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Xun J, Zhang Z, Lv B, Lu D, Yang H, Shang G, Tan JX. A conserved ion channel function of STING mediates noncanonical autophagy and cell death. EMBO Rep 2024; 25:544-569. [PMID: 38177926 PMCID: PMC10897221 DOI: 10.1038/s44319-023-00045-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 12/12/2023] [Accepted: 12/14/2023] [Indexed: 01/06/2024] Open
Abstract
The cGAS/STING pathway triggers inflammation upon diverse cellular stresses such as infection, cellular damage, aging, and diseases. STING also triggers noncanonical autophagy, involving LC3 lipidation on STING vesicles through the V-ATPase-ATG16L1 axis, as well as induces cell death. Although the proton pump V-ATPase senses organelle deacidification in other contexts, it is unclear how STING activates V-ATPase for noncanonical autophagy. Here we report a conserved channel function of STING in proton efflux and vesicle deacidification. STING activation induces an electron-sparse pore in its transmembrane domain, which mediates proton flux in vitro and the deacidification of post-Golgi STING vesicles in cells. A chemical ligand of STING, C53, which binds to and blocks its channel, strongly inhibits STING-mediated proton flux in vitro. C53 fully blocks STING trafficking from the ER to the Golgi, but adding C53 after STING arrives at the Golgi allows for selective inhibition of STING-dependent vesicle deacidification, LC3 lipidation, and cell death, without affecting trafficking. The discovery of STING as a channel opens new opportunities for selective targeting of canonical and noncanonical STING functions.
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Affiliation(s)
- Jinrui Xun
- Xiangya School of Medicine, Central South University, Changsha, China
- Aging Institute, University of Pittsburgh School of Medicine/University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | - Zhichao Zhang
- College of Life Sciences, Shanxi Agricultural University, Taiyuan, China
| | - Bo Lv
- Aging Institute, University of Pittsburgh School of Medicine/University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | - Defen Lu
- College of Life Sciences, Shanxi Agricultural University, Taiyuan, China
| | - Haoxiang Yang
- Aging Institute, University of Pittsburgh School of Medicine/University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | - Guijun Shang
- College of Life Sciences, Shanxi Agricultural University, Taiyuan, China.
- The Key Laboratory of Medical Molecular Cell Biology of Shanxi Province, Institutes of Biomedical Sciences, Shanxi University, Taiyuan, China.
- Shanxi Provincial Key Laboratory of Protein Structure Determination, SAARI, Taiyuan, China.
| | - Jay Xiaojun Tan
- Aging Institute, University of Pittsburgh School of Medicine/University of Pittsburgh Medical Center, Pittsburgh, PA, USA.
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
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2
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Abstract
The insulin receptor (IR) is a type II receptor tyrosine kinase that plays essential roles in metabolism, growth, and proliferation. Dysregulation of IR signaling is linked to many human diseases, such as diabetes and cancers. The resolution revolution in cryo-electron microscopy has led to the determination of several structures of IR with different numbers of bound insulin molecules in recent years, which have tremendously improved our understanding of how IR is activated by insulin. Here, we review the insulin-induced activation mechanism of IR, including (a) the detailed binding modes and functions of insulin at site 1 and site 2 and (b) the insulin-induced structural transitions that are required for IR activation. We highlight several other key aspects of the activation and regulation of IR signaling and discuss the remaining gaps in our understanding of the IR activation mechanism and potential avenues of future research.
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Affiliation(s)
- Eunhee Choi
- Department of Pathology and Cell Biology, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York, USA;
| | - Xiao-Chen Bai
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, Texas, USA;
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3
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Liu S, Yang B, Hou Y, Cui K, Yang X, Li X, Chen L, Liu S, Zhang Z, Jia Y, Xie Y, Xue Y, Li X, Yan B, Wu C, Deng W, Qi J, Lu D, Gao GF, Wang P, Shang G. The mechanism of STING autoinhibition and activation. Mol Cell 2023; 83:1502-1518.e10. [PMID: 37086726 DOI: 10.1016/j.molcel.2023.03.029] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 10/21/2022] [Accepted: 03/30/2023] [Indexed: 04/24/2023]
Abstract
2',3'-cGAMP, produced by the DNA sensor cGAS, activates stimulator of interferon genes (STING) and triggers immune response during infection. Tremendous effort has been placed on unraveling the mechanism of STING activation. However, little is known about STING inhibition. Here, we found that apo-STING exhibits a bilayer with head-to-head as well as side-by-side packing, mediated by its ligand-binding domain (LBD). This type of assembly holds two endoplasmic reticulum (ER) membranes together not only to prevent STING ER exit but also to eliminate the recruitment of TBK1, representing the autoinhibited state of STING. Additionally, we obtained the filament structure of the STING/2',3'-cGAMP complex, which adopts a bent monolayer assembly mediated by LBD and transmembrane domain (TMD). The active, curved STING polymer could deform ER membrane to support its ER exit and anterograde transportation. Our data together provide a panoramic vision regarding STING autoinhibition and activation, which adds substantially to current understanding of the cGAS-STING pathway.
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Affiliation(s)
- Sheng Liu
- Shanxi Provincial Key Laboratory of Protein Structure Determination, Shanxi Academy of Advanced Research and Innovation, Taiyuan 030012, China; CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China; Cryo-EM Center, Southern University of Science and Technology, Shenzhen 518055, China
| | - Bo Yang
- Shanxi Provincial Key Laboratory of Protein Structure Determination, Shanxi Academy of Advanced Research and Innovation, Taiyuan 030012, China; College of Life Sciences, Shanxi Agricultural University, Taiyuan 030031, China; Shanxi Provincial Key Laboratory for Major Infectious Disease Response, Taiyuan 030012, China
| | - Yingxiang Hou
- Shanxi Provincial Key Laboratory of Protein Structure Determination, Shanxi Academy of Advanced Research and Innovation, Taiyuan 030012, China; The Key Laboratory of Medical Molecular Cell Biology of Shanxi Province, Institutes of Biomedical Sciences, Shanxi University, Taiyuan 030006, China
| | - Kaige Cui
- Shanxi Provincial Key Laboratory of Protein Structure Determination, Shanxi Academy of Advanced Research and Innovation, Taiyuan 030012, China; Shanxi Provincial Key Laboratory for Major Infectious Disease Response, Taiyuan 030012, China
| | - Xiaozhu Yang
- Shanxi Provincial Key Laboratory of Protein Structure Determination, Shanxi Academy of Advanced Research and Innovation, Taiyuan 030012, China; Shanxi Provincial Key Laboratory for Major Infectious Disease Response, Taiyuan 030012, China
| | - Xiaoxiong Li
- Shanxi Provincial Key Laboratory of Protein Structure Determination, Shanxi Academy of Advanced Research and Innovation, Taiyuan 030012, China; Shanxi Provincial Key Laboratory for Major Infectious Disease Response, Taiyuan 030012, China
| | - Lianwan Chen
- National Key Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Shichao Liu
- Shanxi Provincial Key Laboratory of Protein Structure Determination, Shanxi Academy of Advanced Research and Innovation, Taiyuan 030012, China; Shanxi Provincial Key Laboratory for Major Infectious Disease Response, Taiyuan 030012, China
| | - Zhichao Zhang
- Shanxi Provincial Key Laboratory of Protein Structure Determination, Shanxi Academy of Advanced Research and Innovation, Taiyuan 030012, China; Shanxi Provincial Key Laboratory for Major Infectious Disease Response, Taiyuan 030012, China
| | - Yuanyuan Jia
- Shanxi Provincial Key Laboratory of Protein Structure Determination, Shanxi Academy of Advanced Research and Innovation, Taiyuan 030012, China; Shanxi Provincial Key Laboratory for Major Infectious Disease Response, Taiyuan 030012, China
| | - Yufeng Xie
- Shanxi Provincial Key Laboratory of Protein Structure Determination, Shanxi Academy of Advanced Research and Innovation, Taiyuan 030012, China; CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China; Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing 100084, China
| | - Ying Xue
- Shanxi Provincial Key Laboratory of Protein Structure Determination, Shanxi Academy of Advanced Research and Innovation, Taiyuan 030012, China; Shanxi Provincial Key Laboratory for Major Infectious Disease Response, Taiyuan 030012, China
| | - Xiaomei Li
- Shanxi Provincial Key Laboratory of Protein Structure Determination, Shanxi Academy of Advanced Research and Innovation, Taiyuan 030012, China
| | - Bingxue Yan
- Shanxi Provincial Key Laboratory of Protein Structure Determination, Shanxi Academy of Advanced Research and Innovation, Taiyuan 030012, China
| | - Changxin Wu
- The Key Laboratory of Medical Molecular Cell Biology of Shanxi Province, Institutes of Biomedical Sciences, Shanxi University, Taiyuan 030006, China
| | - Wen Deng
- College of Veterinary Medicine, Northwest A&F University, Yangling 712100, China
| | - Jianxun Qi
- CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China; Beijing Life Science Academy, Beijing 102209, China
| | - Defen Lu
- Shanxi Provincial Key Laboratory of Protein Structure Determination, Shanxi Academy of Advanced Research and Innovation, Taiyuan 030012, China; College of Life Sciences, Shanxi Agricultural University, Taiyuan 030031, China.
| | - George F Gao
- Shanxi Provincial Key Laboratory of Protein Structure Determination, Shanxi Academy of Advanced Research and Innovation, Taiyuan 030012, China; CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
| | - Peiyi Wang
- Cryo-EM Center, Southern University of Science and Technology, Shenzhen 518055, China.
| | - Guijun Shang
- Shanxi Provincial Key Laboratory of Protein Structure Determination, Shanxi Academy of Advanced Research and Innovation, Taiyuan 030012, China; College of Life Sciences, Shanxi Agricultural University, Taiyuan 030031, China; Shanxi Provincial Key Laboratory for Major Infectious Disease Response, Taiyuan 030012, China.
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4
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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: 2] [Impact Index Per Article: 2.0] [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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5
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Mun SA, Park J, Kang JY, Park T, Jin M, Yang J, Eom SH. Structural and biochemical insights into Zn 2+-bound EF-hand proteins, EFhd1 and EFhd2. IUCRJ 2023; 10:233-245. [PMID: 36862489 PMCID: PMC9980392 DOI: 10.1107/s2052252523001501] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Accepted: 02/20/2023] [Indexed: 06/18/2023]
Abstract
EF-hand proteins, which contain a Ca2+-binding EF-hand motif, are involved in regulating diverse cellular functions. Ca2+ binding induces conformational changes that modulate the activities of EF-hand proteins. Moreover, these proteins occasionally modify their activities by coordinating metals other than Ca2+, including Mg2+, Pb2+ and Zn2+, within their EF-hands. EFhd1 and EFhd2 are homologous EF-hand proteins with similar structures. Although separately localized within cells, both are actin-binding proteins that modulate F-actin rearrangement through Ca2+-independent actin-binding and Ca2+-dependent actin-bundling activity. Although Ca2+ is known to affect the activities of EFhd1 and EFhd2, it is not known whether their actin-related activities are affected by other metals. Here, the crystal structures of the EFhd1 and EFhd2 core domains coordinating Zn2+ ions within their EF-hands are reported. The presence of Zn2+ within EFhd1 and EFhd2 was confirmed by analyzing anomalous signals and the difference between anomalous signals using data collected at the peak positions as well as low-energy remote positions at the Zn K-edge. EFhd1 and EFhd2 were also found to exhibit Zn2+-independent actin-binding and Zn2+-dependent actin-bundling activity. This suggests the actin-related activities of EFhd1 and EFhd2 could be regulated by Zn2+ as well as Ca2+.
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Affiliation(s)
- Sang A Mun
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
- Steitz Center for Structural Biology, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
| | - Jongseo Park
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
- Steitz Center for Structural Biology, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
| | - Jung Youn Kang
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
- Steitz Center for Structural Biology, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
| | - Taein Park
- Steitz Center for Structural Biology, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
- Department of Chemistry, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
| | - Minwoo Jin
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
- Steitz Center for Structural Biology, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
| | - Jihyeong Yang
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
- Steitz Center for Structural Biology, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
| | - Soo Hyun Eom
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
- Steitz Center for Structural Biology, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
- Department of Chemistry, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
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6
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González-Magaña A, Altuna J, Queralt-Martín M, Largo E, Velázquez C, Montánchez I, Bernal P, Alcaraz A, Albesa-Jové D. The P. aeruginosa effector Tse5 forms membrane pores disrupting the membrane potential of intoxicated bacteria. Commun Biol 2022; 5:1189. [PMID: 36335275 PMCID: PMC9637101 DOI: 10.1038/s42003-022-04140-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Accepted: 10/20/2022] [Indexed: 11/08/2022] Open
Abstract
The type VI secretion system (T6SS) of Pseudomonas aeruginosa injects effector proteins into neighbouring competitors and host cells, providing a fitness advantage that allows this opportunistic nosocomial pathogen to persist and prevail during the onset of infections. However, despite the high clinical relevance of P. aeruginosa, the identity and mode of action of most P. aeruginosa T6SS-dependent effectors remain to be discovered. Here, we report the molecular mechanism of Tse5-CT, the toxic auto-proteolytic product of the P. aeruginosa T6SS exported effector Tse5. Our results demonstrate that Tse5-CT is a pore-forming toxin that can transport ions across the membrane, causing membrane depolarisation and bacterial death. The membrane potential regulates a wide range of essential cellular functions; therefore, membrane depolarisation is an efficient strategy to compete with other microorganisms in polymicrobial environments. The Pseudomonas aeruginosa Type 6 secretion effector Tse5 forms pores in the cytoplasmic membrane when ectopically produced and hence has a bacteriolytic effect by depolarising the inner membrane potential.
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Affiliation(s)
- Amaia González-Magaña
- Fundación Biofísica Bizkaia/Biofisika Bizkaia Fundazioa (FBB) and Departamento de Bioquímica y Biología Molecular, Instituto Biofisika (CSIC, UPV/EHU), University of the Basque Country, 48940, Leioa, Spain
| | - Jon Altuna
- Fundación Biofísica Bizkaia/Biofisika Bizkaia Fundazioa (FBB) and Departamento de Bioquímica y Biología Molecular, Instituto Biofisika (CSIC, UPV/EHU), University of the Basque Country, 48940, Leioa, Spain
| | - María Queralt-Martín
- Laboratory of Molecular Biophysics, Department of Physics, University Jaume I, 12071, Castellón, Spain
| | - Eneko Largo
- Fundación Biofísica Bizkaia/Biofisika Bizkaia Fundazioa (FBB) and Departamento de Bioquímica y Biología Molecular, Instituto Biofisika (CSIC, UPV/EHU), University of the Basque Country, 48940, Leioa, Spain.,Departamento de Inmunología, Microbiología y Parasitología, University of the Basque Country, 48940, Leioa, Spain
| | - Carmen Velázquez
- Fundación Biofísica Bizkaia/Biofisika Bizkaia Fundazioa (FBB) and Departamento de Bioquímica y Biología Molecular, Instituto Biofisika (CSIC, UPV/EHU), University of the Basque Country, 48940, Leioa, Spain
| | - Itxaso Montánchez
- Departamento de Inmunología, Microbiología y Parasitología, University of the Basque Country, 48940, Leioa, Spain
| | - Patricia Bernal
- Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, 41012, Sevilla, Spain
| | - Antonio Alcaraz
- Laboratory of Molecular Biophysics, Department of Physics, University Jaume I, 12071, Castellón, Spain
| | - David Albesa-Jové
- Fundación Biofísica Bizkaia/Biofisika Bizkaia Fundazioa (FBB) and Departamento de Bioquímica y Biología Molecular, Instituto Biofisika (CSIC, UPV/EHU), University of the Basque Country, 48940, Leioa, Spain. .,Ikerbasque, Basque Foundation for Science, 48013, Bilbao, Spain.
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7
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Qin S, Xiao W, Zhou C, Pu Q, Deng X, Lan L, Liang H, Song X, Wu M. Pseudomonas aeruginosa: pathogenesis, virulence factors, antibiotic resistance, interaction with host, technology advances and emerging therapeutics. Signal Transduct Target Ther 2022; 7:199. [PMID: 35752612 PMCID: PMC9233671 DOI: 10.1038/s41392-022-01056-1] [Citation(s) in RCA: 271] [Impact Index Per Article: 135.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 06/04/2022] [Accepted: 06/08/2022] [Indexed: 02/05/2023] Open
Abstract
Pseudomonas aeruginosa (P. aeruginosa) is a Gram-negative opportunistic pathogen that infects patients with cystic fibrosis, burn wounds, immunodeficiency, chronic obstructive pulmonary disorder (COPD), cancer, and severe infection requiring ventilation, such as COVID-19. P. aeruginosa is also a widely-used model bacterium for all biological areas. In addition to continued, intense efforts in understanding bacterial pathogenesis of P. aeruginosa including virulence factors (LPS, quorum sensing, two-component systems, 6 type secretion systems, outer membrane vesicles (OMVs), CRISPR-Cas and their regulation), rapid progress has been made in further studying host-pathogen interaction, particularly host immune networks involving autophagy, inflammasome, non-coding RNAs, cGAS, etc. Furthermore, numerous technologic advances, such as bioinformatics, metabolomics, scRNA-seq, nanoparticles, drug screening, and phage therapy, have been used to improve our understanding of P. aeruginosa pathogenesis and host defense. Nevertheless, much remains to be uncovered about interactions between P. aeruginosa and host immune responses, including mechanisms of drug resistance by known or unannotated bacterial virulence factors as well as mammalian cell signaling pathways. The widespread use of antibiotics and the slow development of effective antimicrobials present daunting challenges and necessitate new theoretical and practical platforms to screen and develop mechanism-tested novel drugs to treat intractable infections, especially those caused by multi-drug resistance strains. Benefited from has advancing in research tools and technology, dissecting this pathogen's feature has entered into molecular and mechanistic details as well as dynamic and holistic views. Herein, we comprehensively review the progress and discuss the current status of P. aeruginosa biophysical traits, behaviors, virulence factors, invasive regulators, and host defense patterns against its infection, which point out new directions for future investigation and add to the design of novel and/or alternative therapeutics to combat this clinically significant pathogen.
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Affiliation(s)
- Shugang Qin
- Department of Critical Care Medicine, Frontiers Science Center for Disease-related Molecular Network, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, China
| | - Wen Xiao
- Department of Critical Care Medicine, Frontiers Science Center for Disease-related Molecular Network, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, China
| | - Chuanmin Zhou
- State Key Laboratory of Virology, School of Public Health, Wuhan University, Wuhan, 430071, P.R. China
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND, 58203, USA
| | - Qinqin Pu
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND, 58203, USA
| | - Xin Deng
- Department of Biomedical Sciences, City University of Hong Kong, Hong Kong, People's Republic of China
| | - Lefu Lan
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
| | - Haihua Liang
- College of Life Sciences, Northwest University, Xi'an, ShaanXi, 710069, China
| | - Xiangrong Song
- Department of Critical Care Medicine, Frontiers Science Center for Disease-related Molecular Network, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, China.
| | - Min Wu
- Department of Critical Care Medicine, Frontiers Science Center for Disease-related Molecular Network, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, China.
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND, 58203, USA.
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8
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Wen H, Liu G, Geng Z, Zhang H, Li Y, She Z, Dong Y. Structure and SAXS studies unveiled a novel inhibition mechanism of the Pseudomonas aeruginosa T6SS TseT-TsiT complex. Int J Biol Macromol 2021; 188:450-459. [PMID: 34371041 DOI: 10.1016/j.ijbiomac.2021.08.029] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 07/20/2021] [Accepted: 08/04/2021] [Indexed: 02/05/2023]
Abstract
The bacterial type VI secretion system (T6SS) is a powerful arsenal that fires many toxic effectors into neighboring cells to gain advantage over inter-bacterial competition and eukaryotic host infection. Meanwhile, the cognate immunity proteins of these effectors are employed to protect themselves from the virulence. TseT-TsiT is a newly discovered effector-immunity (E-I) protein pair secreted by T6SS of Pseudomonas aeruginosa. Our group had reported the crystal structure of TsiT before. Here, we report the crystal structure of P. aeruginosa TseT-TsiT complex at 3.1 Å resolution. The interface of TseT-TsiT is characterized in this work. Through structure and small angle X-ray scattering (SAXS) studies, we discover that the long C-terminal helix of TseT may be flexible. Combining the homolog comparison results, we propose that TseT may form an oligomer in favor of its putative nuclease activity. Although TsiT doesn't directly block the putative active-site of TseT, it may hinder the TseT's oligomerization process to neutralize its virulence.
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Affiliation(s)
- Haiying Wen
- Key Laboratory of Structural Biology, School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Guangfeng Liu
- National Center for Protein Science Shanghai, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, China
| | - Zhi Geng
- Multidiscipline Research Center, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China
| | - Heng Zhang
- Multidiscipline Research Center, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China
| | - Yanhua Li
- Multidiscipline Research Center, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China
| | - Zhun She
- Multidiscipline Research Center, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China.
| | - Yuhui Dong
- Multidiscipline Research Center, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, China.
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9
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González-Magaña A, Sainz-Polo MÁ, Pretre G, Çapuni R, Lucas M, Altuna J, Montánchez I, Fucini P, Albesa-Jové D. Structural insights into Pseudomonas aeruginosaType six secretion system exported effector 8. J Struct Biol 2020; 212:107651. [PMID: 33096229 DOI: 10.1016/j.jsb.2020.107651] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 10/13/2020] [Accepted: 10/15/2020] [Indexed: 12/24/2022]
Abstract
Recent reports indicate that the Type six secretion system exported effector 8 (Tse8) is a cytoactive effector secreted by the Type VI secretion system (T6SS) of the human pathogen Pseudomonas aeruginosa. The T6SS is a nanomachine that assembles inside of the bacteria and injects effectors/toxins into target cells, providing a fitness advantage over competing bacteria and facilitating host colonisation. Here we present the first crystal structure of Tse8 revealing that it conserves the architecture of the catalytic triad Lys84-transSer162-Ser186 that characterises members of the Amidase Signature superfamily. Furthermore, using binding affinity experiments, we show that the interaction of phenylmethylsulfonyl fluoride (PMSF) to Tse8 is dependent on the putative catalytic residue Ser186, providing support for its nucleophilic reactivity. This work thus demonstrates that Tse8 belongs to the Amidase Signature (AS) superfamily. Furthermore, it highlights Tse8 similarity to two family members: the Stenotrophomonas maltophilia Peptide Amidase and the Glutamyl-tRNAGln amidotransferase subunit A from Staphylococcus aureus.
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Affiliation(s)
- Amaia González-Magaña
- Instituto Biofisika (UPV/EHU, CSIC), Fundación Biofísica Bizkaia/Biofisika Bizkaia Fundazioa (FBB) and Departamento de Bioquímica y Biología Molecular, University of the Basque Country, 48940 Leioa, Spain
| | - M Ángela Sainz-Polo
- Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, 48160 Derio, Spain
| | - Gabriela Pretre
- Instituto Biofisika (UPV/EHU, CSIC), Fundación Biofísica Bizkaia/Biofisika Bizkaia Fundazioa (FBB) and Departamento de Bioquímica y Biología Molecular, University of the Basque Country, 48940 Leioa, Spain
| | - Retina Çapuni
- Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, 48160 Derio, Spain
| | - María Lucas
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Consejo Superior de Investigaciones Científicas (CSIC)-Universidad de Cantabria. Santander, 39011 Cantabria, Spain
| | - Jon Altuna
- Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, 48160 Derio, Spain
| | - Itxaso Montánchez
- Departamento de Inmunología, Microbiología y Parasitología, University of the Basque Country, 48940 Leioa, Spain
| | - Paola Fucini
- Ikerbasque, Basque Foundation for Science, 48013 Bilbao, Spain
| | - David Albesa-Jové
- Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, 48160 Derio, Spain; Ikerbasque, Basque Foundation for Science, 48013 Bilbao, Spain.
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10
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Grishin AV, Karyagina AS, Vasina DV, Vasina IV, Gushchin VA, Lunin VG. Resistance to peptidoglycan-degrading enzymes. Crit Rev Microbiol 2020; 46:703-726. [PMID: 32985279 DOI: 10.1080/1040841x.2020.1825333] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The spread of bacterial strains resistant to commonly used antibiotics urges the development of novel antibacterial compounds. Ideally, these novel antimicrobials should be less prone to the development of resistance. Peptidoglycan-degrading enzymes are a promising class of compounds with a fundamentally different mode of action compared to traditionally used antibiotics. The difference in the mechanism of action implies differences both in the mechanisms of resistance and the chances of its emergence. To critically assess the potential of resistance development to peptidoglycan-degrading enzymes, we review the available evidence for the development of resistance to these enzymes in vitro, along with the known mechanisms of resistance to lysozyme, bacteriocins, autolysins, and phage endolysins. We conclude that genetic determinants of resistance to peptidoglycan-degrading enzymes are unlikely to readily emerge de novo. However, resistance to these enzymes would probably spread by the horizontal transfer between intrinsically resistant and susceptible species. Finally, we speculate that the higher cost of the therapeutics based on peptidoglycan degrading enzymes compared to classical antibiotics might result in less misuse, which in turn would lead to lower selective pressure, making these antibacterials less prone to resistance development.
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Affiliation(s)
- Alexander V Grishin
- N.F. Gamaleya National Research Center for Epidemiology and Microbiology, Ministry of Health of the Russian Federation, Moscow, Russia.,All-Russia Research Institute of Agricultural Biotechnology, Russian Academy of Sciences, Moscow, Russia
| | - Anna S Karyagina
- N.F. Gamaleya National Research Center for Epidemiology and Microbiology, Ministry of Health of the Russian Federation, Moscow, Russia.,All-Russia Research Institute of Agricultural Biotechnology, Russian Academy of Sciences, Moscow, Russia.,A.N. Belozersky Institute of Physical and Chemical Biology, M.V. Lomonosov Moscow State University, Moscow, Russia
| | - Daria V Vasina
- N.F. Gamaleya National Research Center for Epidemiology and Microbiology, Ministry of Health of the Russian Federation, Moscow, Russia.,A.N. Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Moscow, Russia
| | - Irina V Vasina
- N.F. Gamaleya National Research Center for Epidemiology and Microbiology, Ministry of Health of the Russian Federation, Moscow, Russia
| | - Vladimir A Gushchin
- N.F. Gamaleya National Research Center for Epidemiology and Microbiology, Ministry of Health of the Russian Federation, Moscow, Russia.,Faculty of Biology, M.V. Lomonosov Moscow State University, Moscow, Russia
| | - Vladimir G Lunin
- N.F. Gamaleya National Research Center for Epidemiology and Microbiology, Ministry of Health of the Russian Federation, Moscow, Russia.,All-Russia Research Institute of Agricultural Biotechnology, Russian Academy of Sciences, Moscow, Russia
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11
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Kuo YC, Chen H, Shang G, Uchikawa E, Tian H, Bai XC, Zhang X. Cryo-EM structure of the PlexinC1/A39R complex reveals inter-domain interactions critical for ligand-induced activation. Nat Commun 2020; 11:1953. [PMID: 32327662 PMCID: PMC7181871 DOI: 10.1038/s41467-020-15862-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 04/01/2020] [Indexed: 11/09/2022] Open
Abstract
Plexins are receptors for semaphorins that transduce signals for regulating neuronal development and other processes. Plexins are single-pass transmembrane proteins with multiple domains in both the extracellular and intracellular regions. Semaphorin activates plexin by binding to its extracellular N-terminal Sema domain, inducing the active dimer of the plexin intracellular region. The mechanism underlying this activation process of plexin is incompletely understood. We present cryo-electron microscopic structure of full-length human PlexinC1 in complex with the viral semaphorin mimic A39R. The structure shows that A39R induces a specific dimer of PlexinC1 where the membrane-proximal domains from the two PlexinC1 protomers are placed close to each other, poised to promote the active dimer of the intracellular region. This configuration is imposed by a distinct conformation of the PlexinC1 extracellular region, stabilized by inter-domain interactions among the Sema and membrane-proximal domains. Our mutational analyses support the critical role of this conformation in PlexinC1 activation. Plexins are the receptors for the guidance molecules semaphorins and regulate immunity and the development of the nervous and cardiovascular systems. Here authors present a structure of full-length human PlexinC1 in complex with its ligand A39R, which reveals how inter-domain interactions couple extracellular ligand binding to receptor activation and signaling.
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Affiliation(s)
- Yi-Chun Kuo
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Hua Chen
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Guijun Shang
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Emiko Uchikawa
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Hui Tian
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Xiao-Chen Bai
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA. .,Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
| | - Xuewu Zhang
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, USA. .,Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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12
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Klein TA, Ahmad S, Whitney JC. Contact-Dependent Interbacterial Antagonism Mediated by Protein Secretion Machines. Trends Microbiol 2020; 28:387-400. [PMID: 32298616 DOI: 10.1016/j.tim.2020.01.003] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Revised: 12/18/2019] [Accepted: 01/16/2020] [Indexed: 12/29/2022]
Abstract
To establish and maintain an ecological niche, bacteria employ a wide range of pathways to inhibit the growth of their microbial competitors. Some of these pathways, such as those that produce antibiotics or bacteriocins, exert toxicity on nearby cells in a cell contact-independent manner. More recently, however, several mechanisms of interbacterial antagonism requiring cell-to-cell contact have been identified. This form of microbial competition is mediated by antibacterial protein toxins whose delivery to target bacteria uses protein secretion apparatuses embedded within the cell envelope of toxin-producing bacteria. In this review, we discuss recent work implicating the bacterial Type I, IV, VI, and VII secretion systems in the export of antibacterial 'effector' proteins that mediate contact-dependent interbacterial antagonism.
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Affiliation(s)
- Timothy A Klein
- Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON, Canada L8S 4K1; Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada L8S 4K1
| | - Shehryar Ahmad
- Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON, Canada L8S 4K1; Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada L8S 4K1
| | - John C Whitney
- Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON, Canada L8S 4K1; Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada L8S 4K1; David Braley Centre for Antibiotic Discovery, McMaster University, Hamilton, ON, Canada L8S 4K1.
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13
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Li J, Choi E, Yu H, Bai XC. Structural basis of the activation of type 1 insulin-like growth factor receptor. Nat Commun 2019; 10:4567. [PMID: 31594955 PMCID: PMC6783537 DOI: 10.1038/s41467-019-12564-0] [Citation(s) in RCA: 100] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 09/10/2019] [Indexed: 11/09/2022] Open
Abstract
Type 1 insulin-like growth factor receptor (IGF1R) is a receptor tyrosine kinase that regulates cell growth and proliferation, and can be activated by IGF1, IGF2, and insulin. Here, we report the cryo-EM structure of full-length IGF1R–IGF1 complex in the active state. This structure reveals that only one IGF1 molecule binds the Γ-shaped asymmetric IGF1R dimer. The IGF1-binding site is formed by the L1 and CR domains of one IGF1R protomer and the α-CT and FnIII-1 domains of the other. The liganded α-CT forms a rigid beam-like structure with the unliganded α-CT, which hinders the conformational change of the unliganded α-CT required for binding of a second IGF1 molecule. We further identify an L1–FnIII-2 interaction that mediates the dimerization of membrane-proximal domains of IGF1R. This interaction is required for optimal receptor activation. Our study identifies a source of the negative cooperativity in IGF1 binding to IGF1R and reveals the structural basis of IGF1R activation. The activation mechanism of type 1 insulin-like growth factor receptor (IGF1R) is not fully understood. Here, the authors determine the cryo-EM structure of full-length, IGF1-bound IGF1R in the active conformation, providing insights into how IGF1 triggers receptor activation.
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Affiliation(s)
- Jie Li
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Eunhee Choi
- Howard Hughes Medical Institute, Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
| | - Hongtao Yu
- Howard Hughes Medical Institute, Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
| | - Xiao-Chen Bai
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA. .,Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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14
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Uchikawa E, Choi E, Shang G, Yu H, Bai XC. Activation mechanism of the insulin receptor revealed by cryo-EM structure of the fully liganded receptor-ligand complex. eLife 2019; 8:e48630. [PMID: 31436533 PMCID: PMC6721835 DOI: 10.7554/elife.48630] [Citation(s) in RCA: 103] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 08/21/2019] [Indexed: 12/12/2022] Open
Abstract
Insulin signaling controls metabolic homeostasis. Here, we report the cryo-EM structure of full-length insulin receptor (IR) and insulin complex in the active state. This structure unexpectedly reveals that maximally four insulins can bind the 'T'-shaped IR dimer at four distinct sites related by 2-fold symmetry. Insulins 1 and 1' bind to sites 1 and 1', formed by L1 of one IR protomer and α-CT and FnIII-1 of the other. Insulins 2 and 2' bind to sites 2 and 2' on FnIII-1 of each protomer. Mutagenesis and cellular assays show that both sites 1 and 2 are required for optimal insulin binding and IR activation. We further identify a homotypic FnIII-2-FnIII-2 interaction in mediating the dimerization of membrane proximal domains in the active IR dimer. Our results indicate that binding of multiple insulins at two distinct types of sites disrupts the autoinhibited apo-IR dimer and stabilizes the active dimer.
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Affiliation(s)
- Emiko Uchikawa
- Department of BiophysicsUniversity of Texas Southwestern Medical CenterDallasUnited States
| | - Eunhee Choi
- Department of PharmacologyHoward Hughes Medical Institute, University of Texas Southwestern Medical CenterDallasUnited States
| | - Guijun Shang
- Department of PharmacologyUniversity of Texas Southwestern Medical CenterDallasUnited States
| | - Hongtao Yu
- Department of PharmacologyHoward Hughes Medical Institute, University of Texas Southwestern Medical CenterDallasUnited States
| | - Xiao-chen Bai
- Department of BiophysicsUniversity of Texas Southwestern Medical CenterDallasUnited States
- Department of Cell BiologyUniversity of Texas Southwestern Medical CenterDallasUnited States
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15
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She Z, Geng Z, Xu JH, Li YH, Dong YH. Structural characterization of the Imm52 family protein TsiT in Pseudomonas aeruginosa. Protein Sci 2019; 28:971-975. [PMID: 30834616 DOI: 10.1002/pro.3597] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Accepted: 02/26/2019] [Indexed: 11/08/2022]
Abstract
The bacterial type VI secretion system (T6SS) utilizes many toxic effectors to gain advantage over interbacterial competition and eukaryotic host infection. Meanwhile, the cognate immunity proteins of these effectors are employed to protect themselves from the virulence. TseT and TsiT form an effector-immunity (E-I) protein pair secreted by T6SS of Pseudomonas aeruginosa. TseT is toxic for other bacteria, whereas TsiT can suppress the virulence of TseT. Here, we report the crystal structure of TsiT at 1.6 Å resolution. TsiT is a typical α + β class protein and belongs to a novel Imm52 protein family of the polymorphic toxin system. Apart from TsiT, only one structure of the Imm52 family proteins is present in the Protein Data Bank (PDB), but that structure is not characterized and shares low sequence identity with TsiT. We characterized the basic features of TsiT structure and identified conserved residues of the Imm52 family proteins according to homology comparison. Our work provided structural information of a new protein family and should aid future functional studies.
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Affiliation(s)
- Zhun She
- Multidiscipline Research Center, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
| | - Zhi Geng
- Multidiscipline Research Center, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
| | - Jian-Hua Xu
- Multidiscipline Research Center, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
| | - Yan-Hua Li
- Multidiscipline Research Center, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
| | - Yu-Hui Dong
- Multidiscipline Research Center, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
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16
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Structural basis of STING binding with and phosphorylation by TBK1. Nature 2019; 567:394-398. [PMID: 30842653 DOI: 10.1038/s41586-019-1000-2] [Citation(s) in RCA: 544] [Impact Index Per Article: 108.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Accepted: 02/07/2019] [Indexed: 11/08/2022]
Abstract
The invasion of mammalian cytoplasm by microbial DNA from infectious pathogens or by self DNA from the nucleus or mitochondria represents a danger signal that alerts the host immune system1. Cyclic GMP-AMP synthase (cGAS) is a sensor of cytoplasmic DNA that activates the type-I interferon pathway2. On binding to DNA, cGAS is activated to catalyse the synthesis of cyclic GMP-AMP (cGAMP) from GTP and ATP3. cGAMP functions as a second messenger that binds to and activates stimulator of interferon genes (STING)3-9. STING then recruits and activates tank-binding kinase 1 (TBK1), which phosphorylates STING and the transcription factor IRF3 to induce type-I interferons and other cytokines10,11. However, how cGAMP-bound STING activates TBK1 and IRF3 is not understood. Here we present the cryo-electron microscopy structure of human TBK1 in complex with cGAMP-bound, full-length chicken STING. The structure reveals that the C-terminal tail of STING adopts a β-strand-like conformation and inserts into a groove between the kinase domain of one TBK1 subunit and the scaffold and dimerization domain of the second subunit in the TBK1 dimer. In this binding mode, the phosphorylation site Ser366 in the STING tail cannot reach the kinase-domain active site of bound TBK1, which suggests that STING phosphorylation by TBK1 requires the oligomerization of both proteins. Mutational analyses validate the interaction mode between TBK1 and STING and support a model in which high-order oligomerization of STING and TBK1, induced by cGAMP, leads to STING phosphorylation by TBK1.
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17
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Cryo-EM structures of STING reveal its mechanism of activation by cyclic GMP-AMP. Nature 2019; 567:389-393. [PMID: 30842659 DOI: 10.1038/s41586-019-0998-5] [Citation(s) in RCA: 394] [Impact Index Per Article: 78.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Accepted: 02/12/2019] [Indexed: 12/25/2022]
Abstract
Infections by pathogens that contain DNA trigger the production of type-I interferons and inflammatory cytokines through cyclic GMP-AMP synthase, which produces 2'3'-cyclic GMP-AMP (cGAMP) that binds to and activates stimulator of interferon genes (STING; also known as TMEM173, MITA, ERIS and MPYS)1-8. STING is an endoplasmic-reticulum membrane protein that contains four transmembrane helices followed by a cytoplasmic ligand-binding and signalling domain9-13. The cytoplasmic domain of STING forms a dimer, which undergoes a conformational change upon binding to cGAMP9,14. However, it remains unclear how this conformational change leads to STING activation. Here we present cryo-electron microscopy structures of full-length STING from human and chicken in the inactive dimeric state (about 80 kDa in size), as well as cGAMP-bound chicken STING in both the dimeric and tetrameric states. The structures show that the transmembrane and cytoplasmic regions interact to form an integrated, domain-swapped dimeric assembly. Closure of the ligand-binding domain, induced by cGAMP, leads to a 180° rotation of the ligand-binding domain relative to the transmembrane domain. This rotation is coupled to a conformational change in a loop on the side of the ligand-binding-domain dimer, which leads to the formation of the STING tetramer and higher-order oligomers through side-by-side packing. This model of STING oligomerization and activation is supported by our structure-based mutational analyses.
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18
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Effector⁻Immunity Pairs Provide the T6SS Nanomachine its Offensive and Defensive Capabilities. Molecules 2018; 23:molecules23051009. [PMID: 29701633 PMCID: PMC6099711 DOI: 10.3390/molecules23051009] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 04/13/2018] [Accepted: 04/23/2018] [Indexed: 01/23/2023] Open
Abstract
Type VI protein secretion systems (T6SSs) are specialized transport apparatus which can target both eukaryotic and prokaryotic cells and play key roles in host⁻pathogen⁻microbiota interactions. Therefore, T6SSs have attracted much attention as a research topic during the past ten years. In this review, we particularly summarized the T6SS antibacterial function, which involves an interesting offensive and defensive mechanism of the effector⁻immunity (E⁻I) pairs. The three main categories of effectors that target the cell wall, membranes, and nucleic acids during bacterial interaction, along with their corresponding immunity proteins are presented. We also discuss structural analyses of several effectors and E⁻I pairs, which explain the offensive and defensive mechanisms underpinning T6SS function during bacterial competition for niche-space, as well as the bioinformatics, proteomics, and protein⁻protein interaction (PPI) methods used to identify and characterize T6SS mediated E⁻I pairs. Additionally, we described PPI methods for verifying E⁻I pairs.
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19
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Structure of the calcium-dependent type 2 secretion pseudopilus. Nat Microbiol 2017; 2:1686-1695. [PMID: 28993624 PMCID: PMC5705324 DOI: 10.1038/s41564-017-0041-2] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Accepted: 09/11/2017] [Indexed: 11/08/2022]
Abstract
Many Gram-negative bacteria use type 2 secretion systems (T2SS) to secrete proteins involved in virulence and adaptation. Transport of folded proteins via T2SS nanomachines requires the assembly of inner membrane-anchored fibers called pseudopili. Although efficient pseudopilus assembly is essential for protein secretion, structure-based functional analyses are required to unravel the mechanistic link between these processes. Here, we report an atomic model for a T2SS pseudopilus from Klebsiella oxytoca, obtained by fitting the NMR structure of its calcium-bound subunit PulG into the ~ 5 Å resolution cryo-electron microscopy (cryoEM) reconstruction of assembled fibers. This structure reveals the comprehensive network of inter-subunit contacts and unexpected features, including a disordered central region of the PulG helical stem, and highly flexible C-terminal residues on the fiber surface. NMR, mutagenesis and functional analyses highlight the key role of calcium in PulG folding and stability. Fiber disassembly in the absence of calcium provides a basis for pseudopilus length control, essential for protein secretion, and supports the Archimedes' screw model for T2S mechanism.
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20
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Yang XY, Li ZQ, Gao ZQ, Wang WJ, Geng Z, Xu JH, She Z, Dong YH. Structural and SAXS analysis of Tle5-Tli5 complex reveals a novel inhibition mechanism of H2-T6SS in Pseudomonas aeruginosa. Protein Sci 2017; 26:2083-2091. [PMID: 28758353 DOI: 10.1002/pro.3246] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Revised: 07/17/2017] [Accepted: 07/17/2017] [Indexed: 11/11/2022]
Abstract
Widely spread in Gram-negative bacteria, the type VI secretion system (T6SS) secretes many effector-immunity protein pairs to help the bacteria compete against other prokaryotic rivals, and infect their eukaryotic hosts. Tle5 and Tle5B are two phospholipase effector protein secreted by T6SS of Pseudomonas aeruginosa. They can facilitate the bacterial internalization process into human epithelial cells by interacting with Akt protein of the PI3K-Akt signal pathway. Tli5 and PA5086-5088 are cognate immunity proteins of Tle5 and Tle5B, respectively. They can interact with their cognate effector proteins to suppress their virulence. Here, we report the crystal structure of Tli5 at 2.8Å resolution and successfully fit it into the Small angle X-ray scattering (SAXS) model of the complete Tle5-Tli5 complex. We identified two important motifs in Tli5 through sequence and structural analysis. One is a conserved loop-β-hairpin motif that exists in the Tle5 immunity homologs, the other is a long and sharp α-α motif that directly interacts with Tle5 according to SAXS data. We also distinguished the structural features of Tle5 and Tle5B family immunity proteins. Together, our work provided insights into a novel inhibition mechanism that may enhance our understanding of phospholipase D family proteins.
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Affiliation(s)
- Xiao-Yun Yang
- Key Laboratory of Structural Biology, School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Zong-Qiang Li
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Zeng-Qiang Gao
- Multidiscipline Research Center, Institute of High Energy Physics Chinese Academy of Sciences, Beijing, China
| | - Wen-Jia Wang
- Department of Optoelectronic Information, School of Science, Qilu University of Technology, Jinan, China
| | - Zhi Geng
- Multidiscipline Research Center, Institute of High Energy Physics Chinese Academy of Sciences, Beijing, China
| | - Jian-Hua Xu
- Multidiscipline Research Center, Institute of High Energy Physics Chinese Academy of Sciences, Beijing, China
| | - Zhun She
- Multidiscipline Research Center, Institute of High Energy Physics Chinese Academy of Sciences, Beijing, China
| | - Yu-Hui Dong
- Multidiscipline Research Center, Institute of High Energy Physics Chinese Academy of Sciences, Beijing, China
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21
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Abstract
The versatile and ubiquitous
Pseudomonas aeruginosa is an opportunistic pathogen causing acute and chronic infections in predisposed human subjects. Here we review recent progress in understanding
P. aeruginosa population biology and virulence, its cyclic di-GMP-mediated switches of lifestyle, and its interaction with the mammalian host as well as the role of the type III and type VI secretion systems in
P. aeruginosa infection.
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Affiliation(s)
- Jens Klockgether
- Molecular Pathology of Cystic Fibrosis Clinical Research Group, Clinic for Paediatric Pneumology, Allergology, and Neonatology, OE 6710, Hannover Medical School, Hannover, Germany
| | - Burkhard Tümmler
- Molecular Pathology of Cystic Fibrosis Clinical Research Group, Clinic for Paediatric Pneumology, Allergology, and Neonatology, OE 6710, Hannover Medical School, Hannover, Germany.,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Member of the German Centre for Lung Research, Hannover, Germany
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22
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Fernandez MP, Garcia M, Martin-Almedina S, Morgan RO. Novel domain architectures and functional determinants in atypical annexins revealed by phylogenomic analysis. Biol Chem 2017; 398:751-763. [PMID: 28002020 DOI: 10.1515/hsz-2016-0273] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2016] [Accepted: 12/11/2016] [Indexed: 01/27/2023]
Abstract
The fundamental cellular role and molecular interactions of annexins in vesicle trafficking and membrane remodeling remain to be further clarified in order to better understand and exploit their contributions to health and disease. We focused on distinctive features of atypical annexins from all domains of life using phylogenomic, molecular systematic and experimental approaches, to extend the current paradigm and better account for annexin diversity of structure, function and mechanistic role in membrane homeostasis. The analysis of gene duplications, organization of domain architectures and profile hidden Markov models of subfamily orthologs defined conserved structural features relevant to molecular interactions and functional divergence of seven family clades ANXA-G. Single domain annexins of bacteria, including cyanobacteria, were frequently coupled to enzymatic units conceivably related to membrane metabolism and remodeling. Multiple ANX domains (up to 20) and various distinct functional domains were observed in unique annexins. Canonical type 2 calcium binding ligands were well-preserved in roughly half of all ANX domains, but alternative structural motifs comprised of 'KGD', cysteine or tryptophan residues were prominently conserved in the same strategic interhelical loops. Selective evolutionary constraint, site-specific location and co-occurrence in all kingdoms identify alternative modes of fundamental binding interactions for annexins.
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23
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Humbert MV, Awanye AM, Lian LY, Derrick JP, Christodoulides M. Structure of the Neisseria Adhesin Complex Protein (ACP) and its role as a novel lysozyme inhibitor. PLoS Pathog 2017; 13:e1006448. [PMID: 28662181 PMCID: PMC5507604 DOI: 10.1371/journal.ppat.1006448] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 07/12/2017] [Accepted: 06/06/2017] [Indexed: 12/12/2022] Open
Abstract
Pathogenic and commensal Neisseria species produce an Adhesin Complex Protein, which was first characterised in Neisseria meningitidis (Nm) as a novel surface-exposed adhesin with vaccine potential. In the current study, the crystal structure of a recombinant (r)Nm-ACP Type I protein was determined to 1.4 Å resolution: the fold resembles an eight-stranded β-barrel, stabilized by a disulphide bond between the first (Cys38) and last (Cys121) β-strands. There are few main-chain hydrogen bonds linking β4-β5 and β8-β1, so the structure divides into two four-stranded anti-parallel β-sheets (β1-β4 and β5-β8). The computed surface electrostatic charge distribution showed that the β1-β4 sheet face is predominantly basic, whereas the β5-β8 sheet is apolar, apart from the loop between β4 and β5. Concentrations of rNm-ACP and rNeisseria gonorrhoeae-ACP proteins ≥0.25 μg/ml significantly inhibited by ~80–100% (P<0.05) the in vitro activity of human lysozyme (HL) over 24 h. Specificity was demonstrated by the ability of murine anti-Neisseria ACP sera to block ACP inhibition and restore HL activity. ACP expression conferred tolerance to HL activity, as demonstrated by significant 3–9 fold reductions (P<0.05) in the growth of meningococcal and gonococcal acp gene knock-out mutants in the presence of lysozyme. In addition, wild-type Neisseria lactamica treated with purified ACP-specific rabbit IgG antibodies showed similar fold reductions in bacterial growth, compared with untreated bacteria (P<0.05). Nm-ACPI is structurally similar to the MliC/PliC protein family of lysozyme inhibitors. However, Neisseria ACP proteins show <20% primary sequence similarity with these inhibitors and do not share any conserved MliC/PliC sequence motifs associated with lysozyme recognition. These observations suggest that Neisseria ACP adopts a different mode of lysozyme inhibition and that the ability of ACP to inhibit lysozyme activity could be important for host colonization by both pathogenic and commensal Neisseria organisms. Thus, ACP represents a dual target for developing Neisseria vaccines and drugs to inhibit host-pathogen interactions. The genus Neisseria contains two major human pathogens: N. meningitidis (Nm) causes meningitis and sepsis, and N. gonorrhoeae (Ng) causes the sexually transmitted disease gonorrhoea. In addition, the genus contains a larger number of commensal organisms, including N. lactamica (Nl). Common to all of these organisms is the ability to colonize exposed mucosal epithelia. Recently, we identified a novel surface-exposed adhesin in Neisseria spp., the Adhesin Complex Protein (ACP), which was capable also of generating a functional bactericidal antibody response in mice. In the current study, we have determined the crystal structure of a recombinant (r)Nm-ACP and shown that it shares structural homology to bacterial lysozyme inhibitors. We demonstrate that Neisseria ACP functions as an inhibitor of mammalian lysozyme but the mechanism appears to be different from other bacterial family lysozyme inhibitors. Expression of ACP enables Neisseria spp. to tolerate human lysozyme. We propose that ACP-mediated inhibition of lysozyme activity could be important for host colonization by both pathogenic and commensal Neisseria organisms and that ACP represents not only a target for developing Neisseria vaccines but also drugs to inhibit host-pathogen interactions.
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Affiliation(s)
- María Victoria Humbert
- Neisseria Research, Molecular Microbiology, Academic Unit of Clinical and Experimental Sciences, Sir Henry Wellcome Laboratories, University of Southampton Faculty of Medicine, Southampton, United Kingdom
| | - Amaka Marian Awanye
- Faculty of Biology, Medicine and Health, University of Manchester, Michael Smith Building, Oxford Road, Manchester, United Kingdom
| | - Lu-Yun Lian
- NMR Centre for Structural Biology, Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Jeremy P. Derrick
- Faculty of Biology, Medicine and Health, University of Manchester, Michael Smith Building, Oxford Road, Manchester, United Kingdom
| | - Myron Christodoulides
- Neisseria Research, Molecular Microbiology, Academic Unit of Clinical and Experimental Sciences, Sir Henry Wellcome Laboratories, University of Southampton Faculty of Medicine, Southampton, United Kingdom
- * E-mail:
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Yang XY, Li ZQ, She Z, Geng Z, Xu JH, Gao ZQ, Dong YH. Structural analysis of Pseudomonas aeruginosa H3-T6SS immunity proteins. FEBS Lett 2016; 590:2787-96. [PMID: 27397502 DOI: 10.1002/1873-3468.12291] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 05/31/2016] [Accepted: 06/27/2016] [Indexed: 01/13/2023]
Abstract
The Pseudomonas aeruginosa PldB protein is a transkingdom effector secreted by the Type VI Secretion System (T6SS). PA5088, PA5087, and PA5086 are three immunity proteins that can suppress the virulence of PldB. We report the crystal structures of PA5088 and PA5087 at 2.0 and 2.1 Å resolution, respectively. PA5088 and PA5087 both consist of several Sel1-like Repeats (SLRs) and form super-ring folds. Our structural analysis of these proteins revealed key differences among PA5088, PA5087, and their homologs. Our docking experiments have shed light on the putative interaction mechanism of their function as phospholipase D inhibitors.
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Affiliation(s)
- Xiao-Yun Yang
- School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Zong-Qiang Li
- College of Life Science and Technology, Huazhong Agriculture University, Wuhan, China
| | - Zhun She
- Multidiscipline Research Center, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China
| | - Zhi Geng
- Multidiscipline Research Center, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China
| | - Jian-Hua Xu
- Multidiscipline Research Center, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China
| | - Zeng-Qiang Gao
- Multidiscipline Research Center, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China
| | - Yu-Hui Dong
- Multidiscipline Research Center, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China
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Alcoforado Diniz J, Liu YC, Coulthurst SJ. Molecular weaponry: diverse effectors delivered by the Type VI secretion system. Cell Microbiol 2015; 17:1742-51. [PMID: 26432982 PMCID: PMC4832377 DOI: 10.1111/cmi.12532] [Citation(s) in RCA: 114] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 09/22/2015] [Accepted: 09/25/2015] [Indexed: 12/18/2022]
Abstract
The Type VI secretion system is a widespread bacterial nanomachine, used to deliver toxins directly into eukaryotic or prokaryotic target cells. These secreted toxins, or effectors, act on diverse cellular targets, and their action provides the attacking bacterial cell with a significant fitness advantage, either against rival bacteria or eukaryotic host organisms. In this review, we discuss the delivery of diverse effectors by the Type VI secretion system, the modes of action of the so-called 'anti-bacterial' and 'anti-eukaryotic' effectors, the mechanism of self-resistance against anti-bacterial effectors and the evolutionary implications of horizontal transfer of Type VI secretion system-associated toxins. Whilst it is likely that many more effectors remain to be identified, it is already clear that toxins delivered by this secretion system represent efficient weapons against both bacteria and eukaryotes.
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Affiliation(s)
- Juliana Alcoforado Diniz
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
| | - Yi-Chia Liu
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
| | - Sarah J Coulthurst
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
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Calcium binding proteins and calcium signaling in prokaryotes. Cell Calcium 2014; 57:151-65. [PMID: 25555683 DOI: 10.1016/j.ceca.2014.12.006] [Citation(s) in RCA: 136] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 12/08/2014] [Accepted: 12/09/2014] [Indexed: 11/20/2022]
Abstract
With the continued increase of genomic information and computational analyses during the recent years, the number of newly discovered calcium binding proteins (CaBPs) in prokaryotic organisms has increased dramatically. These proteins contain sequences that closely resemble a variety of eukaryotic calcium (Ca(2+)) binding motifs including the canonical and pseudo EF-hand motifs, Ca(2+)-binding β-roll, Greek key motif and a novel putative Ca(2+)-binding domain, called the Big domain. Prokaryotic CaBPs have been implicated in diverse cellular activities such as division, development, motility, homeostasis, stress response, secretion, transport, signaling and host-pathogen interactions. However, the majority of these proteins are hypothetical, and only few of them have been studied functionally. The finding of many diverse CaBPs in prokaryotic genomes opens an exciting area of research to explore and define the role of Ca(2+) in organisms other than eukaryotes. This review presents the most recent developments in the field of CaBPs and novel advancements in the role of Ca(2+) in prokaryotes.
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Lu D, Zheng Y, Liao N, Wei L, Xu B, Liu X, Liu J. The structural basis of the Tle4–Tli4 complex reveals the self-protection mechanism of H2-T6SS inPseudomonas aeruginosa. ACTA ACUST UNITED AC 2014; 70:3233-43. [DOI: 10.1107/s1399004714023967] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 10/30/2014] [Indexed: 01/02/2023]
Abstract
The type VI secretion system (T6SS) has recently been demonstrated to mediate interbacterial competition and to discriminate between self and nonself. T6SS+bacteria employ toxic effectors to inhibit rival cells and concurrently use effector cognate immunity proteins to protect their sibling cells. The effector and immunity pairs (E–I pairs) endow the bacteria with a great advantage in niche competition. Tle4–Tli4 (PA1510–PA1509) is a newly identified E–I pair that is controlled by H2-T6SS inPseudomonas aeruginosa. Tle4 exhibits phospholipase activity, which destroys the cell membrane of rival cells, and the periplasm-located Tli4 in donor cells eliminates this toxic effect of Tle4. In this paper, the structure of the Tle4–Tli4 complex is reported at 1.75 Å resolution. Tle4 consists of two domains: a conserved α/β-hydrolase domain and an unusual cap domain in which two lid regions (lid1 and lid2) display a closed conformation that buries the catalytic triad in a deep funnel. Tli4 also displays a two-domain structure, in which a large lobe and a small lobe form a crab claw-like conformation. Tli4 uses this crab claw to grasp the cap domain of Tle4, especially the lid2 region, which prevents the interfacial activation of Tle4 and thus causes enzymatic dysfunction of Tle4 in sister cells.
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A disordered region in the EvpP protein from the type VI secretion system of Edwardsiella tarda is essential for EvpC binding. PLoS One 2014; 9:e110810. [PMID: 25401506 PMCID: PMC4234509 DOI: 10.1371/journal.pone.0110810] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Accepted: 09/21/2014] [Indexed: 11/19/2022] Open
Abstract
The type VI secretion system (T6SS) of pathogenic bacteria plays important roles in both virulence and inter-bacterial competitions. The effectors of T6SS are presumed to be transported either by attaching to the tip protein or by interacting with HcpI (haemolysin corregulated protein 1). In Edwardsiella tarda PPD130/91, the T6SS secreted protein EvpP (E. tardavirulent protein P) is found to be essential for virulence and directly interacts with EvpC (Hcp-like), suggesting that it could be a potential effector. Using limited protease digestion, nuclear magnetic resonance heteronuclear Nuclear Overhauser Effects, and hydrogen-deuterium exchange mass spectrometry, we confirmed that the dimeric EvpP (40 kDa) contains a substantial proportion (40%) of disordered regions but still maintains an ordered and folded core domain. We show that an N-terminal, 10-kDa, protease-resistant fragment in EvpP connects to a shorter, 4-kDa protease-resistant fragment through a highly flexible region, which is followed by another disordered region at the C-terminus. Within this C-terminal disordered region, residues Pro143 to Ile168 are essential for its interaction with EvpC. Unlike the highly unfolded T3SS effector, which has a lower molecular weight and is maintained in an unfolded conformation with a dedicated chaperone, the T6SS effector seems to be relatively larger, folded but partially disordered and uses HcpI as a chaperone.
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Ghequire MGK, De Mot R. Ribosomally encoded antibacterial proteins and peptides from Pseudomonas. FEMS Microbiol Rev 2014; 38:523-68. [PMID: 24923764 DOI: 10.1111/1574-6976.12079] [Citation(s) in RCA: 138] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 05/05/2014] [Accepted: 05/16/2014] [Indexed: 12/26/2022] Open
Abstract
Members of the Pseudomonas genus produce diverse secondary metabolites affecting other bacteria, fungi or predating nematodes and protozoa but are also equipped with the capacity to secrete different types of ribosomally encoded toxic peptides and proteins, ranging from small microcins to large tailocins. Studies with the human pathogen Pseudomonas aeruginosa have revealed that effector proteins of type VI secretion systems are part of the antibacterial armamentarium deployed by pseudomonads. A novel class of antibacterial proteins with structural similarity to plant lectins was discovered by studying antagonism among plant-associated Pseudomonas strains. A genomic perspective on pseudomonad bacteriocinogeny shows that the modular architecture of S pyocins of P. aeruginosa is retained in a large diversified group of bacteriocins, most of which target DNA or RNA. Similar modularity is present in as yet poorly characterized Rhs (recombination hot spot) proteins and CDI (contact-dependent inhibition) proteins. Well-delimited domains for receptor recognition or cytotoxicity enable the design of chimeric toxins with novel functionalities, which has been applied successfully for S and R pyocins. Little is known regarding how these antibacterials are released and ultimately reach their targets. Other remaining issues concern the identification of environmental triggers activating these systems and assessment of their ecological impact in niches populated by pseudomonads.
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