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Wang Y, Zeng M, Xia L, Valerie Olovo C, Su Z, Zhang Y. Bacterial strategies for immune systems - Role of the type VI secretion system. Int Immunopharmacol 2023; 114:109550. [PMID: 36525796 DOI: 10.1016/j.intimp.2022.109550] [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: 09/06/2022] [Revised: 11/09/2022] [Accepted: 12/02/2022] [Indexed: 12/15/2022]
Abstract
The process of host infection by bacteria is complicated. Bacterial infections strongly induce the host immune system, which necessitates a robust clearance of the infection. However, bacteria have over time developed strategies that enable their evasion of attacks by the host immune system. One such strategy is the type VI secretion system (T6SS), a special needle-like secretion system that is widespread in Gram-negative bacteria and is responsible for delivering effector proteins into the external bacterial environment or directly into the host cell cytosol. Bacterial T6SS and its secreted effector proteins play an important role in the interaction between bacteria and host immune system. They also serve as antigens that are employed in the development of vaccines for clinical trials as well as future vaccine candidates. This review focuses mainly on aspects of T6SS effectors that impact the strength of the host immune system, including inflammation, autophagy, and apoptosis (silent programmed cell death). The T6SS-based vaccines are also described.
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Affiliation(s)
- Yurou Wang
- Institute for Medical Immunology of Jiangsu University, Affiliated Hospital of Jiangsu University, Zhenjiang, Jiangsu 212013, China; Department of Biochemistry and Molecular Biology, Jiangsu University School of Medicine, Zhenjiang, Jiangsu 212013, China
| | - Minmin Zeng
- Department of Biochemistry and Molecular Biology, Jiangsu University School of Medicine, Zhenjiang, Jiangsu 212013, China
| | - Lin Xia
- Department of Laboratory Medicine, Affiliated Hospital of Jiangsu University, Zhenjiang 212001, China; International Genome Center, Jiangsu University, Zhenjiang 212013, China
| | - Chinasa Valerie Olovo
- Department of Biochemistry and Molecular Biology, Jiangsu University School of Medicine, Zhenjiang, Jiangsu 212013, China
| | - Zhaoliang Su
- Institute for Medical Immunology of Jiangsu University, Affiliated Hospital of Jiangsu University, Zhenjiang, Jiangsu 212013, China; International Genome Center, Jiangsu University, Zhenjiang 212013, China
| | - Ying Zhang
- Institute for Medical Immunology of Jiangsu University, Affiliated Hospital of Jiangsu University, Zhenjiang, Jiangsu 212013, China; Department of Biochemistry and Molecular Biology, Jiangsu University School of Medicine, Zhenjiang, Jiangsu 212013, China.
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Ma R, Liu Y, Gan J, Qiao H, Ma J, Zhang Y, Bu Y, Shao S, Zhang Y, Wang Q. OUP accepted manuscript. Nucleic Acids Res 2022; 50:3777-3798. [PMID: 35325196 PMCID: PMC9023278 DOI: 10.1093/nar/gkac180] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 02/25/2022] [Accepted: 03/07/2022] [Indexed: 11/14/2022] Open
Affiliation(s)
| | | | | | - Haoxian Qiao
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Jiabao Ma
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Yi Zhang
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Yifan Bu
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Shuai Shao
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China
- Shanghai Engineering Research Center of Maricultured Animal Vaccines, Shanghai 200237, China
| | - Yuanxing Zhang
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China
- Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai 519000, China
- Shanghai Engineering Research Center of Maricultured Animal Vaccines, Shanghai 200237, China
| | - Qiyao Wang
- To whom correspondence should be addressed. Tel: +86 21 64253306; Fax: +86 21 64253306;
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Qin L, Wang X, Gao Y, Bi K, Wang W. Roles of EvpP in Edwardsiella piscicida-Macrophage Interactions. Front Cell Infect Microbiol 2020; 10:53. [PMID: 32117819 PMCID: PMC7033576 DOI: 10.3389/fcimb.2020.00053] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Accepted: 01/28/2020] [Indexed: 12/15/2022] Open
Abstract
Edwardsiella piscicida is found to be an important facultative intracellular pathogen with a broad host range. These organisms can replicate and survive within host macrophages to escape from the subversion of the immune defense. E. piscicida-macrophage interaction is very important in determining the outcome of edwardsiellasis. As an effector protein of E. piscicida T6SS, EvpP has been determined to be a very important virulence factor for E. piscicida, although its precise role in E. piscicida-macrophage interactions is not yet clear. In this study, the roles of EvpP in E. piscicida-macrophage interactions were characterized. Here, we constructed the deletion mutants of evpP (ΔevpP) and complementation (ΔevpP-C) by the allelic exchange method. Compared to wild type strain (WT), ΔevpP was found to be attenuated for growth within macrophages. In line with this observation, we found its survival capacity was lower than WT under oxidative and acid stress in vitro, which simulate conditions encountered in host macrophages. Attenuation of ΔevpP also correlated with enhanced activation of macrophages, as reflected by augmented NO production in ΔevpP-treated macrophages. Moreover, compared to WT, ΔevpP induced markedly increased apoptosis of macrophages, characterized by increased Annexin V binding and the activation of cleaved caspase-3. These findings provided strong evidence that EvpP is involved in the process of E. piscicida-macrophage interactions and is required for its survival and replication in macrophages. Thus, we propose that EvpP might be an important factor that controlling the fate of E. piscicida inside macrophages. To further exploring the underlying mechanism of EvpP action, the cDNA library was constructed from E. piscicida-infected macrophages and a yeast two-hybrid screen was performed to search for cellular proteins interacting with EvpP. Ribosomal protein S5 (RPS5) was identified as a target of EvpP. Furthermore, the interaction was validated with co-immunoprecipitation assay. This result implies that the observed effect of EvpP on macrophages might be related to RPS5-mediated regulation, contributing to a better understanding of the mechanisms of EvpP involved in E. piscicida-macrophage interactions.
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Affiliation(s)
- Lei Qin
- Jiangsu Key Laboratory of Marine Biotechnology, College of Marine Life and Fisheries, Jiangsu Ocean University, Lianyungang, China.,Co-Innovation Center of Jiangsu Marine Bio-industry Technology, Lianyungang, China
| | - Xingqiang Wang
- Jiangsu Key Laboratory of Marine Biotechnology, College of Marine Life and Fisheries, Jiangsu Ocean University, Lianyungang, China
| | - Yingli Gao
- Jiangsu Key Laboratory of Marine Biotechnology, College of Marine Life and Fisheries, Jiangsu Ocean University, Lianyungang, China
| | - Keran Bi
- Jiangsu Key Laboratory of Marine Biotechnology, College of Marine Life and Fisheries, Jiangsu Ocean University, Lianyungang, China
| | - Weixia Wang
- Jiangsu Key Laboratory of Marine Biotechnology, College of Marine Life and Fisheries, Jiangsu Ocean University, Lianyungang, China
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Hsieh PF, Lu YR, Lin TL, Lai LY, Wang JT. Klebsiella pneumoniae Type VI Secretion System Contributes to Bacterial Competition, Cell Invasion, Type-1 Fimbriae Expression, and In Vivo Colonization. J Infect Dis 2019; 219:637-647. [PMID: 30202982 PMCID: PMC6350951 DOI: 10.1093/infdis/jiy534] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 09/03/2018] [Indexed: 01/25/2023] Open
Abstract
Background We previously isolated a Klebsiella pneumoniae strain, NTUH-K2044, from a community-acquired pyogenic liver abscess (PLA) patient. Analysis of the NTUH-K2044 genome revealed that this strain harbors 2 putative type VI secretion system (T6SS)-encoding gene clusters. Methods The distribution of T6SS genes in the PLA and intestinal-colonizing K pneumoniae clinical isolates was examined. icmF1-, icmF2-, icmF1/icmF2-, and hcp-deficient K pneumoniae strains were constructed using an unmarked deletion method. The roles of T6SSs in antibacterial activity, type-1 fimbriae expression, cell adhesion, and invasion and intestinal colonization were determined. Results The prevalence of T6SSs is higher in the PLA strains than in the intestinal-colonizing strains (37 of 42 vs 54 of 130). Deletion of icmF1/icmF2 and hcp genes significantly reduced interbacterial and intrabacterial killing. Strain deleted for icmF1 and icmF2 exhibited decreased transcriptional expression of type-1 fimbriae and reduced adherence to and invasion of human colorectal epithelial cells and was attenuated for in vivo competition to enable colonization of the host gut. Finally, Hcp expression in K pneumoniae was silenced by the histone-like nucleoid structuring protein via direct binding. Conclusions These results provide new insights into T6SS-mediated bacterial competition and attachment in K pneumoniae and could facilitate the prevention of K pneumoniae infection.
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Affiliation(s)
- Pei-Fang Hsieh
- Department of Microbiology, National Taiwan University College of Medicine, Taipei
| | - Yi-Rou Lu
- Department of Microbiology, National Taiwan University College of Medicine, Taipei
| | - Tzu-Lung Lin
- Department of Microbiology, National Taiwan University College of Medicine, Taipei
| | - Li-Yin Lai
- Department of Microbiology, National Taiwan University College of Medicine, Taipei
| | - Jin-Town Wang
- Department of Microbiology, National Taiwan University College of Medicine, Taipei.,Department of Internal Medicine, National Taiwan University Hospital, Taipei
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Crystal structures of the kinase domain of PpkA, a key regulatory component of T6SS, reveal a general inhibitory mechanism. Biochem J 2018; 475:2209-2224. [DOI: 10.1042/bcj20180077] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Revised: 06/01/2018] [Accepted: 06/01/2018] [Indexed: 11/17/2022]
Abstract
The type VI secretion system (T6SS) is a versatile and widespread export system found in many Gram-negative bacteria that delivers effector proteins into target cells. The functions of T6SSs are tightly regulated by diverse mechanisms at multiple levels, including post-translational modification through threonine phosphorylation via the Ser/Thr protein kinase (STPK) PpkA. Here, we identified that PpkA is essential for T6SS secretion in Serratia marcescens since its deletion eliminated the secretion of haemolysin co-regulated protein, while the periplasmic and transmembrane portion of PpkA was found to be disposable for T6SS secretion. We further determined the crystal structure of the kinase domain of PpkA (PpkA-294). The structure of PpkA-294 was determined in its apo form to a 1.6 Å resolution as well as in complex with ATP to a 1.41 Å resolution and with an ATP analogue AMP-PCP to a 1.45 Å resolution. The residues in the activation loop of PpkA-294 were fully determined, and the N-terminus of the loop was folded into an unprecedented inhibitory helix, revealing that the PpkA kinase domain was in an auto-inhibitory state. The ternary MgATP–PpkA-294 complex was also inactive with nucleotide ribose and phosphates in unexpected and unproductive conformations. The αC-helix in the inactive PpkA-294 adopted a conformation towards the active site but with the conserved glutamate in the helix rotated away, which we suggest to be a general conformation for all STPK kinases in the inactive form. Structural comparison of PpkA with its eukaryotic homologues reinforced the universal regulation mechanism of protein kinases.
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Type VI secretion system contributes to Enterohemorrhagic Escherichia coli virulence by secreting catalase against host reactive oxygen species (ROS). PLoS Pathog 2017; 13:e1006246. [PMID: 28288207 PMCID: PMC5363993 DOI: 10.1371/journal.ppat.1006246] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 03/23/2017] [Accepted: 02/16/2017] [Indexed: 01/19/2023] Open
Abstract
Enterohemorrhagic Escherichia coli (EHEC) is one major type of contagious and foodborne pathogens. The type VI secretion system (T6SS) has been shown to be involved in the bacterial pathogenicity and bacteria-bacteria competition. Here, we show that EHEC could secrete a novel effector KatN, a Mn-containing catalase, in a T6SS-dependent manner. Expression of katN is promoted by RpoS and OxyR and repressed by H-NS, and katN contributes to bacterial growth under oxidative stress in vitro. KatN could be secreted into host cell cytosol after EHEC is phagocytized by macrophage, which leads to decreased level of intracellular reactive oxygen species (ROS) and facilitates the intramacrophage survival of EHEC. Finally, animal model results show that the deletion mutant of T6SS was attenuated in virulence compared with the wild type strain, while the deletion mutant of katN had comparable virulence to the wild type strain. Taken together, our findings suggest that EHEC could sense oxidative stress in phagosome and decrease the host cell ROS by secreting catalase KatN to facilitate its survival in the host cells.
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Cui S, Xiao J, Wang Q, Zhang Y. H-NS binding to evpB and evpC and repressing T6SS expression in fish pathogen Edwardsiella piscicida. Arch Microbiol 2016; 198:653-61. [PMID: 27125651 DOI: 10.1007/s00203-016-1226-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2015] [Revised: 03/11/2016] [Accepted: 04/15/2016] [Indexed: 11/30/2022]
Abstract
Edwardsiella piscicida is an important causative agent of hemorrhagic septicemia in fish and infects both cultured and wild fish species. Type VI secretion system (T6SS) was proved to play important roles in pathogenesis of E. piscicida. In this study, it was demonstrated that the expression of T6SS genes evpB and evpC was under control of the global regulator H-NS in E. piscicida and the transcriptional level of evpB and evpC was significantly down-regulated by H-NS. Compared to the wild type, the transcriptional levels of evpB and evpC were up-regulated in hns null mutant, while down-regulated in hns overexpression strain. The results of EMSA and DNase I footprinting revealed that H-NS protein directly bound to upstream region of evpC at multiple sites. A high-affinity motif with a 9-nucleotide sequence 5'-ATATAAAAT-3' was defined for H-NS preferential recognition based on the feature of the binding sites. These results indicated that H-NS acted cooperatively to form extended nucleoprotein filaments on target DNA. Site-directed mutagenesis of H-NS further showed that R86 played an essential role in T6SS gene binding. These findings highlighted the mechanisms underlying the complex regulation network of T6SS by H-NS in E. piscicida.
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Affiliation(s)
- Shilei Cui
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, 200237, China
| | - Jingfan Xiao
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, 200237, China. .,Shanghai Engineering Research Center of Maricultured Animal Vaccines, Shanghai, China.
| | - Qiyao Wang
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, 200237, China.,Shanghai Engineering Research Center of Maricultured Animal Vaccines, Shanghai, China.,Shanghai Collaborative Innovation Center for Biomanufacturing Technology, Shanghai, China
| | - Yuanxing Zhang
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, 200237, China.,Shanghai Engineering Research Center of Maricultured Animal Vaccines, Shanghai, China.,Shanghai Collaborative Innovation Center for Biomanufacturing Technology, Shanghai, China
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H-NS Silencing of the Salmonella Pathogenicity Island 6-Encoded Type VI Secretion System Limits Salmonella enterica Serovar Typhimurium Interbacterial Killing. Infect Immun 2015; 83:2738-50. [PMID: 25916986 DOI: 10.1128/iai.00198-15] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2015] [Accepted: 04/16/2015] [Indexed: 12/26/2022] Open
Abstract
The secretion of bacterial toxin proteins is achieved by dedicated machineries called secretion systems. The type VI secretion system (T6SS) is a widespread versatile machine used for the delivery of protein toxins to both prokaryotic and eukaryotic cells. In Salmonella enterica serovar Typhimurium, the expression of the T6SS genes is activated during macrophage or mouse infection. Here, we show that the T6SS gene cluster is silenced by the histone-like nucleoid structuring H-NS protein using a combination of reporter fusions, electrophoretic mobility shift assays, DNase footprinting, and fluorescence microscopy. We further demonstrate that derepression of the S. Typhimurium T6SS genes induces T6SS-dependent intoxication of competing bacteria. Our results suggest that relieving T6SS H-NS silencing may be used as a sense-and-kill mechanism that will help S. Typhimurium to homogenize and synchronize the microbial population to gain efficiency during infection.
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