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Geller AM, Shalom M, Zlotkin D, Blum N, Levy A. Identification of type VI secretion system effector-immunity pairs using structural bioinformatics. Mol Syst Biol 2024; 20:702-718. [PMID: 38658795 PMCID: PMC11148199 DOI: 10.1038/s44320-024-00035-8] [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: 01/02/2024] [Revised: 03/24/2024] [Accepted: 04/09/2024] [Indexed: 04/26/2024] Open
Abstract
The type VI secretion system (T6SS) is an important mediator of microbe-microbe and microbe-host interactions. Gram-negative bacteria use the T6SS to inject T6SS effectors (T6Es), which are usually proteins with toxic activity, into neighboring cells. Antibacterial effectors have cognate immunity proteins that neutralize self-intoxication. Here, we applied novel structural bioinformatic tools to perform systematic discovery and functional annotation of T6Es and their cognate immunity proteins from a dataset of 17,920 T6SS-encoding bacterial genomes. Using structural clustering, we identified 517 putative T6E families, outperforming sequence-based clustering. We developed a logistic regression model to reliably quantify protein-protein interaction of new T6E-immunity pairs, yielding candidate immunity proteins for 231 out of the 517 T6E families. We used sensitive structure-based annotation which yielded functional annotations for 51% of the T6E families, again outperforming sequence-based annotation. Next, we validated four novel T6E-immunity pairs using basic experiments in E. coli. In particular, we showed that the Pfam domain DUF3289 is a homolog of Colicin M and that DUF943 acts as its cognate immunity protein. Furthermore, we discovered a novel T6E that is a structural homolog of SleB, a lytic transglycosylase, and identified a specific glutamate that acts as its putative catalytic residue. Overall, this study applies novel structural bioinformatic tools to T6E-immunity pair discovery, and provides an extensive database of annotated T6E-immunity pairs.
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Affiliation(s)
- Alexander M Geller
- Department of Plant Pathology and Microbiology, The Institute of Environmental Science, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Maor Shalom
- Department of Plant Pathology and Microbiology, The Institute of Environmental Science, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - David Zlotkin
- Department of Plant Pathology and Microbiology, The Institute of Environmental Science, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Noam Blum
- Department of Plant Pathology and Microbiology, The Institute of Environmental Science, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Asaf Levy
- Department of Plant Pathology and Microbiology, The Institute of Environmental Science, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel.
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2
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Jiang X, Li H, Ma J, Li H, Ma X, Tang Y, Li J, Chi X, Deng Y, Zeng S, Liu Z. Role of Type VI secretion system in pathogenic remodeling of host gut microbiota during Aeromonas veronii infection. THE ISME JOURNAL 2024; 18:wrae053. [PMID: 38531781 PMCID: PMC11014884 DOI: 10.1093/ismejo/wrae053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 01/31/2024] [Accepted: 03/21/2024] [Indexed: 03/28/2024]
Abstract
Intestinal microbial disturbance is a direct cause of host disease. The bacterial Type VI secretion system (T6SS) often plays a crucial role in the fitness of pathogenic bacteria by delivering toxic effectors into target cells. However, its impact on the gut microbiota and host pathogenesis is poorly understood. To address this question, we characterized a new T6SS in the pathogenic Aeromonas veronii C4. First, we validated the secretion function of the core machinery of A. veronii C4 T6SS. Second, we found that the pathogenesis and colonization of A. veronii C4 is largely dependent on its T6SS. The effector secretion activity of A. veronii C4 T6SS not only provides an advantage in competition among bacteria in vitro, but also contributes to occupation of an ecological niche in the nutritionally deficient and anaerobic environment of the host intestine. Metagenomic analysis showed that the T6SS directly inhibits or eliminates symbiotic strains from the intestine, resulting in dysregulated gut microbiome homeostasis. In addition, we identified three unknown effectors, Tse1, Tse2, and Tse3, in the T6SS, which contribute to T6SS-mediated bacterial competition and pathogenesis by impairing targeted cell integrity. Our findings highlight that T6SS can remodel the host gut microbiota by intricate interplay between T6SS-mediated bacterial competition and altered host immune responses, which synergistically promote pathogenesis of A. veronii C4. Therefore, this newly characterized T6SS could represent a general interaction mechanism between the host and pathogen, and may offer a potential therapeutic target for controlling bacterial pathogens.
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Affiliation(s)
- Xiaoli Jiang
- School of Life and Health Sciences, Hainan University, Haikou 570228, China
| | - Hanzeng Li
- School of Life and Health Sciences, Hainan University, Haikou 570228, China
| | - Jiayue Ma
- School of Life and Health Sciences, Hainan University, Haikou 570228, China
| | - Hong Li
- School of Life and Health Sciences, Hainan University, Haikou 570228, China
| | - Xiang Ma
- School of Life and Health Sciences, Hainan University, Haikou 570228, China
| | - Yanqiong Tang
- School of Life and Health Sciences, Hainan University, Haikou 570228, China
| | - Juanjuan Li
- School of Life and Health Sciences, Hainan University, Haikou 570228, China
| | - Xue Chi
- School of Life and Health Sciences, Hainan University, Haikou 570228, China
| | - Yong Deng
- Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Sheng Zeng
- Susheng Biotech (Hainan) Co., Ltd, Haikou 570228, China
| | - Zhu Liu
- School of Life and Health Sciences, Hainan University, Haikou 570228, China
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3
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Garin T, Brin C, Préveaux A, Brault A, Briand M, Simonin M, Barret M, Journet L, Sarniguet A. The type VI secretion system of Stenotrophomonas rhizophila CFBP13503 limits the transmission of Xanthomonas campestris pv. campestris 8004 from radish seeds to seedlings. MOLECULAR PLANT PATHOLOGY 2024; 25:e13412. [PMID: 38279854 PMCID: PMC10777753 DOI: 10.1111/mpp.13412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 10/20/2023] [Accepted: 11/27/2023] [Indexed: 01/29/2024]
Abstract
Stenotrophomonas rhizophila CFBP13503 is a seedborne commensal bacterial strain, which is efficiently transmitted to seedlings and can outcompete the phytopathogenic bacterium Xanthomonas campestris pv. campestris (Xcc8004). The type VI secretion system (T6SS), an interference contact-dependent mechanism, is a critical component of interbacterial competition. The involvement of the T6SS of S. rhizophila CFBP13503 in the inhibition of Xcc8004 growth and seed-to-seedling transmission was assessed. The T6SS cluster of S. rhizophila CFBP13503 and nine putative effectors were identified. Deletion of two T6SS structural genes, hcp and tssB, abolished the competitive advantage of S. rhizophila against Xcc8004 in vitro. The population sizes of these two bacterial species were monitored in seedlings after inoculation of radish seeds with mixtures of Xcc8004 and either S. rhizophila wild-type (wt) strain or isogenic hcp mutant. A significant decrease in the population size of Xcc8004 was observed during confrontation with the S. rhizophila wt in comparison with T6SS-deletion mutants in germinated seeds and seedlings. We found that the T6SS distribution among 835 genomes of the Stenotrophomonas genus is scarce. In contrast, in all available S. rhizophila genomes, T6SS clusters are widespread and mainly belong to the T6SS group i4. In conclusion, the T6SS of S. rhizophila CFBP13503 is involved in the antibiosis against Xcc8004 and reduces seedling transmission of Xcc8004 in radish. The distribution of this T6SS cluster in the S. rhizophila complex could make it possible to exploit these strains as biocontrol agents against X. campestris pv. campestris.
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Affiliation(s)
- Tiffany Garin
- Univ Angers, Institut Agro, INRAE, IRHS, SFR QUASAVAngersFrance
| | - Chrystelle Brin
- Univ Angers, Institut Agro, INRAE, IRHS, SFR QUASAVAngersFrance
| | - Anne Préveaux
- Univ Angers, Institut Agro, INRAE, IRHS, SFR QUASAVAngersFrance
| | - Agathe Brault
- Univ Angers, Institut Agro, INRAE, IRHS, SFR QUASAVAngersFrance
| | - Martial Briand
- Univ Angers, Institut Agro, INRAE, IRHS, SFR QUASAVAngersFrance
| | - Marie Simonin
- Univ Angers, Institut Agro, INRAE, IRHS, SFR QUASAVAngersFrance
| | - Matthieu Barret
- Univ Angers, Institut Agro, INRAE, IRHS, SFR QUASAVAngersFrance
| | - Laure Journet
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, Institut de Microbiologie, Bioénergies et Biotechnologie, Institut de Microbiologie de la MéditerranéeAix‐Marseille Université‐CNRS, UMR 7255MarseilleFrance
| | - Alain Sarniguet
- Univ Angers, Institut Agro, INRAE, IRHS, SFR QUASAVAngersFrance
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Beauvois SG, Flaugnatti N, Ilbert M, Boyer M, Gavello-Fernandez E, Fronzes R, Jurėnas D, Journet L. The tip protein PAAR is required for the function of the type VI secretion system. Microbiol Spectr 2023; 11:e0147823. [PMID: 37800964 PMCID: PMC10715212 DOI: 10.1128/spectrum.01478-23] [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: 04/07/2023] [Accepted: 08/09/2023] [Indexed: 10/07/2023] Open
Abstract
IMPORTANCE The type VI secretion system (T6SS) is a bacterial contractile injection system involved in bacterial competition by the delivery of antibacterial toxins. The T6SS consists of an envelope-spanning complex that recruits the baseplate, allowing the polymerization of a contractile tail structure. The tail is a tube wrapped by a sheath and topped by the tip of the system, the VgrG spike/PAAR complex. Effectors loaded onto the puncturing tip or into the tube are propelled in the target cells upon sheath contraction. The PAAR protein tips and sharpens the VgrG spike. However, the importance and the function of this protein remain unclear. Here, we provide evidence for association of PAAR at the tip of the VgrG spike. We also found that the PAAR protein is a T6SS critical component required for baseplate and sheath assembly.
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Affiliation(s)
- Solène G. Beauvois
- Laboratoire d’Ingénierie des Systèmes Macromoléculaires, Institut de Microbiologie, Bioénergies et Biotechnologie, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université - CNRS UMR7255, Marseille, France
| | - Nicolas Flaugnatti
- Laboratoire d’Ingénierie des Systèmes Macromoléculaires, Institut de Microbiologie, Bioénergies et Biotechnologie, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université - CNRS UMR7255, Marseille, France
| | - Marianne Ilbert
- Laboratoire de Bioénergétique et Ingénierie des Protéines, Institut de Microbiologie, Bioénergies et Biotechnologie, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université - CNRS UMR7281, Marseille, France
| | - Marie Boyer
- Laboratoire d’Ingénierie des Systèmes Macromoléculaires, Institut de Microbiologie, Bioénergies et Biotechnologie, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université - CNRS UMR7255, Marseille, France
| | - Esther Gavello-Fernandez
- Institut Européen de Chimie et Biologie, University of Bordeaux, Pessac, France
- CNRS UMR 5234 Microbiologie Fondamentale et Pathogénicité, Bordeaux, France
| | - Rémi Fronzes
- Institut Européen de Chimie et Biologie, University of Bordeaux, Pessac, France
- CNRS UMR 5234 Microbiologie Fondamentale et Pathogénicité, Bordeaux, France
| | - Dukas Jurėnas
- Laboratoire d’Ingénierie des Systèmes Macromoléculaires, Institut de Microbiologie, Bioénergies et Biotechnologie, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université - CNRS UMR7255, Marseille, France
| | - Laure Journet
- Laboratoire d’Ingénierie des Systèmes Macromoléculaires, Institut de Microbiologie, Bioénergies et Biotechnologie, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université - CNRS UMR7255, Marseille, France
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5
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Wang C, Chen M, Shao Y, Jiang M, Li Q, Chen L, Wu Y, Cen S, Waterfield NR, Yang J, Yang G. Genome wide analysis revealed conserved domains involved in the effector discrimination of bacterial type VI secretion system. Commun Biol 2023; 6:1195. [PMID: 38001377 PMCID: PMC10673891 DOI: 10.1038/s42003-023-05580-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 11/13/2023] [Indexed: 11/26/2023] Open
Abstract
Type VI secretion systems (T6SSs) deliver effectors into target cells. Besides structural and effector proteins, many other proteins, such as adaptors, co-effectors and accessory proteins, are involved in this process. MIX domains can assist in the delivery of T6SS effectors when encoded as a stand-alone gene or fused at the N-terminal of the effector. However, whether there are other conserved domains exhibiting similar encoding forms to MIX in T6SS remains obscure. Here, we scanned publicly available bacterial genomes and established a database which include 130,825 T6SS vgrG loci from 45,041 bacterial genomes. Based on this database, we revealed six domain families encoded within vgrG loci, which are either fused at the C-terminus of VgrG/N-terminus of T6SS toxin or encoded by an independent gene. Among them, DUF2345 was further validated and shown to be indispensable for the T6SS effector delivery and LysM was confirmed to assist the interaction between VgrG and the corresponding effector. Together, our results implied that these widely distributed domain families with similar genetic configurations may be required for the T6SS effector recruitment process.
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Affiliation(s)
- Caihong Wang
- Beijing Institute of Tropical Medicine, Beijing Friendship Hospital, Capital Medical University, Beijing, 100050, China
| | - Mingxing Chen
- NHC Key Laboratory of Systems Biology of Pathogens, National Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 102629, China
| | - Yuhan Shao
- Beijing Institute of Tropical Medicine, Beijing Friendship Hospital, Capital Medical University, Beijing, 100050, China
| | - Mengyuan Jiang
- Beijing Institute of Tropical Medicine, Beijing Friendship Hospital, Capital Medical University, Beijing, 100050, China
| | - Quanjie Li
- Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100050, China
| | - Lihong Chen
- NHC Key Laboratory of Systems Biology of Pathogens, National Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 102629, China
| | - Yun Wu
- Beijing Institute of Tropical Medicine, Beijing Friendship Hospital, Capital Medical University, Beijing, 100050, China
| | - Shan Cen
- Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100050, China
- CAMS Key Laboratory of Antiviral Drug Research, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, 100730, China
| | | | - Jian Yang
- NHC Key Laboratory of Systems Biology of Pathogens, National Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 102629, China.
| | - Guowei Yang
- Beijing Institute of Tropical Medicine, Beijing Friendship Hospital, Capital Medical University, Beijing, 100050, China.
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6
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Meir A, Macé K, Vegunta Y, Williams SM, Waksman G. Substrate recruitment mechanism by gram-negative type III, IV, and VI bacterial injectisomes. Trends Microbiol 2023; 31:916-932. [PMID: 37085348 DOI: 10.1016/j.tim.2023.03.005] [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: 10/28/2022] [Revised: 03/09/2023] [Accepted: 03/13/2023] [Indexed: 04/23/2023]
Abstract
Bacteria use a wide arsenal of macromolecular substrates (DNA and proteins) to interact with or infect prokaryotic and eukaryotic cells. To do so, they utilize substrate-injecting secretion systems or injectisomes. However, prior to secretion, substrates must be recruited to specialized recruitment platforms and then handed over to the secretion apparatus for secretion. In this review, we provide an update on recent advances in substrate recruitment and delivery by gram-negative bacterial recruitment platforms associated with Type III, IV, and VI secretion systems.
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Affiliation(s)
- Amit Meir
- Institute of Structural and Molecular Biology, Birkbeck and UCL, Malet Street, London WC1E 7HX, UK; Current address: MRC Centre for Virus Research, School of Infection and Immunity, University of Glasgow, Glasgow, UK.
| | - Kévin Macé
- Institute of Structural and Molecular Biology, Birkbeck and UCL, Malet Street, London WC1E 7HX, UK
| | - Yogesh Vegunta
- Institute of Structural and Molecular Biology, Birkbeck and UCL, Malet Street, London WC1E 7HX, UK
| | - Sunanda M Williams
- Institute of Structural and Molecular Biology, Birkbeck and UCL, Malet Street, London WC1E 7HX, UK
| | - Gabriel Waksman
- Institute of Structural and Molecular Biology, Birkbeck and UCL, Malet Street, London WC1E 7HX, UK; Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK.
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7
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Kanarek K, Fridman CM, Bosis E, Salomon D. The RIX domain defines a class of polymorphic T6SS effectors and secreted adaptors. Nat Commun 2023; 14:4983. [PMID: 37591831 PMCID: PMC10435454 DOI: 10.1038/s41467-023-40659-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 08/01/2023] [Indexed: 08/19/2023] Open
Abstract
Bacteria use the type VI secretion system (T6SS) to deliver toxic effectors into bacterial or eukaryotic cells during interbacterial competition, host colonization, or when resisting predation. Identifying effectors is a challenging task, as they lack canonical secretion signals or universally conserved domains. Here, we identify a protein domain, RIX, that defines a class of polymorphic T6SS cargo effectors. RIX is widespread in the Vibrionaceae family and is located at N-termini of proteins containing diverse antibacterial and anti-eukaryotic toxic domains. We demonstrate that RIX-containing proteins are delivered via T6SS into neighboring cells and that RIX is necessary and sufficient for T6SS-mediated secretion. In addition, RIX-containing proteins can enable the T6SS-mediated delivery of other cargo effectors by a previously undescribed mechanism. The identification of RIX-containing proteins significantly enlarges the repertoire of known T6SS effectors, especially those with anti-eukaryotic activities. Furthermore, our findings also suggest that T6SSs may play an underappreciated role in the interactions between vibrios and eukaryotes.
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Affiliation(s)
- Katarzyna Kanarek
- Department of Clinical Microbiology and Immunology, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Chaya Mushka Fridman
- Department of Clinical Microbiology and Immunology, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Eran Bosis
- Department of Biotechnology Engineering, Braude College of Engineering, Karmiel, Israel.
| | - Dor Salomon
- Department of Clinical Microbiology and Immunology, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
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8
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He W, Wu K, Ouyang Z, Bai Y, Luo W, Wu D, An H, Guo Y, Jiao M, Qin Q, Zhang J, Wu Y, She J, Hwang PM, Zheng F, Zhu L, Wen Y. Structure and assembly of type VI secretion system cargo delivery vehicle. Cell Rep 2023; 42:112781. [PMID: 37421630 DOI: 10.1016/j.celrep.2023.112781] [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: 10/23/2022] [Revised: 05/06/2023] [Accepted: 06/25/2023] [Indexed: 07/10/2023] Open
Abstract
Type VI secretion system is widely used in Gram-negative bacteria for injecting toxic effectors into neighboring prokaryotic or eukaryotic cells. Various effectors can be loaded onto the T6SS delivery tube via its core components: Hcp, VgrG, or PAAR. Here, we report 2.8-Å resolution cryo-EM structure of intact T6SS Hcp5-VgrG-PAAR cargo delivery system and crystal structure of unbound Hcp5 from B. fragilis NCTC 9343. Loading of Hcp5 hexameric ring onto VgrG causes expansion of its inner cavity and external surface, explaining how structural changes could be propagated to regulate co-polymerization and surrounding contractile sheath. High-affinity binding between Hcp and VgrG causes entropically unfavorable structuring of long loops. Furthermore, interactions between VgrG trimer and Hcp hexamer are asymmetric, with three of the six Hcp monomers exhibiting a major loop flip. Our study provides insights into the assembly, loading, and firing of T6SS nanomachine that contributes to bacterial inter-species competition and host interactions.
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Affiliation(s)
- Wenbo He
- Center for Microbiome Research of Med-X Institute, Shaanxi Provincial Key Laboratory of Sepsis in Critical Care Medicine, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, China
| | - Ke Wu
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Zhenlin Ouyang
- Center for Microbiome Research of Med-X Institute, Shaanxi Provincial Key Laboratory of Sepsis in Critical Care Medicine, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, China
| | - Yixin Bai
- Center for Microbiome Research of Med-X Institute, Shaanxi Provincial Key Laboratory of Sepsis in Critical Care Medicine, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, China
| | - Wen Luo
- Department of Oncology, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Di Wu
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Hao An
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Yucheng Guo
- The Key Laboratory of Environment and Genes Related to Disease of Ministry of Education Health Science Center, Xi'an Jiaotong University, Xi'an 710061, China
| | - Min Jiao
- Center for Microbiome Research of Med-X Institute, Shaanxi Provincial Key Laboratory of Sepsis in Critical Care Medicine, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, China
| | - Qian Qin
- Center for Microbiome Research of Med-X Institute, Shaanxi Provincial Key Laboratory of Sepsis in Critical Care Medicine, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, China
| | - Jiaxin Zhang
- The Key Laboratory of Environment and Genes Related to Disease of Ministry of Education Health Science Center, Xi'an Jiaotong University, Xi'an 710061, China
| | - Yi Wu
- The Key Laboratory of Environment and Genes Related to Disease of Ministry of Education Health Science Center, Xi'an Jiaotong University, Xi'an 710061, China
| | - Junjun She
- Center for Microbiome Research of Med-X Institute, Shaanxi Provincial Key Laboratory of Sepsis in Critical Care Medicine, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, China
| | - Peter M Hwang
- Department of Biochemistry, Faculty of Medicine & Dentistry, Edmonton, AB T6G 2R3, Canada
| | - Fang Zheng
- The Key Laboratory of Environment and Genes Related to Disease of Ministry of Education Health Science Center, Xi'an Jiaotong University, Xi'an 710061, China
| | - Li Zhu
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China; Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Electron Microscopy Centre of Lanzhou University, Lanzhou University, Lanzhou 730000, China.
| | - Yurong Wen
- Center for Microbiome Research of Med-X Institute, Shaanxi Provincial Key Laboratory of Sepsis in Critical Care Medicine, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, China; The Key Laboratory of Environment and Genes Related to Disease of Ministry of Education Health Science Center, Xi'an Jiaotong University, Xi'an 710061, China.
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9
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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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10
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Calder A, Snyder LAS. Diversity of the type VI secretion systems in the Neisseria spp. Microb Genom 2023; 9. [PMID: 37052605 DOI: 10.1099/mgen.0.000986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/14/2023] Open
Abstract
Complete Type VI Secretion Systems were identified in the genome sequence data of Neisseria subflava isolates sourced from throat swabs of human volunteers. The previous report was the first to describe two complete Type VI Secretion Systems in these isolates, both of which were distinct in terms of their gene organization and sequence homology. Since publication of the first report, Type VI Secretion System subtypes have been identified in Neisseria spp. The characteristics of each type in N. subflava are further investigated here and in the context of the other Neisseria spp., including identification of the lineages containing the different types and subtypes. Type VI Secretion Systems use VgrG for delivery of toxin effector proteins; several copies of vgrG and associated effector / immunity pairs are present in Neisseria spp. Based on sequence similarity between strains and species, these core Type VI Secretion System genes, vgrG, and effector / immunity genes may diversify via horizontal gene transfer, an instrument for gene acquisition and repair in Neisseria spp.
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Affiliation(s)
- Alan Calder
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Penrhyn Road, Kingston upon Thames, KT1 2EE, UK
| | - Lori A S Snyder
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Penrhyn Road, Kingston upon Thames, KT1 2EE, UK
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11
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Activity and Crystal Structure of the Adherent-Invasive Escherichia coli Tle3/Tli3 T6SS Effector/Immunity Complex Determined Using an AlphaFold2 Predicted Model. Int J Mol Sci 2023; 24:ijms24021740. [PMID: 36675258 PMCID: PMC9860674 DOI: 10.3390/ijms24021740] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 01/11/2023] [Accepted: 01/13/2023] [Indexed: 01/19/2023] Open
Abstract
The type VI secretion system (T6SS) delivers enzymatic effectors into target cells to destroy them. Cells of the same strain protect themselves against effectors with immunity proteins that specifically inhibit effectors. Here, we report the identification and characterization of a Tle3 phospholipase effector and its cognate immunity protein Tli3-an outer membrane lipoprotein from adherent-invasive Escherichia coli (AIEC). Enzymatic assays demonstrate that purified Tle3AIEC has a phospholipase A1, and not A2, activity and that its toxicity is neutralized by the cognate immunity protein Tli3AIEC. Tli3AIEC binds Tle3 in a 1:1 stoichiometric ratio. Tle3AIEC, Tli3AIEC and the Tle3AIEC-Tli3AIEC complex were purified and subjected to crystallization. The Tle3AIEC-Tli3AIEC complex structure could not be solved by SeMet phasing, but only by molecular replacement when using an AlphaFold2 prediction model. Tle3AIEC exhibits an α/β-hydrolase fold decorated by two protruding segments, including a N-terminus loop. Tli3AIEC displays a new fold of three stacked β-sheets and a protruding loop that inserts in Tle3AIECcatalytic crevice. We showed, experimentally, that Tle3AIEC interacts with the VgrG AIEC cargo protein and AlphaFold2 prediction of the VgrGAIEC-Tle3AIEC complex reveals a strong interaction between the VgrGAIEC C-terminus adaptor and Tle3AIEC N-terminal loop.
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12
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Guzmán-Herrador DL, Fernández-Gómez A, Llosa M. Recruitment of heterologous substrates by bacterial secretion systems for transkingdom translocation. Front Cell Infect Microbiol 2023; 13:1146000. [PMID: 36949816 PMCID: PMC10025392 DOI: 10.3389/fcimb.2023.1146000] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 02/22/2023] [Indexed: 03/08/2023] Open
Abstract
Bacterial secretion systems mediate the selective exchange of macromolecules between bacteria and their environment, playing a pivotal role in processes such as horizontal gene transfer or virulence. Among the different families of secretion systems, Type III, IV and VI (T3SS, T4SS and T6SS) share the ability to inject their substrates into human cells, opening up the possibility of using them as customized injectors. For this to happen, it is necessary to understand how substrates are recruited and to be able to engineer secretion signals, so that the transmembrane machineries can recognize and translocate the desired substrates in place of their own. Other factors, such as recruiting proteins, chaperones, and the degree of unfolding required to cross through the secretion channel, may also affect transport. Advances in the knowledge of the secretion mechanism have allowed heterologous substrate engineering to accomplish translocation by T3SS, and to a lesser extent, T4SS and T6SS into human cells. In the case of T4SS, transport of nucleoprotein complexes adds a bonus to its biotechnological potential. Here, we review the current knowledge on substrate recognition by these secretion systems, the many examples of heterologous substrate translocation by engineering of secretion signals, and the current and future biotechnological and biomedical applications derived from this approach.
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13
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Huang Y, Han Y, Li Z, Li X, Li Z, Liu P, Liu X, Cheng Q, Fan F, Kan B, Liang W. TssI2-TsiI2 of Vibrio fluvialis VflT6SS2 delivers pesticin domain-containing periplasmic toxin and cognate immunity that modulates bacterial competitiveness. Gut Microbes 2022; 14:2136460. [PMID: 36288406 PMCID: PMC9620997 DOI: 10.1080/19490976.2022.2136460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Vibrio fluvialis is a halophilic Gram-negative bacterium regarded as an emerging unusual enteric pathogen of increasing public health concern. Our previous work has identified two type VI secretion systems (T6SSs) in V. fluvialis, VflT6SS1, and VflT6SS2, and the latter is functional in mediating interbacterial competitiveness. However, its antibacterial effectors remain to be clarified. In this work, we focused on a new potential effector/immunity pair TssI2/TsiI2. Bioinformatics analysis revealed that the C-terminal domain of TssI2 belongs to a widespread family of pesticin, and its antibacterial toxicity and corresponding protection by TsiI2 were proved via bacterial killing assays, and their action sites were localized to the periplasm of bacterial cells. The interaction of TssI2 and TsiI2 was demonstrated by the bacterial adenylate cyclase two-hybrid, protein pull-down and isothermal titration calorimetry assays. Site-directed mutagenesis demonstrated that, in addition to Glu-844, Thr-863, and Asp-869, which correspond to three reported residues in pesticin of Yersinia pestis, additional residues including Phe-837, Gly-845, Tyr-851, Gly-867, Gln-963, Trp-975, and Arg-1000 were also proved to be crucial to the bactericidal activity of TssI2. Muramidase/lysozyme-related peptidoglycan (PG) hydrolase activities of TssI2 and its variants were validated with permeabilized Escherichia coli cells and purified PG substrate. Based on sequence homologies at C-terminals in various V. fluvialis isolates, TssI2 was subdivided into five clusters (12-22% identity among them), and the antibacterial activities of representative effectors from other four Clusters were also confirmed through periplasmic over-expression in E. coli host. Two selected cognate immunities were proved to confer protection against the toxicities of their effectors. Additionally, TsiI2, which belongs to Cluster I, exhibited cross-protection to effector from Cluster V. Together, current findings expand our knowledge of the diversity and consistency of evolved VgrG effectors in V. fluvialis and on how VflT6SS2 mediates a competitive advantage to gain a better survival.
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Affiliation(s)
- Yuanming Huang
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Yu Han
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Zhenpeng Li
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Xiaorui Li
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Zhe Li
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Ping Liu
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Xiaoshu Liu
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Qian Cheng
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Fenxia Fan
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Biao Kan
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China,CONTACT Biao Kan
| | - Weili Liang
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China,Weili Liang State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
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14
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Lorente Cobo N, Sibinelli-Sousa S, Biboy J, Vollmer W, Bayer-Santos E, Prehna G. Molecular characterization of the type VI secretion system effector Tlde1a reveals a structurally altered LD-transpeptidase fold. J Biol Chem 2022; 298:102556. [PMID: 36183829 PMCID: PMC9638812 DOI: 10.1016/j.jbc.2022.102556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 09/26/2022] [Accepted: 09/27/2022] [Indexed: 12/01/2022] Open
Abstract
The type VI secretion system (T6SS) is a molecular machine that Gram-negative bacteria have adapted for multiple functions, including interbacterial competition. Bacteria use the T6SS to deliver protein effectors into adjacent cells to kill rivals and establish niche dominance. Central to T6SS-mediated bacterial competition is an arms race to acquire diverse effectors to attack and neutralize target cells. The peptidoglycan has a central role in bacterial cell physiology, and effectors that biochemically modify peptidoglycan structure effectively induce cell death. One such T6SS effector is Tlde1a from Salmonella Typhimurium. Tlde1a functions as an LD-carboxypeptidase to cleave tetrapeptide stems and as an LD-transpeptidase to exchange the terminal D-alanine of a tetrapeptide stem with a noncanonical D-amino acid. To understand how Tlde1a exhibits toxicity at the molecular level, we determined the X-ray crystal structure of Tlde1a alone and in complex with D-amino acids. Our structural data revealed that Tlde1a possesses a unique LD-transpeptidase fold consisting of a dual pocket active site with a capping subdomain. This includes an exchange pocket to bind a D-amino acid for exchange and a catalytic pocket to position the D-alanine of a tetrapeptide stem for cleavage. Our toxicity assays in Escherichia coli and in vitro peptidoglycan biochemical assays with Tlde1a variants correlate Tlde1a molecular features directly to its biochemical functions. We observe that the LD-carboxypeptidase and LD-transpeptidase activities of Tlde1a are both structurally and functionally linked. Overall, our data highlight how an LD-transpeptidase fold has been structurally altered to create a toxic effector in the T6SS arms race.
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Affiliation(s)
- Neil Lorente Cobo
- Department of Microbiology, University of Manitoba, Winnipeg, Canada
| | - Stephanie Sibinelli-Sousa
- Department of Microbiology, Biomedical Sciences Institute, University of São Paulo, São Paulo, Brazil
| | - Jacob Biboy
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Waldemar Vollmer
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Ethel Bayer-Santos
- Department of Microbiology, Biomedical Sciences Institute, University of São Paulo, São Paulo, Brazil
| | - Gerd Prehna
- Department of Microbiology, University of Manitoba, Winnipeg, Canada.
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15
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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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16
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Dar Y, Jana B, Bosis E, Salomon D. A binary effector module secreted by a type VI secretion system. EMBO Rep 2022; 23:e53981. [PMID: 34752000 PMCID: PMC8728615 DOI: 10.15252/embr.202153981] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 10/20/2021] [Accepted: 10/22/2021] [Indexed: 01/22/2023] Open
Abstract
Gram-negative bacteria use type VI secretion systems (T6SSs) to deliver toxic effector proteins into neighboring cells. Cargo effectors are secreted by binding noncovalently to the T6SS apparatus. Occasionally, effector secretion is assisted by an adaptor protein, although the adaptor itself is not secreted. Here, we report a new T6SS secretion mechanism, in which an effector and a co-effector are secreted together. Specifically, we identify a novel periplasm-targeting effector that is secreted together with its co-effector, which contains a MIX (marker for type sIX effector) domain previously reported only in polymorphic toxins. The effector and co-effector directly interact, and they are dependent on each other for secretion. We term this new secretion mechanism "a binary effector module," and we show that it is widely distributed in marine bacteria.
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Affiliation(s)
- Yasmin Dar
- Department of Clinical Microbiology and ImmunologySackler Faculty of MedicineTel Aviv UniversityTel AvivIsrael
| | - Biswanath Jana
- Department of Clinical Microbiology and ImmunologySackler Faculty of MedicineTel Aviv UniversityTel AvivIsrael
| | - Eran Bosis
- Department of Biotechnology EngineeringORT Braude College of EngineeringKarmielIsrael
| | - Dor Salomon
- Department of Clinical Microbiology and ImmunologySackler Faculty of MedicineTel Aviv UniversityTel AvivIsrael
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17
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Liang X, Pei TT, Li H, Zheng HY, Luo H, Cui Y, Tang MX, Zhao YJ, Xu P, Dong T. VgrG-dependent effectors and chaperones modulate the assembly of the type VI secretion system. PLoS Pathog 2021; 17:e1010116. [PMID: 34852023 PMCID: PMC8668125 DOI: 10.1371/journal.ppat.1010116] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 12/13/2021] [Accepted: 11/15/2021] [Indexed: 11/19/2022] Open
Abstract
The type VI secretion system (T6SS) is a spear-like nanomachine found in gram-negative pathogens for delivery of toxic effectors to neighboring bacterial and host cells. Its assembly requires a tip spike complex consisting of a VgrG-trimer, a PAAR protein, and the interacting effectors. However, how the spike controls T6SS assembly remains elusive. Here we investigated the role of three VgrG-effector pairs in Aeromonas dhakensis strain SSU, a clinical isolate with a constitutively active T6SS. By swapping VgrG tail sequences, we demonstrate that the C-terminal ~30 amino-acid tail dictates effector specificity. Double deletion of vgrG1&2 genes (VgrG3+) abolished T6SS secretion, which can be rescued by ectopically expressing chimeric VgrG3 with a VgrG1/2-tail but not the wild type VgrG3. In addition, deletion of effector-specific chaperones also severely impaired T6SS secretion, despite the presence of intact VgrG and effector proteins, in both SSU and Vibrio cholerae V52. We further show that SSU could deliver a V. cholerae effector VasX when expressing a plasmid-borne chimeric VgrG with VasX-specific VgrG tail and chaperone sequences. Pull-down analyses show that two SSU effectors, TseP and TseC, could interact with their cognate VgrGs, the baseplate protein TssK, and the key assembly chaperone TssA. Effectors TseL and VasX could interact with TssF, TssK and TssA in V. cholerae. Collectively, we demonstrate that chimeric VgrG-effector pairs could bypass the requirement of heterologous VgrG complex and propose that effector-stuffing inside the baseplate complex, facilitated by chaperones and the interaction with structural proteins, serves as a crucial structural determinant for T6SS assembly. Effectors of bacterial secretion systems are generally considered as secreted proteins for interspecies interactions rather than components of the secretion apparatus. Our results reveal the complex interactions of effectors, chaperones, and structural proteins are crucial for T6SS assembly, suggesting an integral role of effectors as parts of the apparatus and distinctive from other secretion systems.
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Affiliation(s)
- Xiaoye Liang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Tong-Tong Pei
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Hao Li
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Hao-Yu Zheng
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Han Luo
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Yang Cui
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Ming-Xuan Tang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Ya-Jie Zhao
- Department of Immunology and Microbiology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, China
| | - Ping Xu
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Tao Dong
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
- Department of Immunology and Microbiology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, China
- * E-mail:
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18
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Mounting, structure and autocleavage of a type VI secretion-associated Rhs polymorphic toxin. Nat Commun 2021; 12:6998. [PMID: 34853317 PMCID: PMC8636562 DOI: 10.1038/s41467-021-27388-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 11/15/2021] [Indexed: 12/30/2022] Open
Abstract
Bacteria have evolved toxins to outcompete other bacteria or to hijack host cell pathways. One broad family of bacterial polymorphic toxins gathers multidomain proteins with a modular organization, comprising a C-terminal toxin domain fused to a N-terminal domain that adapts to the delivery apparatus. Polymorphic toxins include bacteriocins, contact-dependent growth inhibition systems, and specialized Hcp, VgrG, PAAR or Rhs Type VI secretion (T6SS) components. We recently described and characterized Tre23, a toxin domain fused to a T6SS-associated Rhs protein in Photorhabdus laumondii, Rhs1. Here, we show that Rhs1 forms a complex with the T6SS spike protein VgrG and the EagR chaperone. Using truncation derivatives and cross-linking mass spectrometry, we demonstrate that VgrG-EagR-Rhs1 complex formation requires the VgrG C-terminal β-helix and the Rhs1 N-terminal region. We then report the cryo-electron-microscopy structure of the Rhs1-EagR complex, demonstrating that the Rhs1 central region forms a β-barrel cage-like structure that encapsulates the C-terminal toxin domain, and provide evidence for processing of the Rhs1 protein through aspartyl autoproteolysis. We propose a model for Rhs1 loading on the T6SS, transport and delivery into the target cell.
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19
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Jumper J, Evans R, Pritzel A, Green T, Figurnov M, Ronneberger O, Tunyasuvunakool K, Bates R, Žídek A, Potapenko A, Bridgland A, Meyer C, Kohl SAA, Ballard AJ, Cowie A, Romera-Paredes B, Nikolov S, Jain R, Adler J, Back T, Petersen S, Reiman D, Clancy E, Zielinski M, Steinegger M, Pacholska M, Berghammer T, Bodenstein S, Silver D, Vinyals O, Senior AW, Kavukcuoglu K, Kohli P, Hassabis D. Highly accurate protein structure prediction with AlphaFold. Nature 2021; 596:583-589. [PMID: 34265844 PMCID: PMC8371605 DOI: 10.1038/s41586-021-03819-2] [Citation(s) in RCA: 15835] [Impact Index Per Article: 5278.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 07/12/2021] [Indexed: 02/07/2023]
Abstract
Proteins are essential to life, and understanding their structure can facilitate a mechanistic understanding of their function. Through an enormous experimental effort1-4, the structures of around 100,000 unique proteins have been determined5, but this represents a small fraction of the billions of known protein sequences6,7. Structural coverage is bottlenecked by the months to years of painstaking effort required to determine a single protein structure. Accurate computational approaches are needed to address this gap and to enable large-scale structural bioinformatics. Predicting the three-dimensional structure that a protein will adopt based solely on its amino acid sequence-the structure prediction component of the 'protein folding problem'8-has been an important open research problem for more than 50 years9. Despite recent progress10-14, existing methods fall far short of atomic accuracy, especially when no homologous structure is available. Here we provide the first computational method that can regularly predict protein structures with atomic accuracy even in cases in which no similar structure is known. We validated an entirely redesigned version of our neural network-based model, AlphaFold, in the challenging 14th Critical Assessment of protein Structure Prediction (CASP14)15, demonstrating accuracy competitive with experimental structures in a majority of cases and greatly outperforming other methods. Underpinning the latest version of AlphaFold is a novel machine learning approach that incorporates physical and biological knowledge about protein structure, leveraging multi-sequence alignments, into the design of the deep learning algorithm.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Martin Steinegger
- School of Biological Sciences, Seoul National University, Seoul, South Korea
- Artificial Intelligence Institute, Seoul National University, Seoul, South Korea
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20
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Robinson L, Liaw J, Omole Z, Xia D, van Vliet AHM, Corcionivoschi N, Hachani A, Gundogdu O. Bioinformatic Analysis of the Campylobacter jejuni Type VI Secretion System and Effector Prediction. Front Microbiol 2021; 12:694824. [PMID: 34276628 PMCID: PMC8285248 DOI: 10.3389/fmicb.2021.694824] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 06/07/2021] [Indexed: 12/30/2022] Open
Abstract
The Type VI Secretion System (T6SS) has important roles relating to bacterial antagonism, subversion of host cells, and niche colonisation. Campylobacter jejuni is one of the leading bacterial causes of human gastroenteritis worldwide and is a commensal coloniser of birds. Although recently discovered, the T6SS biological functions and identities of its effectors are still poorly defined in C. jejuni. Here, we perform a comprehensive bioinformatic analysis of the C. jejuni T6SS by investigating the prevalence and genetic architecture of the T6SS in 513 publicly available genomes using C. jejuni 488 strain as reference. A unique and conserved T6SS cluster associated with the Campylobacter jejuni Integrated Element 3 (CJIE3) was identified in the genomes of 117 strains. Analyses of the T6SS-positive 488 strain against the T6SS-negative C. jejuni RM1221 strain and the T6SS-positive plasmid pCJDM202 carried by C. jejuni WP2-202 strain defined the “T6SS-containing CJIE3” as a pathogenicity island, thus renamed as Campylobacter jejuni Pathogenicity Island-1 (CJPI-1). Analysis of CJPI-1 revealed two canonical VgrG homologues, CJ488_0978 and CJ488_0998, harbouring distinct C-termini in a genetically variable region downstream of the T6SS operon. CJPI-1 was also found to carry a putative DinJ-YafQ Type II toxin-antitoxin (TA) module, conserved across pCJDM202 and the genomic island CJIE3, as well as several open reading frames functionally predicted to encode for nucleases, lipases, and peptidoglycan hydrolases. This comprehensive in silico study provides a framework for experimental characterisation of T6SS-related effectors and TA modules in C. jejuni.
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Affiliation(s)
- Luca Robinson
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Janie Liaw
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Zahra Omole
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Dong Xia
- Comparative Biomedical Sciences, Royal Veterinary College, London, United Kingdom
| | - Arnoud H M van Vliet
- School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Nicolae Corcionivoschi
- Bacteriology Branch, Veterinary Sciences Division, Agri-Food and Biosciences Institute, Belfast, United Kingdom.,Bioengineering of Animal Science Resources, Banat University of Agricultural Sciences and Veterinary Medicine - King Michael the I of Romania, Timisoara, Romania
| | - Abderrahman Hachani
- The Peter Doherty Institute for Infection and Immunity, Department of Microbiology and Immunology, University of Melbourne, Melbourne, VIC, Australia
| | - Ozan Gundogdu
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
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21
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Manera K, Kamal F, Burkinshaw B, Dong TG. Essential functions of chaperones and adaptors of protein secretion systems in Gram-negative bacteria. FEBS J 2021; 289:4704-4717. [PMID: 34092034 DOI: 10.1111/febs.16056] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 05/18/2021] [Accepted: 06/04/2021] [Indexed: 01/02/2023]
Abstract
Equipped with a plethora of secreted toxic effectors, protein secretion systems are essential for bacteria to interact with and manipulate their neighboring environment to survive in host microbiota and other highly competitive communities. While effectors have received spotlight attention in secretion system studies, many require accessory chaperone and adaptor proteins for proper folding/unfolding and stability throughout the secretion process. Here, we review the functions of chaperones and adaptors of three protein secretions systems, type 3 secretion system (T3SS), type 4 secretion system (T4SS), and type 6 secretion system (T6SS), which are employed by many Gram-negative bacterial pathogens to deliver toxins to bacterial, plant, and mammalian host cells through direct contact. Since chaperone and adaptor functions of the T3SS and the T4SS are relatively well studied, we discuss in detail the methods of chaperone-facilitated effector secretion by the T6SS and highlight commonalities between the effector chaperone/adaptor proteins of these diverse secretion systems. While the chaperones and adaptors are generally referred to as accessory proteins as they are not directly involved in toxicities to target cells, they are nonetheless vital for the biological functions of the secretion systems. Future research on biochemical and structural properties of these chaperones will not only elucidate the mechanisms of chaperone-effector binding and release process but also facilitate custom design of cargo effectors to be translocated by these widespread secretion systems for biotechnological applications.
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Affiliation(s)
- Kevin Manera
- Department of Ecosystem and Public Health, University of Calgary, Canada
| | - Fatima Kamal
- Department of Ecosystem and Public Health, University of Calgary, Canada
| | | | - Tao G Dong
- Department of Ecosystem and Public Health, University of Calgary, Canada.,State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, China
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22
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Jurėnas D, Journet L. Activity, delivery, and diversity of Type VI secretion effectors. Mol Microbiol 2020; 115:383-394. [PMID: 33217073 DOI: 10.1111/mmi.14648] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 11/10/2020] [Accepted: 11/13/2020] [Indexed: 12/28/2022]
Abstract
The bacterial type VI secretion system (T6SS) system is a contractile secretion apparatus that delivers proteins to neighboring bacterial or eukaryotic cells. Antibacterial effectors are mostly toxins that inhibit the growth of other species and help to dominate the niche. A broad variety of these toxins cause cell lysis of the prey cell by disrupting the cell envelope. Other effectors are delivered into the cytoplasm where they affect DNA integrity, cell division or exhaust energy resources. The modular nature of T6SS machinery allows different means of recruitment of toxic effectors to secreted inner tube and spike components that act as carriers. Toxic effectors can be translationally fused to the secreted components or interact with them through specialized structural domains. These interactions can also be assisted by dedicated chaperone proteins. Moreover, conserved sequence motifs in effector-associated domains are subject to genetic rearrangements and therefore engage in the diversification of the arsenal of toxic effectors. This review discusses the diversity of T6SS secreted toxins and presents current knowledge about their loading on the T6SS machinery.
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Affiliation(s)
- Dukas Jurėnas
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université-CNRS, UMR 7255, Marseille, France
| | - Laure Journet
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université-CNRS, UMR 7255, Marseille, France
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23
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Drebes Dörr NC, Blokesch M. Interbacterial competition and anti-predatory behaviour of environmental Vibrio cholerae strains. Environ Microbiol 2020; 22:4485-4504. [PMID: 32885535 PMCID: PMC7702109 DOI: 10.1111/1462-2920.15224] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 08/31/2020] [Accepted: 09/01/2020] [Indexed: 12/21/2022]
Abstract
Vibrio cholerae isolates responsible for cholera pandemics represent only a small portion of the diverse strains belonging to this species. Indeed, most V. cholerae are encountered in aquatic environments. To better understand the emergence of pandemic lineages, it is crucial to discern what differentiates pandemic strains from their environmental relatives. Here, we studied the interaction of environmental V. cholerae with eukaryotic predators or competing bacteria and tested the contributions of the haemolysin and the type VI secretion system (T6SS) to those interactions. Both of these molecular weapons are constitutively active in environmental isolates but subject to tight regulation in the pandemic clade. We showed that several environmental isolates resist amoebal grazing and that this anti‐grazing defense relies on the strains' T6SS and its actincross‐linking domain (ACD)‐containing tip protein. Strains lacking the ACD were unable to defend themselves against grazing amoebae but maintained high levels of T6SS‐dependent interbacterial killing. We explored the latter phenotype through whole‐genome sequencing of 14 isolates, which unveiled a wide array of novel T6SS effector and (orphan) immunity proteins. By combining these in silico predictions with experimental validations, we showed that highly similar but non‐identical immunity proteins were insufficient to provide cross‐immunity among those wild strains.
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Affiliation(s)
- Natália C Drebes Dörr
- Laboratory of Molecular Microbiology, Global Health Institute, School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, CH-1015, Switzerland
| | - Melanie Blokesch
- Laboratory of Molecular Microbiology, Global Health Institute, School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, CH-1015, Switzerland
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24
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Weis F, Hagen WJH. Combining high throughput and high quality for cryo-electron microscopy data collection. Acta Crystallogr D Struct Biol 2020; 76:724-728. [PMID: 32744254 PMCID: PMC7397495 DOI: 10.1107/s2059798320008347] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 06/23/2020] [Indexed: 01/24/2023] Open
Abstract
Cryo-electron microscopy (cryo-EM) can be used to elucidate the 3D structure of macromolecular complexes. Driven by technological breakthroughs in electron-microscope and electron-detector development, coupled with improved image-processing procedures, it is now possible to reach high resolution both in single-particle analysis and in cryo-electron tomography and subtomogram-averaging approaches. As a consequence, the way in which cryo-EM data are collected has changed and new challenges have arisen in terms of microscope alignment, aberration correction and imaging parameters. This review describes how high-end data collection is performed at the EMBL Heidelberg cryo-EM platform, presenting recent microscope implementations that allow an increase in throughput while maintaining aberration-free imaging and the optimization of acquisition parameters to collect high-resolution data.
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Affiliation(s)
- Felix Weis
- The Cryo-Electron Microscopy Service Platform, Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Wim J. H. Hagen
- The Cryo-Electron Microscopy Service Platform, Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
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