: 10.1038/s41564-023-01545-1] [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: 09/23/2022] [Accepted: 11/06/2023] [Indexed: 01/05/2024]
Abstract
Bacteria use type III secretion injectisomes to inject effector proteins into eukaryotic target cells. Recruitment of effectors to the machinery and the resulting export hierarchy involve the sorting platform. These conserved proteins form pod structures at the cytosolic interface of the injectisome but are also mobile in the cytosol. Photoactivated localization microscopy in Yersinia enterocolitica revealed a direct interaction of the sorting platform proteins SctQ and SctL with effectors in the cytosol of live bacteria. These proteins form larger cytosolic protein complexes involving the ATPase SctN and the membrane connector SctK. The mobility and composition of these mobile pod structures are modulated in the presence of effectors and their chaperones, and upon initiation of secretion, which also increases the number of injectisomes from ~5 to ~18 per bacterium. Our quantitative data support an effector shuttling mechanism, in which sorting platform proteins bind to effectors in the cytosol and deliver the cargo to the export gate at the membrane-bound injectisome.
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Affiliation(s)
- Stephan Wimmi
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Alexander Balinovic
- Department of Systems and Synthetic Microbiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
- SYNMIKRO, Center for Synthetic Microbiology, Marburg, Germany
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA, USA
- Institute for Microbiology and Biotechnology, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
| | - Corentin Brianceau
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Katherine Pintor
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Jan Vielhauer
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Bartosz Turkowyd
- Department of Systems and Synthetic Microbiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
- SYNMIKRO, Center for Synthetic Microbiology, Marburg, Germany
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA, USA
- Institute for Microbiology and Biotechnology, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
| | - Carlos Helbig
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Moritz Fleck
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Katja Langenfeld
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Jörg Kahnt
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
- Mass Spectrometry and Proteomics Facility, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Timo Glatter
- Mass Spectrometry and Proteomics Facility, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Ulrike Endesfelder
- Department of Systems and Synthetic Microbiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany.
- SYNMIKRO, Center for Synthetic Microbiology, Marburg, Germany.
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA, USA.
- Institute for Microbiology and Biotechnology, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany.
| | - Andreas Diepold
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany.
- SYNMIKRO, Center for Synthetic Microbiology, Marburg, Germany.
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Cabezón E, Valenzuela-Gómez F, Arechaga I. Primary architecture and energy requirements of Type III and Type IV secretion systems. Front Cell Infect Microbiol 2023; 13:1255852. [PMID: 38089815 PMCID: PMC10711112 DOI: 10.3389/fcimb.2023.1255852] [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: 07/09/2023] [Accepted: 11/08/2023] [Indexed: 12/18/2023] Open
Abstract
Many pathogens use Type III and Type IV protein secretion systems to secrete virulence factors from the bacterial cytosol into host cells. These systems operate through a one-step mechanism. The secreted substrates (protein or nucleo-protein complexes in the case of Type IV conjugative systems) are guided to the base of the secretion channel, where they are directly delivered into the host cell in an ATP-dependent unfolded state. Despite the numerous disparities between these secretion systems, here we have focused on the structural and functional similarities between both systems. In particular, on the structural similarity shared by one of the main ATPases (EscN and VirD4 in Type III and Type IV secretion systems, respectively). Interestingly, these ATPases also exhibit a structural resemblance to F1-ATPases, which suggests a common mechanism for substrate secretion. The correlation between structure and function of essential components in both systems can provide significant insights into the molecular mechanisms involved. This approach is of great interest in the pursuit of identifying inhibitors that can effectively target these systems.
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Affiliation(s)
- Elena Cabezón
- Departamento de Biología Molecular and Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria- CSIC, Santander, Spain
| | | | - Ignacio Arechaga
- Departamento de Biología Molecular and Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria- CSIC, Santander, Spain
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Yang D, Zhao L, Li Q, Huang L, Qin Y, Wang P, Zhu C, Yan Q. The involvement of the T6SS vgrG gene in the pathogenicity of Pseudomonas plecoglossicida. JOURNAL OF FISH DISEASES 2023; 46:1097-1108. [PMID: 37401135 DOI: 10.1111/jfd.13829] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 06/19/2023] [Accepted: 06/21/2023] [Indexed: 07/05/2023]
Abstract
Pseudomonas plecoglossicida, the causative agent of white spot disease of large yellow croaker, has caused serious economic losses to the aquaculture industry. The type VI secretion system (T6SS) is a significant virulence system widely distributed among Gram-negative bacteria. VgrG, a structural and core component of T6SS, is crucial to the function of T6SS. To explore the biological profiles mediated by vgrG gene and its effects on the pathogenicity of P. plecoglossicida, the vgrG gene deletion (ΔvgrG) strain and complementary (C-ΔvgrG) strain were constructed and the differences in pathogenicity and virulence-related characteristics between different strains were analysed. The results showed that vgrG gene deletion significantly affected the virulence-related characteristics of P. plecoglossicida, including chemotaxis, adhesion, and biofilm formation. In addition, the LD50 of ΔvgrG strain was nearly 50-fold higher than that of the NZBD9 strain. Transcriptome data analysis suggested that the vgrG gene may affect the virulence of P. plecoglossicida by regulating the quorum sensing pathway to inhibit the secretion of virulence factors and affect biofilm formation. Besides, deletion of the vgrG gene may reduce bacterial pathogenicity by affecting bacterial signal transduction processes and the ability to adapt to chemotactic substances.
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Affiliation(s)
- Dou Yang
- Fisheries College, Jimei University, Xiamen, China
| | - Lingmin Zhao
- Fisheries College, Jimei University, Xiamen, China
| | - Qi Li
- Fisheries College, Jimei University, Xiamen, China
| | - Lixing Huang
- Fisheries College, Jimei University, Xiamen, China
| | - Yingxue Qin
- Fisheries College, Jimei University, Xiamen, China
| | - Pan Wang
- Key Laboratory of Aquatic Functional Feed and Environmental Regulation of Fujian Province, Fujian Dabeinong Aquatic Sci. & Tech. Co., Ltd, Zhangzhou, China
| | - Chuanzhong Zhu
- Key Laboratory of Aquatic Functional Feed and Environmental Regulation of Fujian Province, Fujian Dabeinong Aquatic Sci. & Tech. Co., Ltd, Zhangzhou, China
| | - Qingpi Yan
- Fisheries College, Jimei University, Xiamen, China
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Soto JE, Lara-Tejero M. The sorting platform in the type III secretion pathway: From assembly to function. Bioessays 2023; 45:e2300078. [PMID: 37329195 DOI: 10.1002/bies.202300078] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 06/05/2023] [Accepted: 06/07/2023] [Indexed: 06/18/2023]
Abstract
The type III secretion system (T3SS) is a specialized nanomachine that enables bacteria to secrete proteins in a specific order and directly deliver a specific set of them, collectively known as effectors, into eukaryotic organisms. The core structure of the T3SS is a syringe-like apparatus composed of multiple building blocks, including both membrane-associated and soluble proteins. The cytosolic components organize together in a chamber-like structure known as the sorting platform (SP), responsible for recruiting, sorting, and initiating the substrates destined to engage this secretion pathway. In this article, we provide an overview of recent findings on the SP's structure and function, with a particular focus on its assembly pathway. Furthermore, we discuss the molecular mechanisms behind the recruitment and hierarchical sorting of substrates by this cytosolic complex. Overall, the T3SS is a highly specialized and complex system that requires precise coordination to function properly. A deeper understanding of how the SP orchestrates T3S could enhance our comprehension of this complex nanomachine, which is central to the host-pathogen interface, and could aid in the development of novel strategies to fight bacterial infections.
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Affiliation(s)
- Jose Eduardo Soto
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, USA
| | - María Lara-Tejero
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, USA
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