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Shao X, Wu Q, Li L, He W, He X, Cheng D, Murero A, Lin L, Wang L, Zhong C, Huang L, Qian G. Adapting the inoculation methods of kiwifruit canker disease to identify efficient biocontrol bacteria from branch microbiome. MOLECULAR PLANT PATHOLOGY 2024; 25:e13399. [PMID: 37921929 PMCID: PMC10788592 DOI: 10.1111/mpp.13399] [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: 10/05/2023] [Accepted: 10/05/2023] [Indexed: 11/05/2023]
Abstract
Pseudomonas syringae pv. actinidiae (Psa), the bacterium that causes kiwifruit bacterial canker, is a common field occurrence that is difficult to control globally. Currently, exploring the resources for efficient biocontrol bacteria is a hot spot in the field. The common strategy for isolating biocontrol bacteria is to directly isolate biocontrol bacteria that can secrete diffusible antibacterial substances, most of which are members of Bacillus, Pseudomonas and Streptomycetaceae, from disease samples or soil. Here, we report a new approach by adapting the typical isolation methods of kiwifruit canker disease to identify efficient biocontrol bacteria from the branch microbiome. Using this unique approach, we isolated a group of kiwifruit biocontrol agents (KBAs) from the branch microbiome of Psa-resistant varieties. Thirteen of these showed no antagonistic activity in vitro, which depends on the secretion of antibacterial compounds. However, they exhibited antibacterial activity via cell-to-cell contacts mimicked by co-culture on agar plates. Through biocontrol tests on plants, two isolates, KBA13 and KBA19, demonstrated their effectiveness by protecting kiwifruit branches from Psa infection. Using KBA19, identified as Pantoea endophytica, as a representative, we found that this bacterium uses the type VI secretion system (T6SS) as the main contact-dependent antibacterial weapon that acts via translocating toxic effector proteins into Psa cells to induce cell death, and that this capacity expressed by KBA19 is common to various Psa strains from different countries. Our findings highlight a new strategy to identify efficient biocontrol agents that use the T6SS to function in an antibacterial metabolite-independent manner to control wood diseases.
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Affiliation(s)
- Xiaolong Shao
- Key Laboratory of Integrated Management of Crop Diseases and PestsCollege of Plant Protection, State Key Laboratory of Biological Interactions and Crop Health, Nanjing Agricultural UniversityNanjingChina
| | - Qianhua Wu
- Key Laboratory of Integrated Management of Crop Diseases and PestsCollege of Plant Protection, State Key Laboratory of Biological Interactions and Crop Health, Nanjing Agricultural UniversityNanjingChina
| | - Li Li
- CAS Engineering Laboratory for Kiwifruit Industrial Technology, CAS Key Laboratory of Plant Germplasm Enhancement and Specialty AgricultureWuhan Botanical Garden, Chinese Academy of SciencesWuhanHubei ProvinceChina
| | - Weimei He
- Key Laboratory of Integrated Management of Crop Diseases and PestsCollege of Plant Protection, State Key Laboratory of Biological Interactions and Crop Health, Nanjing Agricultural UniversityNanjingChina
| | - Xueting He
- Key Laboratory of Integrated Management of Crop Diseases and PestsCollege of Plant Protection, State Key Laboratory of Biological Interactions and Crop Health, Nanjing Agricultural UniversityNanjingChina
| | - Dongjin Cheng
- Key Laboratory of Integrated Management of Crop Diseases and PestsCollege of Plant Protection, State Key Laboratory of Biological Interactions and Crop Health, Nanjing Agricultural UniversityNanjingChina
| | - Aprodisia Murero
- Key Laboratory of Integrated Management of Crop Diseases and PestsCollege of Plant Protection, State Key Laboratory of Biological Interactions and Crop Health, Nanjing Agricultural UniversityNanjingChina
| | - Long Lin
- Key Laboratory of Integrated Management of Crop Diseases and PestsCollege of Plant Protection, State Key Laboratory of Biological Interactions and Crop Health, Nanjing Agricultural UniversityNanjingChina
| | - Limin Wang
- Key Laboratory of Integrated Management of Crop Diseases and PestsCollege of Plant Protection, State Key Laboratory of Biological Interactions and Crop Health, Nanjing Agricultural UniversityNanjingChina
| | - Caihong Zhong
- CAS Engineering Laboratory for Kiwifruit Industrial Technology, CAS Key Laboratory of Plant Germplasm Enhancement and Specialty AgricultureWuhan Botanical Garden, Chinese Academy of SciencesWuhanHubei ProvinceChina
| | - Lili Huang
- State Key Laboratory of Crop Stress Biology for Arid AreasCollege of Plant Protection, Northwest A&F UniversityYanglingShanxiChina
| | - Guoliang Qian
- Key Laboratory of Integrated Management of Crop Diseases and PestsCollege of Plant Protection, State Key Laboratory of Biological Interactions and Crop Health, Nanjing Agricultural UniversityNanjingChina
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Liu W, Li M, Cao S, Ishaq HM, Zhao H, Yang F, Liu L. The Biological and Regulatory Role of Type VI Secretion System of Klebsiella pneumoniae. Infect Drug Resist 2023; 16:6911-6922. [PMID: 37928603 PMCID: PMC10624183 DOI: 10.2147/idr.s426657] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 09/30/2023] [Indexed: 11/07/2023] Open
Abstract
Bacteria communicate with their surroundings through diverse secretory systems, and the recently discovered Type VI Secretion System (T6SS) has gained significant attention. Klebsiella pneumoniae (K. pneumoniae), an opportunistic pathogen known for causing severe infections in both hospital and animal settings, possesses this intriguing T6SS. This system equips K. pneumoniae with a formidable armory of protein-based weaponry, enabling the delivery of toxins into neighboring cells, thus granting a substantial competitive advantage. Remarkably, the T6SS has also been associated with K. pneumoniae's ability to form biofilms and acquire resistance against antibiotics. However, the precise effects of the T6SS on K. pneumoniae's functions remain inadequately studied, despite research efforts to understand the intricacies of these mechanisms. This comprehensive review aims to provide an overview of the current knowledge regarding the biological functions and regulatory mechanisms of the T6SS in K. pneumoniae.
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Affiliation(s)
- Wenke Liu
- Department of Pathogenic Biology, School of Basic Medical Sciences, Xinxiang Medical University, Xinxiang, People’s Republic of China
| | - Min Li
- Department of Pathogenic Biology, School of Basic Medical Sciences, Xinxiang Medical University, Xinxiang, People’s Republic of China
| | - Shiwen Cao
- Department of Pathogenic Biology, School of Basic Medical Sciences, Xinxiang Medical University, Xinxiang, People’s Republic of China
| | - Hafiz Muhammad Ishaq
- Faculty of Veterinary and Animal Sciences, Muhammad Nawaz Shareef University of Agriculture, Multan, Pakistan
| | - Huajie Zhao
- Department of Pathogenic Biology, School of Basic Medical Sciences, Xinxiang Medical University, Xinxiang, People’s Republic of China
| | - Fan Yang
- Department of Pathogenic Biology, School of Basic Medical Sciences, Xinxiang Medical University, Xinxiang, People’s Republic of China
| | - Liang Liu
- Department of Pathogenic Biology, School of Basic Medical Sciences, Xinxiang Medical University, Xinxiang, People’s Republic of China
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3
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Chen Y, Guo R, Liang Y, Luo L, Han Y, Wang H, Zhang H, Liu Y, Zheng K, Shao H, Sung YY, Mok WJ, Wong LL, McMinn A, Wang M. Characterization and genomic analysis of a novel lytic phage vB_PstM_ZRG1 infecting Stutzerimonas stutzeri, representing a new viral genus, Elithevirus. Virus Res 2023; 334:199183. [PMID: 37499764 PMCID: PMC10404802 DOI: 10.1016/j.virusres.2023.199183] [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: 04/14/2023] [Revised: 07/20/2023] [Accepted: 07/24/2023] [Indexed: 07/29/2023]
Abstract
Stutzerimonas stutzeri is an opportunistic pathogen widely distributed in the environment and displays diverse metabolic capabilities. In this study, a novel lytic S. stutzeri phage, named vB_PstM_ZRG1, was isolated from the seawater in the East China Sea (29°09'N, 123°39'E). vB_PstM_ZRG1 was stable at temperatures ranging from -20°C to 65°C and across a wide range of pH values from 3 to 10. The genome of vB_PstM_ZRG1 was determined to be a double-stranded DNA with a genome size of 52,767 bp, containing 78 putative open reading frames (ORFs). Three auxiliary metabolic genes encoded by phage vB_PstM_ZRG1 were predicted, including Toll/interleukin-1 receptor (TIR) domain, proline-alanine-alanine-arginine (PAAR) protein and SGNH (Ser-Gly-Asn-His) family hydrolase, especially TIR domain is not common in isolated phages. Phylogenic and network analysis showed that vB_PstM_ZRG1 has low similarity to other phage genomes in the GenBank and IMG/VR database, and might represent a novel viral genus, named Elithevirus. Additionally, the distribution map results indicated that vB_PstM_ZRG1 could infect both extreme colds- and warm-type hosts in the marine environment. In summary, our finding provided basic information for further research on the relationship between S. stutzeri and their phages, and expanded our understanding of genomic characteristics, phylogenetic diversity and distribution of Elithevirus.
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Affiliation(s)
- Ying Chen
- College of Marine Life Sciences, Institute of Evolution and Marine Biodiversity, Frontiers Science Center for Deep Ocean Multispheres and Earth System, Center for Ocean Carbon Neutrality, Ocean University of China, Qingdao, China
| | - Ruizhe Guo
- College of Marine Life Sciences, Institute of Evolution and Marine Biodiversity, Frontiers Science Center for Deep Ocean Multispheres and Earth System, Center for Ocean Carbon Neutrality, Ocean University of China, Qingdao, China
| | - Yantao Liang
- College of Marine Life Sciences, Institute of Evolution and Marine Biodiversity, Frontiers Science Center for Deep Ocean Multispheres and Earth System, Center for Ocean Carbon Neutrality, Ocean University of China, Qingdao, China; UMT-OUC Joint Academic Centre for Marine Studies, Qingdao, China.
| | - Lin Luo
- College of Marine Life Sciences, Institute of Evolution and Marine Biodiversity, Frontiers Science Center for Deep Ocean Multispheres and Earth System, Center for Ocean Carbon Neutrality, Ocean University of China, Qingdao, China
| | - Ying Han
- College of Marine Life Sciences, Institute of Evolution and Marine Biodiversity, Frontiers Science Center for Deep Ocean Multispheres and Earth System, Center for Ocean Carbon Neutrality, Ocean University of China, Qingdao, China
| | - Hongmin Wang
- College of Marine Life Sciences, Institute of Evolution and Marine Biodiversity, Frontiers Science Center for Deep Ocean Multispheres and Earth System, Center for Ocean Carbon Neutrality, Ocean University of China, Qingdao, China
| | - Hong Zhang
- College of Marine Life Sciences, Institute of Evolution and Marine Biodiversity, Frontiers Science Center for Deep Ocean Multispheres and Earth System, Center for Ocean Carbon Neutrality, Ocean University of China, Qingdao, China
| | - Yundan Liu
- College of Marine Life Sciences, Institute of Evolution and Marine Biodiversity, Frontiers Science Center for Deep Ocean Multispheres and Earth System, Center for Ocean Carbon Neutrality, Ocean University of China, Qingdao, China
| | - Kaiyang Zheng
- College of Marine Life Sciences, Institute of Evolution and Marine Biodiversity, Frontiers Science Center for Deep Ocean Multispheres and Earth System, Center for Ocean Carbon Neutrality, Ocean University of China, Qingdao, China
| | - Hongbing Shao
- College of Marine Life Sciences, Institute of Evolution and Marine Biodiversity, Frontiers Science Center for Deep Ocean Multispheres and Earth System, Center for Ocean Carbon Neutrality, Ocean University of China, Qingdao, China; UMT-OUC Joint Academic Centre for Marine Studies, Qingdao, China
| | - Yeong Yik Sung
- UMT-OUC Joint Academic Centre for Marine Studies, Qingdao, China; Institute of Marine Biotechnology, Universiti Malaysia Terengganu, Kuala Terengganu, Malaysia
| | - Wen Jye Mok
- UMT-OUC Joint Academic Centre for Marine Studies, Qingdao, China; Institute of Marine Biotechnology, Universiti Malaysia Terengganu, Kuala Terengganu, Malaysia
| | - Li Lian Wong
- UMT-OUC Joint Academic Centre for Marine Studies, Qingdao, China; Institute of Marine Biotechnology, Universiti Malaysia Terengganu, Kuala Terengganu, Malaysia
| | - Andrew McMinn
- College of Marine Life Sciences, Institute of Evolution and Marine Biodiversity, Frontiers Science Center for Deep Ocean Multispheres and Earth System, Center for Ocean Carbon Neutrality, Ocean University of China, Qingdao, China; Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS, Australia
| | - Min Wang
- College of Marine Life Sciences, Institute of Evolution and Marine Biodiversity, Frontiers Science Center for Deep Ocean Multispheres and Earth System, Center for Ocean Carbon Neutrality, Ocean University of China, Qingdao, China; UMT-OUC Joint Academic Centre for Marine Studies, Qingdao, China; Haide College, Ocean University of China, Qingdao, China; The Affiliated Hospital of Qingdao University, Qingdao 266000, China.
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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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Pothula R, Lee MW, Patricia Stock S. Type 6 Secretion System components hcp and vgrG support mutualistic partnership between Xenorhabdus bovienii symbiont and Steinernema jollieti host. J Invertebr Pathol 2023; 198:107925. [PMID: 37087093 DOI: 10.1016/j.jip.2023.107925] [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: 10/17/2022] [Revised: 04/11/2023] [Accepted: 04/16/2023] [Indexed: 04/24/2023]
Abstract
Xenorhabdus, like other Gram-negative bacteria, possesses a Type 6 Secretion System (T6SS) which acts as a contact-dependent molecular syringe, delivering diverse proteins (effectors) directly into other cells. The number of T6SS loci encoded in Xenorhabdus genomes are variable both at the inter and intraspecific level. Some environmental isolates of Xenorhabdus bovienii, encode at least one T6SS locus while others possess two loci. Previous work conducted by our team demonstrated that X. bovienii [Jollieti strain SS-2004], which has two T6SSs (T6SS-1 and T6SS-2), hcp genes are required for biofilm formation. Additionally, while T6SS-1 hcp gene plays a role in the antibacterial competition, T6SS-2 hcp does not. In this study, we tested the hypothesis that vgrG genes are also involved in mutualistic and pathogenic interactions. For this purpose, targeted mutagenesis together with wet lab experiments including colonization, competition, biofilm, and virulence experiments, were carried out to assess the role of vgrG in the mutualistic and antagonistic interactions in the life cycle of XBJ. Our results revealed that vgrG genes are not required for biofilm formation but play a role in outcompeting other Xenorhabdus bacteria. Additionally, both vgrG and hcp genes are required to fully colonize the nematode host. We also demonstrated that hcp and vgrG genes in both T6SS clusters are needed to support the reproductive fitness of the nematodes. Overall, results from this study revealed that in X. bovieni jollieti strain, the twoT6SS clusters play an important role in the fitness of the nematodes in relation to colonization and reproduction. These results lay a foundation for further investigations on the functional significance of T6SSs in the mutualistic and pathogenic lifecycle of Xenorhabdus spp.
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Affiliation(s)
- Ratnasri Pothula
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, AZ, United States
| | - Min-Woo Lee
- Corn, Soybean, and Wheat Quality Research Lab, USDA-ARS Wooster, OH, United States
| | - S Patricia Stock
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, AZ, United States; College of Agriculture, California State University, Chico, CA, United States.
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Pérez-Lorente AI, Molina-Santiago C, de Vicente A, Romero D. Sporulation Activated via σ W Protects Bacillus from a Tse1 Peptidoglycan Hydrolase Type VI Secretion System Effector. Microbiol Spectr 2023; 11:e0504522. [PMID: 36916921 PMCID: PMC10100999 DOI: 10.1128/spectrum.05045-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 02/21/2023] [Indexed: 03/16/2023] Open
Abstract
Within bacterial communities, community members engage in interactions employing diverse offensive and defensive tools to reach coexistence. Extracellular-matrix production and sporulation are defensive mechanisms used by Bacillus subtilis cells when they interact with Pseudomonas chlororaphis strains expressing a type VI secretion system (T6SS). Here, we define Tse1 as the main toxin mobilized by the Pseudomonas chlororaphis T6SS that triggers sporulation in Bacillus subtilis. We characterize Tse1 as a peptidoglycan hydrolase that indirectly alters the dynamics and functionality of the Bacillus cell membrane. We also delineate the response of Bacillus cells to Tse1, which through the coordinated actions of the extracellular sigma factor σW and the cytoplasmic histidine kinases KinA and KinB, culminates in activation of the sporulation cascade. We propose that this cellular developmental response permits bacilli to defend against the toxicity of T6SS-mobilized Tse1 effector. IMPORTANCE The study of bacterial interactions is helping to define species-specific strategies used to modulate the competition dynamics underlying the development of community compositions. In this study, we deciphered the role of Pseudomonas T6SS when competing with Bacillus and the mechanism by which a T6SS-toxin modifies Bacillus physiology. We found that Pseudomonas triggers Bacillus sporulation by injecting through T6SS a toxin that we called Tse1. We found that Tse1 is a hydrolase that degrades Bacillus peptidoglycan and indirectly damages Bacillus membrane functionality. In addition, we demonstrated the mechanism by which Bacillus cells increase the sporulation rate upon recognition of the presence of Tse1. Interestingly, asporogenic Bacillus cells are more sensitive to T6SS activity, which led us to propose sporulation as a last resort of bacilli to overcome this family of toxins.
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Affiliation(s)
- Alicia I. Pérez-Lorente
- Instituto de Hortofruticultura Subtropical y Mediterránea La Mayora, Universidad de Málaga-Consejo Superior de Investigaciones Científicas, Departamento de Microbiología, Universidad de Málaga, Málaga, Spain
| | - Carlos Molina-Santiago
- Instituto de Hortofruticultura Subtropical y Mediterránea La Mayora, Universidad de Málaga-Consejo Superior de Investigaciones Científicas, Departamento de Microbiología, Universidad de Málaga, Málaga, Spain
| | - Antonio de Vicente
- Instituto de Hortofruticultura Subtropical y Mediterránea La Mayora, Universidad de Málaga-Consejo Superior de Investigaciones Científicas, Departamento de Microbiología, Universidad de Málaga, Málaga, Spain
| | - Diego Romero
- Instituto de Hortofruticultura Subtropical y Mediterránea La Mayora, Universidad de Málaga-Consejo Superior de Investigaciones Científicas, Departamento de Microbiología, Universidad de Málaga, Málaga, Spain
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Jurėnas D, Rey M, Byrne D, Chamot-Rooke J, Terradot L, Cascales E. Salmonella antibacterial Rhs polymorphic toxin inhibits translation through ADP-ribosylation of EF-Tu P-loop. Nucleic Acids Res 2022; 50:13114-13127. [PMID: 36484105 PMCID: PMC9825190 DOI: 10.1093/nar/gkac1162] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 11/11/2022] [Accepted: 12/07/2022] [Indexed: 12/13/2022] Open
Abstract
Rearrangement hot spot (Rhs) proteins are members of the broad family of polymorphic toxins. Polymorphic toxins are modular proteins composed of an N-terminal region that specifies their mode of secretion into the medium or into the target cell, a central delivery module, and a C-terminal domain that has toxic activity. Here, we structurally and functionally characterize the C-terminal toxic domain of the antibacterial Rhsmain protein, TreTu, which is delivered by the type VI secretion system of Salmonella enterica Typhimurium. We show that this domain adopts an ADP-ribosyltransferase fold and inhibits protein synthesis by transferring an ADP-ribose group from NAD+ to the elongation factor Tu (EF-Tu). This modification is specifically placed on the side chain of the conserved D21 residue located on the P-loop of the EF-Tu G-domain. Finally, we demonstrate that the TriTu immunity protein neutralizes TreTu activity by acting like a lid that closes the catalytic site and traps the NAD+.
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Affiliation(s)
- Dukas Jurėnas
- Correspondence may also be addressed to Dukas Jurėnas.
| | - Martial Rey
- Mass Spectrometry for Biology Unit, Université Paris Cité, Institut Pasteur, CNRS, UAR 2024, 75015 Paris, France
| | - Deborah Byrne
- Protein Expression Facility, Institut de Microbiologie de la Méditerranée (IMM), Aix-Marseille Université, CNRS, 13009 Marseille, France
| | - Julia Chamot-Rooke
- Mass Spectrometry for Biology Unit, Université Paris Cité, Institut Pasteur, CNRS, UAR 2024, 75015 Paris, France
| | - Laurent Terradot
- Laboratory of Molecular Microbiology and Structural Biochemistry, Institut de Biologie et Chimie des Protéines, Centre National de la Recherche Scientifique, Université de Lyon, UMR 5086, 69367 Lyon, France
| | - Eric Cascales
- To whom correspondence should be addressed. Tel: +33 491164462; Fax: +33 491712124;
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Analysis of Effector and Immunity Proteins of the GA2 Type VI Secretion Systems of Gut Bacteroidales. J Bacteriol 2022; 204:e0012222. [PMID: 35735993 PMCID: PMC9295542 DOI: 10.1128/jb.00122-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Three distinct genetic architectures (GAs) of Type VI secretion systems (T6SSs) have been described in gut Bacteroidales species, each with unique genes and characteristics. Unlike the GA3 T6SSs, potent antagonism has not yet been demonstrated for the GA1 or GA2 T6SSs. We previously showed that the GA2 T6SS loci are contained on integrative and conjugative elements and that there are five subtypes. Collectively, GA2 are the most prevalent Bacteroidales T6SSs in the human populations analyzed. In this study, we provide a comprehensive bioinformatic analysis of the three variable regions of GA2 T6SS loci, which encode toxic effector and immunity proteins. In total, we identified 63 distinct effectors encoded within 31 nonredundant GA2 loci, 18 of which do not have described motifs or predicted functions. We provide experimental evidence for toxin activity for four different GA2 effectors, showing that each functions only when present in the periplasm, and experimentally confirm their cognate immunity proteins. Our data demonstrate that each GA2 locus encodes at least three distinct effectors with targets in both the cytoplasm and the periplasm. The data also suggest that the effectors of a given locus are loaded onto the tube by different mechanisms, which may allow all three effectors encoded within a single GA2 locus with distinct antibacterial activity to be loaded onto a single T6 tube, increasing the antagonistic effect. IMPORTANCE Humans are colonized with many gut Bacteroidales species at high density, allowing for extensive opportunities for contact-dependent antagonism. To begin to understand the antagonistic potential of the GA2 T6SSs of the gut Bacteroidales, we performed bioinformatic and experimental analyses of the three divergent regions containing the toxin effector and immunity genes. We show that each GA2 T6SS locus encodes at least three distinct toxic effectors including toxins linked to Rhs and Hcp with cytoplasmic targets, and unlinked effectors with targets in the periplasm. The diversity and modality of effectors exceeds that of the GA1 or GA3 T6SS loci (M. J. Coyne, K. G. Roelofs, and L. E. Comstock, BMC Genomics 17:58, 2016, https://doi.org/10.1186/s12864-016-2377-z) and suggests that these T6SSs have the potential to be potent antibacterial weapons in the human gut.
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9
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Li W, Liu X, Tsui W, Xu A, Li D, Zhang X, Li P, Bian X, Zhang J. Identification and Comparative Genomic Analysis of Type VI Secretion Systems and Effectors in Klebsiella pneumoniae. Front Microbiol 2022; 13:853744. [PMID: 35633723 PMCID: PMC9134191 DOI: 10.3389/fmicb.2022.853744] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 04/14/2022] [Indexed: 01/26/2023] Open
Abstract
Klebsiella pneumoniae is a nosocomial opportunistic pathogen that can cause pneumonia, liver abscesses, and infections of the bloodstream. The resistance and pathogenicity of K. pneumoniae pose major challenges to clinical practice. However, the ecology and pathogenic mechanisms of K. pneumoniae have not been fully elucidated. Among these mechanisms, the secretion systems encoded by strains of the bacteria confer adaptive advantages depending on the niche occupied. The type VI secretion system (T6SS) is a multi-protein complex that delivers effector proteins to the extracellular environment or directly to eukaryotic or prokaryotic cells. T6SSs are widely distributed in Gram-negative bacteria and play an important role in bacterial virulence and the interactions between bacteria and other microorganisms or the environment. This study aimed to enhance the understanding of the characteristics of T6SSs in K. pneumoniae through an in-depth comparative genomic analysis of the T6SS in 241 sequenced strains of K. pneumoniae. We identified the T6SS loci, the synteny of the loci in different species, as well as the effectors and core T6SS-related genes in K. pneumoniae. The presence of a T6SS was a common occurrence in K. pneumoniae, and two T6SS clusters are the most prevalent. The variable region downstream of the gene vgrG usually encodes effector proteins. Conserved domain analysis indicated that the identified putative effectors in K. pneumoniae had the functions of lipase, ribonuclease, deoxyribonuclease, and polysaccharide hydrolase. However, some effectors did not contain predicted functional domains, and their specific functions have yet to be elucidated. This in silico study represents a detailed analysis of T6SS-associated genes in K. pneumoniae and provides a foundation for future studies on the mechanism(s) of T6SSs, especially effectors, which may generate new insights into pathogenicity and lead to the identification of proteins with novel antimicrobial properties.
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Affiliation(s)
- Wanzhen Li
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China
- Key Laboratory of Clinical Pharmacology of Antibiotics, Shanghai, China
- National Health Commission and National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, China
| | - Xiaofen Liu
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China
- Key Laboratory of Clinical Pharmacology of Antibiotics, Shanghai, China
- National Health Commission and National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, China
| | - Waitang Tsui
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Biochemistry, School of Life Sciences, Fudan University, Shanghai, China
| | - An Xu
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China
| | - Dan Li
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China
| | - Xuefei Zhang
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China
| | - Pei Li
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China
| | - Xingchen Bian
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China
- Key Laboratory of Clinical Pharmacology of Antibiotics, Shanghai, China
- National Health Commission and National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, China
| | - Jing Zhang
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China
- Key Laboratory of Clinical Pharmacology of Antibiotics, Shanghai, China
- National Health Commission and National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, China
- Phase I Unit, Huashan Hospital, Fudan University, Shanghai, China
- *Correspondence: Jing Zhang,
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Li Y, Yan X, Tao Z. Two Type VI Secretion DNase Effectors are Utilized for Interbacterial Competition in the Fish Pathogen Pseudomonas plecoglossicida. Front Microbiol 2022; 13:869278. [PMID: 35464968 PMCID: PMC9020831 DOI: 10.3389/fmicb.2022.869278] [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: 02/04/2022] [Accepted: 03/17/2022] [Indexed: 11/13/2022] Open
Abstract
Pseudomonas plecoglossicida is a facultative fish pathogen that possesses three distinct type VI secretion systems (named T6SS-1, T6SS-2, and T6SS-3). Our previous work indicated that only T6SS-2 of P. plecoglossicida mediates interbacterial competition. However, the antibacterial T6SS effectors and their functions are unclear. Here, we reported two T6SS effectors that mediate antibacterial activity. We first identified four putative antibacterial effectors (denoted as Txe1, Txe2, Txe3, and Txe4) and their cognate immunity proteins encoded in P. plecoglossicida strain XSDHY-P by analyzing the regions downstream of three vgrG genes. We showed that the growth of Escherichia coli cells expressing Txe1, Txe2, and Txe4 was inhibited, and these three effectors exhibited nuclease activity in vivo. The interbacterial competition assays with single- or multi-effector deletion mutants as attackers revealed that Txe1 was the predominant T6SS toxin of P. plecoglossicida strain XSDHY-P mediating the interbacterial killing. This work contributes to our understanding of bacterial effectors involved in the interbacterial competition.
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Affiliation(s)
- Yanyan Li
- School of Fisheries, Zhejiang Ocean University, Zhoushan, China
| | - Xiaojun Yan
- School of Fisheries, Zhejiang Ocean University, Zhoushan, China
| | - Zhen Tao
- School of Fisheries, Zhejiang Ocean University, Zhoushan, China
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