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Das S, Das S, Rath PP, Banerjee A, Gourinath S, Mukhopadhyay AK, Maiti S. Hemolysin Coregulated Protein (HCP) from Vibrio Cholerae Interacts with the Host Cell Actin Cytoskeleton. ACS Infect Dis 2024; 10:2886-2898. [PMID: 39079033 DOI: 10.1021/acsinfecdis.4c00265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/10/2024]
Abstract
Vibrio cholerae (V. cholerae), the etiological agent of cholera, employs various virulence factors to adapt and thrive within both aquatic and human host environments. Among these factors, the type VI secretion system (T6SS) stands out as one of the crucial determinants of its pathogenicity. Valine glycine repeat protein G1 (VgrG1) and hemolysin coregulated protein (HCP) are considered major effector molecules of T6SS. Previous studies have highlighted that VgrG1 interacts with HCP proteins. Additionally, it has been shown that VgrG1 possesses an actin cross-linking domain (ACD) with actin-binding activity. Interestingly, it was reported that purified HCP protein treatment increased the stress fibers within cells. Therefore, we hypothesize that HCP may interact with host cell actin, potentially playing a role in the cytoskeletal rearrangement during V. cholerae infection. To test this hypothesis, we characterized HCP from the V. cholerae O139 serotype and demonstrated its interaction with actin monomers. In silico analysis and experimental validation revealed the presence of an actin-binding site within HCP. Furthermore, overexpression of HCP resulted in its colocalization with actin stress fibers in host cells. Our findings establish HCP as an effector molecule for potent host cell actin cytoskeleton remodeling during V. cholerae infection, providing new insights into bacterial pathogenicity mechanisms. Understanding the interplay between bacterial effectors and host cell components is crucial for developing targeted therapeutic interventions against cholera and related infectious diseases.
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Affiliation(s)
- Shubham Das
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Nadia, Mohanpur, West Bengal 741246, India
| | - Saikat Das
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Nadia, Mohanpur, West Bengal 741246, India
| | | | - Aishwarya Banerjee
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Nadia, Mohanpur, West Bengal 741246, India
| | - Samudrala Gourinath
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | | | - Sankar Maiti
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Nadia, Mohanpur, West Bengal 741246, India
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Wu P, Rao C, Liu W, Zhang Z, Nan D, Chen J, Wang M, Wen Y, Yan J, Yue J, Mao X, Li Q. Anti-Hcp1 Monoclonal Antibody Is Protective against Burkholderia pseudomallei Infection via Recognizing Amino Acids at Asp95-Leu114. Pathogens 2023; 13:43. [PMID: 38251350 PMCID: PMC10818278 DOI: 10.3390/pathogens13010043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 12/21/2023] [Accepted: 12/27/2023] [Indexed: 01/23/2024] Open
Abstract
Melioidosis, a severe tropical illness caused by Burkholderia pseudomallei, poses significant treatment challenges due to limited therapeutic options and the absence of effective vaccines. The pathogen's intrinsic resistance to numerous antibiotics and propensity to induce sepsis during acute infections further complicate management strategies. Thus, exploring alternative methods for prevention and treatment is crucial. Monoclonal antibodies (mAbs) have emerged as a promising strategy for the prevention and treatment of infectious diseases. This study focused on generating three mAbs (13F1, 14G11, and 15D9) targeting hemolysin-coregulated protein 1 (Hcp1), a protein involved in the type VI secretion system cluster 1 (T6SS1) of B. pseudomallei. Notably, pretreatment with 13F1 mAb significantly reduced the intracellular survival of B. pseudomallei and inhibited the formation of macrophage-derived multinucleated giant cells (MNGCs). This protective effect was also observed in vivo. We identified a sequence of amino acids (Asp95-Leu114) within Hcp1 as the likely binding site for 13F1 mAb. In summary, our findings reveal that 13F1 mAb counteracts infection by targeting Hcp1, offering potential new targets and insights for melioidosis prevention.
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Affiliation(s)
- Pan Wu
- Department of Clinical Microbiology and Immunology, College of Pharmacy and Laboratory Medicine, Army Medical University (Third Military Medical University), Chongqing 400000, China; (P.W.); (W.L.); (J.C.); (M.W.); (Y.W.); (J.Y.)
| | - Chenglong Rao
- Department of Clinical Microbiology and Immunology, College of Pharmacy and Laboratory Medicine, Army Medical University (Third Military Medical University), Chongqing 400000, China; (P.W.); (W.L.); (J.C.); (M.W.); (Y.W.); (J.Y.)
| | - Wenzheng Liu
- Department of Clinical Microbiology and Immunology, College of Pharmacy and Laboratory Medicine, Army Medical University (Third Military Medical University), Chongqing 400000, China; (P.W.); (W.L.); (J.C.); (M.W.); (Y.W.); (J.Y.)
| | - Ziyuan Zhang
- Department of Clinical Microbiology and Immunology, College of Pharmacy and Laboratory Medicine, Army Medical University (Third Military Medical University), Chongqing 400000, China; (P.W.); (W.L.); (J.C.); (M.W.); (Y.W.); (J.Y.)
| | - Dongqi Nan
- Department of Clinical Microbiology and Immunology, College of Pharmacy and Laboratory Medicine, Army Medical University (Third Military Medical University), Chongqing 400000, China; (P.W.); (W.L.); (J.C.); (M.W.); (Y.W.); (J.Y.)
| | - Jiangao Chen
- Department of Clinical Microbiology and Immunology, College of Pharmacy and Laboratory Medicine, Army Medical University (Third Military Medical University), Chongqing 400000, China; (P.W.); (W.L.); (J.C.); (M.W.); (Y.W.); (J.Y.)
| | - Minyang Wang
- Department of Clinical Microbiology and Immunology, College of Pharmacy and Laboratory Medicine, Army Medical University (Third Military Medical University), Chongqing 400000, China; (P.W.); (W.L.); (J.C.); (M.W.); (Y.W.); (J.Y.)
| | - Yuan Wen
- Department of Clinical Microbiology and Immunology, College of Pharmacy and Laboratory Medicine, Army Medical University (Third Military Medical University), Chongqing 400000, China; (P.W.); (W.L.); (J.C.); (M.W.); (Y.W.); (J.Y.)
| | - Jingmin Yan
- Department of Clinical Microbiology and Immunology, College of Pharmacy and Laboratory Medicine, Army Medical University (Third Military Medical University), Chongqing 400000, China; (P.W.); (W.L.); (J.C.); (M.W.); (Y.W.); (J.Y.)
| | - Juanjuan Yue
- Department of Clinical Microbiology and Immunology, College of Pharmacy and Laboratory Medicine, Army Medical University (Third Military Medical University), Chongqing 400000, China; (P.W.); (W.L.); (J.C.); (M.W.); (Y.W.); (J.Y.)
| | - Xuhu Mao
- Department of Clinical Microbiology and Immunology, College of Pharmacy and Laboratory Medicine, Army Medical University (Third Military Medical University), Chongqing 400000, China; (P.W.); (W.L.); (J.C.); (M.W.); (Y.W.); (J.Y.)
- State Key Laboratory of Trauma and Chemical Poisoning, Army Medical University (Third Military Medical University), Chongqing 400000, China
| | - Qian Li
- Department of Clinical Microbiology and Immunology, College of Pharmacy and Laboratory Medicine, Army Medical University (Third Military Medical University), Chongqing 400000, China; (P.W.); (W.L.); (J.C.); (M.W.); (Y.W.); (J.Y.)
- State Key Laboratory of Trauma and Chemical Poisoning, Army Medical University (Third Military Medical University), Chongqing 400000, China
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3
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Joiner JD, Steinchen W, Mozer N, Kronenberger T, Bange G, Poso A, Wagner S, Hartmann MD. HilE represses the activity of the Salmonella virulence regulator HilD via a mechanism distinct from that of intestinal long-chain fatty acids. J Biol Chem 2023; 299:105387. [PMID: 37890783 PMCID: PMC10696396 DOI: 10.1016/j.jbc.2023.105387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2023] [Revised: 10/11/2023] [Accepted: 10/16/2023] [Indexed: 10/29/2023] Open
Abstract
The expression of virulence factors essential for the invasion of host cells by Salmonella enterica is tightly controlled by a network of transcription regulators. The AraC/XylS transcription factor HilD is the main integration point of environmental signals into this regulatory network, with many factors affecting HilD activity. Long-chain fatty acids, which are highly abundant throughout the host intestine, directly bind to and repress HilD, acting as environmental cues to coordinate virulence gene expression. The regulatory protein HilE also negatively regulates HilD activity, through a protein-protein interaction. Both of these regulators inhibit HilD dimerization, preventing HilD from binding to target DNA. We investigated the structural basis of these mechanisms of HilD repression. Long-chain fatty acids bind to a conserved pocket in HilD, in a comparable manner to that reported for other AraC/XylS regulators, whereas HilE forms a stable heterodimer with HilD by binding to the HilD dimerization interface. Our results highlight two distinct, mutually exclusive mechanisms by which HilD activity is repressed, which could be exploited for the development of new antivirulence leads.
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Affiliation(s)
- Joe D Joiner
- Department of Protein Evolution, Max Planck Institute for Biology Tübingen, Tübingen, Germany
| | - Wieland Steinchen
- Center for Synthetic Microbiology, Philipps University of Marburg, Marburg, Germany; Department of Chemistry, Philipps University of Marburg, Marburg, Germany
| | - Nick Mozer
- Department of Protein Evolution, Max Planck Institute for Biology Tübingen, Tübingen, Germany
| | - Thales Kronenberger
- Department of Internal Medicine VIII, University Hospital Tübingen, Tübingen, Germany; Institute of Pharmacy, Pharmaceutical/Medicinal Chemistry and Tübingen Center for Academic Drug Discovery & Development (TüCAD2), Eberhard Karls University Tübingen, Tübingen, Germany; School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland; Excellence Cluster "Controlling Microbes to Fight Infections" (CMFI), Tübingen, Germany
| | - Gert Bange
- Center for Synthetic Microbiology, Philipps University of Marburg, Marburg, Germany; Department of Chemistry, Philipps University of Marburg, Marburg, Germany
| | - Antti Poso
- Department of Internal Medicine VIII, University Hospital Tübingen, Tübingen, Germany; Institute of Pharmacy, Pharmaceutical/Medicinal Chemistry and Tübingen Center for Academic Drug Discovery & Development (TüCAD2), Eberhard Karls University Tübingen, Tübingen, Germany; School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland
| | - Samuel Wagner
- Excellence Cluster "Controlling Microbes to Fight Infections" (CMFI), Tübingen, Germany; Interfaculty Institute of Microbiology and Infection Medicine (IMIT), University of Tübingen, Tübingen, Germany; Partner-site Tübingen, German Center for Infection Research (DZIF), Tübingen, Germany
| | - Marcus D Hartmann
- Department of Protein Evolution, Max Planck Institute for Biology Tübingen, Tübingen, Germany; Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany.
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He W, Wu K, Ouyang Z, Bai Y, Luo W, Wu D, An H, Guo Y, Jiao M, Qin Q, Zhang J, Wu Y, She J, Hwang PM, Zheng F, Zhu L, Wen Y. Structure and assembly of type VI secretion system cargo delivery vehicle. Cell Rep 2023; 42:112781. [PMID: 37421630 DOI: 10.1016/j.celrep.2023.112781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2022] [Revised: 05/06/2023] [Accepted: 06/25/2023] [Indexed: 07/10/2023] Open
Abstract
Type VI secretion system is widely used in Gram-negative bacteria for injecting toxic effectors into neighboring prokaryotic or eukaryotic cells. Various effectors can be loaded onto the T6SS delivery tube via its core components: Hcp, VgrG, or PAAR. Here, we report 2.8-Å resolution cryo-EM structure of intact T6SS Hcp5-VgrG-PAAR cargo delivery system and crystal structure of unbound Hcp5 from B. fragilis NCTC 9343. Loading of Hcp5 hexameric ring onto VgrG causes expansion of its inner cavity and external surface, explaining how structural changes could be propagated to regulate co-polymerization and surrounding contractile sheath. High-affinity binding between Hcp and VgrG causes entropically unfavorable structuring of long loops. Furthermore, interactions between VgrG trimer and Hcp hexamer are asymmetric, with three of the six Hcp monomers exhibiting a major loop flip. Our study provides insights into the assembly, loading, and firing of T6SS nanomachine that contributes to bacterial inter-species competition and host interactions.
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Affiliation(s)
- Wenbo He
- Center for Microbiome Research of Med-X Institute, Shaanxi Provincial Key Laboratory of Sepsis in Critical Care Medicine, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, China
| | - Ke Wu
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Zhenlin Ouyang
- Center for Microbiome Research of Med-X Institute, Shaanxi Provincial Key Laboratory of Sepsis in Critical Care Medicine, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, China
| | - Yixin Bai
- Center for Microbiome Research of Med-X Institute, Shaanxi Provincial Key Laboratory of Sepsis in Critical Care Medicine, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, China
| | - Wen Luo
- Department of Oncology, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Di Wu
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Hao An
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Yucheng Guo
- The Key Laboratory of Environment and Genes Related to Disease of Ministry of Education Health Science Center, Xi'an Jiaotong University, Xi'an 710061, China
| | - Min Jiao
- Center for Microbiome Research of Med-X Institute, Shaanxi Provincial Key Laboratory of Sepsis in Critical Care Medicine, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, China
| | - Qian Qin
- Center for Microbiome Research of Med-X Institute, Shaanxi Provincial Key Laboratory of Sepsis in Critical Care Medicine, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, China
| | - Jiaxin Zhang
- The Key Laboratory of Environment and Genes Related to Disease of Ministry of Education Health Science Center, Xi'an Jiaotong University, Xi'an 710061, China
| | - Yi Wu
- The Key Laboratory of Environment and Genes Related to Disease of Ministry of Education Health Science Center, Xi'an Jiaotong University, Xi'an 710061, China
| | - Junjun She
- Center for Microbiome Research of Med-X Institute, Shaanxi Provincial Key Laboratory of Sepsis in Critical Care Medicine, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, China
| | - Peter M Hwang
- Department of Biochemistry, Faculty of Medicine & Dentistry, Edmonton, AB T6G 2R3, Canada
| | - Fang Zheng
- The Key Laboratory of Environment and Genes Related to Disease of Ministry of Education Health Science Center, Xi'an Jiaotong University, Xi'an 710061, China
| | - Li Zhu
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China; Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Electron Microscopy Centre of Lanzhou University, Lanzhou University, Lanzhou 730000, China.
| | - Yurong Wen
- Center for Microbiome Research of Med-X Institute, Shaanxi Provincial Key Laboratory of Sepsis in Critical Care Medicine, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, China; The Key Laboratory of Environment and Genes Related to Disease of Ministry of Education Health Science Center, Xi'an Jiaotong University, Xi'an 710061, China.
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Yan J, Chen J, Mao X, Li Q. Improvements in skills and knowledge after a comprehensive ELISA teaching course for biotechnology undergraduates. BIOCHEMISTRY AND MOLECULAR BIOLOGY EDUCATION : A BIMONTHLY PUBLICATION OF THE INTERNATIONAL UNION OF BIOCHEMISTRY AND MOLECULAR BIOLOGY 2023; 51:418-427. [PMID: 37139960 DOI: 10.1002/bmb.21739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Revised: 03/24/2023] [Accepted: 04/18/2023] [Indexed: 05/05/2023]
Abstract
As a universal and extensively adopted technique, enzyme-linked immunosorbent assay (ELISA) can be used to detect and quantify small molecules in many applications both clinical and analytical. However, generally, students experiment mechanically using commercial ELISA kits according to the instructions and eventually produce a standard curve to calculate the concentration of the sample to be measured, cannot understand the critical factors and process of method establishment. This study systematically introduced undergraduates to using the pathogen-specific antigen and establishing an indirect ELISA method to detect the diagnostic target pathogen Burkholderia pseudomallei. This course aimed to develop the experimental skills of the students and improve their scientific research knowledge, which fully embody the organic combination of scientific research and teaching. Students independently selected the diagnostic antigen target of interest, obtained the antigen proteins using genetic engineering techniques, and established an ELISA method through a series of conditional optimization experiments. In addition, typical student-generated data, experimental methods, and a student feedback interpretation are presented in this study. Overall, the students were able to combine abstract knowledge with practice and understand the principles and applications of antigen-antibody interactions, thus enabling them to gain practical experience in molecular biology techniques, and learn how to use this principle to establish an ELISA method for detecting infectious diseases.
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Affiliation(s)
- Jingmin Yan
- Department of Clinical Microbiology and Immunology, College of Pharmacy and Medical Laboratory, Army Medical University (Third Military Medical University), Chongqing, China
| | - Jiangao Chen
- Department of Clinical Microbiology and Immunology, College of Pharmacy and Medical Laboratory, Army Medical University (Third Military Medical University), Chongqing, China
- Department of General Medicine, Southwest Hospital, Army Medical University (Third Military Medical University), Chongqing, China
| | - Xuhu Mao
- Department of Clinical Microbiology and Immunology, College of Pharmacy and Medical Laboratory, Army Medical University (Third Military Medical University), Chongqing, China
| | - Qian Li
- Department of Clinical Microbiology and Immunology, College of Pharmacy and Medical Laboratory, Army Medical University (Third Military Medical University), Chongqing, China
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Chi Y, Jiao H, Ran J, Xiong C, Wei J, Ozdemir E, Wu R. Construction and efficacy of Aeromonas veronii mutant Δhcp as a live attenuated vaccine for the largemouth bass (Micropterus salmoides). FISH & SHELLFISH IMMUNOLOGY 2023; 136:108694. [PMID: 36944414 DOI: 10.1016/j.fsi.2023.108694] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 03/13/2023] [Accepted: 03/15/2023] [Indexed: 06/18/2023]
Abstract
Aeromonas veronii is a human and animal co-pathogenic bacterium that could have a significant negative impact on both human health and aquaculture. In this study, a mutant strain of A. veronii with deletion of the hemolysin co-regulated protein (hcp) gene was constructed (Δhcp-AV). Compared with the wild strain, Δhcp-AV showed significantly reduced growth capacity and biofilm formation ability. Motility tests showed that the hcp gene had no significant effect on the swimming and swarming ability. In addition, the pathogenicity was also reduced. To evaluate the efficacy of Δhcp-AV as a live attenuated vaccine for prevention of Aeromonas veronii infection, we compared the immune response of largemouth bass (Micropterus salmoides) after immunization with 500 μL of 1.47 × 105 CFU/mL of Δhcp-AV and 4 × 108 CFU/mL of inactivated A. veronii. Obvious increases of serum immune related enzyme activity were observed in immunization groups. Expression levels of immune-related genes in Δhcp-AV group were up-regulated, and higher than those in inactivated A. veronii group. After challenging with live A. veronii, the relative percent survival (RPS) was 100% in Δhcp- AV group, whereas the RPS was 76.67% in inactivated A. veronii group. Our data suggest that the live attenuated vaccine Δhcp- AV could elicit a stronger immune response and provide a higher RPS than inactivated A. veronii. These data suggest that hcp gene is an important virulence factor of A. veronii, and the live attenuated vaccine Δhcp-AV is safe and effective for prevention A. veronii infection in M. salmoides farming.
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Affiliation(s)
- Yuyu Chi
- College of Fisheries, Southwest University, Chongqing, 400715, China; Key Laboratory of Freshwater Fish Reproduction and Development, Minister of Education, Southwest University, Chongqing, 400715, China.
| | - Hanyang Jiao
- College of Fisheries, Southwest University, Chongqing, 400715, China; Key Laboratory of Freshwater Fish Reproduction and Development, Minister of Education, Southwest University, Chongqing, 400715, China.
| | - Jiayan Ran
- College of Fisheries, Southwest University, Chongqing, 400715, China; Key Laboratory of Freshwater Fish Reproduction and Development, Minister of Education, Southwest University, Chongqing, 400715, China.
| | - Chuanyu Xiong
- College of Fisheries, Southwest University, Chongqing, 400715, China; Key Laboratory of Freshwater Fish Reproduction and Development, Minister of Education, Southwest University, Chongqing, 400715, China.
| | - Jinming Wei
- College of Fisheries, Southwest University, Chongqing, 400715, China; Key Laboratory of Freshwater Fish Reproduction and Development, Minister of Education, Southwest University, Chongqing, 400715, China.
| | - Eda Ozdemir
- Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, 39762, USA.
| | - Ronghua Wu
- College of Fisheries, Southwest University, Chongqing, 400715, China; Key Laboratory of Freshwater Fish Reproduction and Development, Minister of Education, Southwest University, Chongqing, 400715, China.
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Agnello E, Pajak J, Liu X, Kelch BA. Conformational dynamics control assembly of an extremely long bacteriophage tail tube. J Biol Chem 2023; 299:103021. [PMID: 36791911 PMCID: PMC10034513 DOI: 10.1016/j.jbc.2023.103021] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2022] [Revised: 02/06/2023] [Accepted: 02/07/2023] [Indexed: 02/15/2023] Open
Abstract
Tail tube assembly is an essential step in the lifecycle of long-tailed bacteriophages. Limited structural and biophysical information has impeded an understanding of assembly and stability of their long, flexible tail tubes. The hyperthermophilic phage P74-26 is particularly intriguing as it has the longest tail of any known virus (nearly 1 μm) and is the most thermostable known phage. Here, we use structures of the P74-26 tail tube along with an in vitro system for studying tube assembly kinetics to propose the first molecular model for the tail tube assembly of long-tailed phages. Our high-resolution cryo-EM structure provides insight into how the P74-26 phage assembles through flexible loops that fit into neighboring rings through tight "ball-and-socket"-like interactions. Guided by this structure, and in combination with mutational, light scattering, and molecular dynamics simulations data, we propose a model for the assembly of conserved tube-like structures across phage and other entities possessing tail tube-like proteins. We propose that formation of a full ring promotes the adoption of a tube elongation-competent conformation among the flexible loops and their corresponding sockets, which is further stabilized by an adjacent ring. Tail assembly is controlled by the cooperative interaction of dynamic intraring and interring contacts. Given the structural conservation among tail tube proteins and tail-like structures, our model can explain the mechanism of high-fidelity assembly of long, stable tubes.
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Affiliation(s)
- Emily Agnello
- Department of Biochemistry and Molecular Biotechnology, University of Massachusetts Chan Medical School, Worcester Massachusetts, USA
| | - Joshua Pajak
- Department of Biochemistry and Molecular Biotechnology, University of Massachusetts Chan Medical School, Worcester Massachusetts, USA
| | - Xingchen Liu
- Department of Biochemistry and Molecular Biotechnology, University of Massachusetts Chan Medical School, Worcester Massachusetts, USA
| | - Brian A Kelch
- Department of Biochemistry and Molecular Biotechnology, University of Massachusetts Chan Medical School, Worcester Massachusetts, USA.
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Gabbert AD, Mydosh JL, Talukdar PK, Gloss LM, McDermott JE, Cooper KK, Clair GC, Konkel ME. The Missing Pieces: The Role of Secretion Systems in Campylobacter jejuni Virulence. Biomolecules 2023; 13:135. [PMID: 36671522 PMCID: PMC9856085 DOI: 10.3390/biom13010135] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 12/29/2022] [Accepted: 01/05/2023] [Indexed: 01/10/2023] Open
Abstract
Campylobacter jejuni is likely the most common bacterial cause of gastroenteritis worldwide, responsible for millions of cases of inflammatory diarrhea characterized by severe abdominal cramps and blood in the stool. Further, C. jejuni infections are associated with post-infection sequelae in developed countries and malnutrition and growth-stunting in low- and middle-income countries. Despite the increasing prevalence of the disease, campylobacteriosis, and the recognition that this pathogen is a serious health threat, our understanding of C. jejuni pathogenesis remains incomplete. In this review, we focus on the Campylobacter secretion systems proposed to contribute to host-cell interactions and survival in the host. Moreover, we have applied a genomics approach to defining the structural and mechanistic features of C. jejuni type III, IV, and VI secretion systems. Special attention is focused on the flagellar type III secretion system and the prediction of putative effectors, given that the proteins exported via this system are essential for host cell invasion and the inflammatory response. We conclude that C. jejuni does not possess a type IV secretion system and relies on the type III and type VI secretion systems to establish a niche and potentiate disease.
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Affiliation(s)
- Amber D. Gabbert
- School of Molecular Biosciences, College of Veterinary Sciences, Washington State University, Pullman, WA 99164, USA
| | - Jennifer L. Mydosh
- School of Animal and Comparative Biomedical Sciences, The University of Arizona, Tucson, AZ 85721, USA
| | - Prabhat K. Talukdar
- School of Molecular Biosciences, College of Veterinary Sciences, Washington State University, Pullman, WA 99164, USA
| | - Lisa M. Gloss
- School of Molecular Biosciences, College of Veterinary Sciences, Washington State University, Pullman, WA 99164, USA
| | - Jason E. McDermott
- Integrative Omics, Pacific Northwest National Laboratory, Richland, WA 99354, USA
| | - Kerry K. Cooper
- School of Animal and Comparative Biomedical Sciences, The University of Arizona, Tucson, AZ 85721, USA
| | - Geremy C. Clair
- Integrative Omics, Pacific Northwest National Laboratory, Richland, WA 99354, USA
| | - Michael E. Konkel
- School of Molecular Biosciences, College of Veterinary Sciences, Washington State University, Pullman, WA 99164, USA
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Zhu K, Li G, Li J, Zheng M, Peng X, Rao Y, Li M, Zhou R, Rao X. Hcp1-loaded staphylococcal membrane vesicle vaccine protects against acute melioidosis. Front Immunol 2022; 13:1089225. [PMID: 36618368 PMCID: PMC9822774 DOI: 10.3389/fimmu.2022.1089225] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 12/13/2022] [Indexed: 12/24/2022] Open
Abstract
Burkholderia pseudomallei is the causal agent of melioidosis, a deadly tropical infectious disease that lacks a vaccine. On the basis of the attenuated Staphylococcus aureus RN4220-Δagr (RN), we engineered the RN4220-Δagr/pdhB-hcp1 strain (RN-Hcp1) to generate B. pseudomallei hemolysin-coregulated protein 1 (Hcp1)-loaded membrane vesicles (hcp1MVs). The immunization of BALB/c mice with hcp1MVs mixed with adjuvant by a three-dose regimen increased the serum specific IgG production. The serum levels of inflammatory factors, including TNF-α and IL-6, in hcp1MV-vaccinated mice were comparable with those in PBS-challenged mice. The partial adjuvant effect of staphylococcal MVs was observed with the elevation of specific antibody titer in hcp1MV-vaccinated mice relative to those that received the recombinant Hcp1 protein (rHcp1) or MVs derived from RN strain (ΔagrMVs). The hcp1MVs/adjuvant vaccine protected 70% of mice from lethal B. pseudomallei challenge. Immunization with hcp1MVs only protected 60% of mice, whereas vaccination with rHcp1 or ΔagrMVs conferred no protection. Moreover, mice that received hcp1MVs/adjuvant and hcp1MVs immunization had low serum TNF-α and IL-6 levels and no inflammatory infiltration in comparison with other groups. In addition, all surviving mice in hcp1MVs/adjuvant and hcp1MVs groups exhibited no culturable bacteria in their lungs, livers, and spleens five days postinfection. Overall, our data highlighted a new strategy for developing B. pseudomallei vaccine and showed that Hcp1-incorporated staphylococcal MV is a promising candidate for the prevention of acute melioidosis.
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Affiliation(s)
- Keting Zhu
- Department of Emergency Medicine, Xinqiao Hospital, Army Medical University, Chongqing, China
| | - Gang Li
- Department of Microbiology, College of Basic Medical Sciences, Army Medical University, Chongqing, China
| | - Jia Li
- Department of Emergency Medicine, Xinqiao Hospital, Army Medical University, Chongqing, China
| | - Mingxia Zheng
- Department of Emergency Medicine, Xinqiao Hospital, Army Medical University, Chongqing, China
| | - Xiaohui Peng
- Department of Emergency Medicine, Xinqiao Hospital, Army Medical University, Chongqing, China
| | - Yifan Rao
- Department of Emergency Medicine, Xinqiao Hospital, Army Medical University, Chongqing, China
| | - Ming Li
- Department of Microbiology, College of Basic Medical Sciences, Army Medical University, Chongqing, China,*Correspondence: Ming Li, ; Renjie Zhou, ; Xiancai Rao,
| | - Renjie Zhou
- Department of Emergency Medicine, Xinqiao Hospital, Army Medical University, Chongqing, China,*Correspondence: Ming Li, ; Renjie Zhou, ; Xiancai Rao,
| | - Xiancai Rao
- Department of Microbiology, College of Basic Medical Sciences, Army Medical University, Chongqing, China,*Correspondence: Ming Li, ; Renjie Zhou, ; Xiancai Rao,
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10
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Abstract
The soil saprophyte, Burkholderia pseudomallei, is the causative agent of melioidosis, a disease endemic in South East Asia and northern Australia. Exposure to B. pseudomallei by either inhalation or inoculation can lead to severe disease. B. pseudomallei rapidly shifts from an environmental organism to an aggressive intracellular pathogen capable of rapidly spreading around the body. The expression of multiple virulence factors at every stage of intracellular infection allows for rapid progression of infection. Following invasion or phagocytosis, B. pseudomallei resists host-cell killing mechanisms in the phagosome, followed by escape using the type III secretion system. Several secreted virulence factors manipulate the host cell, while bacterial cells undergo a shift in energy metabolism allowing for overwhelming intracellular replication. Polymerisation of host cell actin into “actin tails” propels B. pseudomallei to the membranes of host cells where the type VI secretion system fuses host cells into multinucleated giant cells (MNGCs) to facilitate cell-to-cell dissemination. This review describes the various mechanisms used by B. pseudomallei to survive within cells.
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Affiliation(s)
- Nicole M Bzdyl
- The Marshall Centre for Infectious Diseases Research and Training, School of Biomedical Sciences, University of Western Australia, Perth, Western Australia, 6009, Australia
| | - Clare L Moran
- The Marshall Centre for Infectious Diseases Research and Training, School of Biomedical Sciences, University of Western Australia, Perth, Western Australia, 6009, Australia
| | - Justine Bendo
- The Marshall Centre for Infectious Diseases Research and Training, School of Biomedical Sciences, University of Western Australia, Perth, Western Australia, 6009, Australia
| | - Mitali Sarkar-Tyson
- The Marshall Centre for Infectious Diseases Research and Training, School of Biomedical Sciences, University of Western Australia, Perth, Western Australia, 6009, Australia
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11
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Functional Activities of O-Polysaccharide and Hemolysin Coregulated Protein 1 Specific Antibodies Isolated from Melioidosis Patients. Infect Immun 2022; 90:e0021422. [PMID: 36226942 PMCID: PMC9670879 DOI: 10.1128/iai.00214-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Melioidosis is a fatal tropical disease caused by the environmental Gram-negative bacterium, Burkholderia pseudomallei. This bacterium is intrinsically resistant to several antibiotics and treatment of melioidosis requires prolonged antibiotic administration. To date, there are no vaccines available for melioidosis. Previous studies have shown that humoral immunity is critical for surviving melioidosis and that O-polysaccharide (OPS) and hemolysin coregulated protein 1 (Hcp1) are important protective antigens in animal models of melioidosis. Our previous studies revealed that melioidosis patients had high levels of OPS- and Hcp1-specific antibodies and that IgG against OPS (IgG-OPS) and Hcp1 (IgG-Hcp1) were associated with patient survival. In this study, we characterized the potential function(s) of IgG-OPS and IgG-Hcp1 from melioidosis patients. IgG-OPS and IgG-Hcp1 were purified from pooled serum obtained from melioidosis patients using immuno-affinity chromatography. Antibody-dependent cellular phagocytosis assays were performed with pooled serum from melioidosis patients and compared with serum obtained from healthy controls. Serum from melioidosis patients significantly enhanced B. pseudomallei uptake into the human monocytic cell line THP-1 compared with pooled serum from healthy donors. Enhanced opsonization was observed with IgG-OPS and IgG-Hcp1 in a dose-dependent manner. Antibody-dependent complement deposition assays were performed with IgG-OPS and IgG-Hcp1 using flow cytometry and showed that there was enhanced C3b deposition on the surface of B. pseudomallei treated with IgG-OPS but to a lesser degree with IgG-Hcp1. This study provides insight into the function of IgG-OPS and IgG-Hcp1 in human melioidosis and supports that OPS and Hcp1 are potential vaccine antigens for immunization against melioidosis.
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12
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Song L, Wu J, Weng K, Yao F, Vongsangnak W, Zhu G, Chen G, Zhang Y, Xu Q. The salmonella effector Hcp modulates infection response, and affects salmonella adhesion and egg contamination incidences in ducks. Front Cell Infect Microbiol 2022; 12:948237. [PMID: 36262184 PMCID: PMC9575552 DOI: 10.3389/fcimb.2022.948237] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 07/05/2022] [Indexed: 11/17/2022] Open
Abstract
Salmonella Entertidis (SE) often causes persistent infections and egg contamination in laying ducks. Hcp, the core structural and effector proteins of the Type VI Secretion System (T6SS) in SE, contributes to bacterial invasion, adhesion and virulence. However, little is known about the effect of Hcp on the host’s infection responses and egg contamination incidences in duck. Herein, we generated an hcp deletion mutant SE MY1△hcp and detected its ability to invade duck granulosa cells (dGCs) and contaminate eggs. In comparison with MY1-infected group, the SE adhesion decreased by 15.96% in MY1△hcp-infected dGCs, and the apoptosis in MY1△hcp-infected dGCs decreased by 26.58% and 30.99% at 3 and 6 hours postinfection, respectively. However, the expression levels of immunogenic genes TLR4, NOD1, TNFα, IL-1β and proinflammatory cytokines IL-6, IL-1β, TNF-α release were markedly lower in the dGCs inoculated with MY1△hcp than that of the wild type. Besides, the laying ducks were challenged with MY1 or MY1△hcp in vivo, respectively. The lower egg production and higher egg contamination were observed in MY1-infected ducks in comparison with MY1△hcp-infected birds. Furthermore, the host’s infection response of differentially abundant proteins (DAPs) to Salmonella effector Hcp was identified using quantitative proteomics. A total of 164 DAPs were identified between the MY1- and MY1△hcp-infected cells, which were mainly engaged in the immune, hormone synthesis, cell proliferation and cell apoptotic process. Among them, STAT3, AKT1, MAPK9, MAPK14, and CREBBP were the center of the regulatory network, which might serve as key host response regulators to bacterial Hcp. In conclusion, we demonstrated that effector Hcp contributed to not only SE invasion, induction of dGCs apoptosis, and trigger of immune responses, but also enhanced contamination incidences. Also, the STAT3, AKT1, MAPK9, MAPK14, and CREBBP were identified as host’s infection response regulators of bacterial Hcp in duck. Overall, these results not only offered a novel evidence of SE ovarian transmission but also identified some promising candidate regulators during SE infection.
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Affiliation(s)
- Lina Song
- Joint International Research Laboratory of Agriculture & Agri-Product Safety of Ministry of Education, Yangzhou University, Yangzhou, China
- College of Animal Science and Technology, Yangzhou University, Yangzhou, China
| | - Jia Wu
- Joint International Research Laboratory of Agriculture & Agri-Product Safety of Ministry of Education, Yangzhou University, Yangzhou, China
- College of Animal Science and Technology, Yangzhou University, Yangzhou, China
| | - Kaiqi Weng
- Joint International Research Laboratory of Agriculture & Agri-Product Safety of Ministry of Education, Yangzhou University, Yangzhou, China
- College of Animal Science and Technology, Yangzhou University, Yangzhou, China
| | - Fenghua Yao
- Joint International Research Laboratory of Agriculture & Agri-Product Safety of Ministry of Education, Yangzhou University, Yangzhou, China
| | - Wanwipa Vongsangnak
- Department of Zoology, Faculty of Science, Kasetsart University, Bangkok, Thailand
| | - Guoqiang Zhu
- Joint International Research Laboratory of Agriculture & Agri-Product Safety of Ministry of Education, Yangzhou University, Yangzhou, China
| | - Guohong Chen
- Joint International Research Laboratory of Agriculture & Agri-Product Safety of Ministry of Education, Yangzhou University, Yangzhou, China
- College of Animal Science and Technology, Yangzhou University, Yangzhou, China
| | - Yu Zhang
- Joint International Research Laboratory of Agriculture & Agri-Product Safety of Ministry of Education, Yangzhou University, Yangzhou, China
- College of Animal Science and Technology, Yangzhou University, Yangzhou, China
- *Correspondence: Yu Zhang,
| | - Qi Xu
- Joint International Research Laboratory of Agriculture & Agri-Product Safety of Ministry of Education, Yangzhou University, Yangzhou, China
- College of Animal Science and Technology, Yangzhou University, Yangzhou, China
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13
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Klimko CP, Shoe JL, Rill NO, Hunter M, Dankmeyer JL, Talyansky Y, Schmidt LK, Orne CE, Fetterer DP, Biryukov SS, Burtnick MN, Brett PJ, DeShazer D, Cote CK. Layered and integrated medical countermeasures against Burkholderia pseudomallei infections in C57BL/6 mice. Front Microbiol 2022; 13:965572. [PMID: 36060756 PMCID: PMC9432870 DOI: 10.3389/fmicb.2022.965572] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 07/18/2022] [Indexed: 11/13/2022] Open
Abstract
Burkholderia pseudomallei, the gram-negative bacterium that causes melioidosis, is notoriously difficult to treat with antibiotics. A significant effort has focused on identifying protective vaccine strategies to prevent melioidosis. However, when used as individual medical countermeasures both antibiotic treatments (therapeutics or post-exposure prophylaxes) and experimental vaccine strategies remain partially protective. Here we demonstrate that when used in combination, current vaccine strategies (recombinant protein subunits AhpC and/or Hcp1 plus capsular polysaccharide conjugated to CRM197 or the live attenuated vaccine strain B. pseudomallei 668 ΔilvI) and co-trimoxazole regimens can result in near uniform protection in a mouse model of melioidosis due to apparent synergy associated with distinct medical countermeasures. Our results demonstrated significant improvement when examining several suboptimal antibiotic regimens (e.g., 7-day antibiotic course started early after infection or 21-day antibiotic course with delayed initiation). Importantly, this combinatorial strategy worked similarly when either protein subunit or live attenuated vaccines were evaluated. Layered and integrated medical countermeasures will provide novel treatment options for melioidosis as well as diseases caused by other pathogens that are refractory to individual strategies, particularly in the case of engineered, emerging, or re-emerging bacterial biothreat agents.
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Affiliation(s)
- Christopher P. Klimko
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, United States
| | - Jennifer L. Shoe
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, United States
| | - Nathaniel O. Rill
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, United States
| | - Melissa Hunter
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, United States
| | - Jennifer L. Dankmeyer
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, United States
| | - Yuli Talyansky
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, United States
| | - Lindsey K. Schmidt
- Department of Microbiology and Immunology, University of Nevada, Reno School of Medicine, Reno, NV, United States
| | - Caitlyn E. Orne
- Department of Microbiology and Immunology, University of Nevada, Reno School of Medicine, Reno, NV, United States
| | - David P. Fetterer
- Biostatistics Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, United States
| | - Sergei S. Biryukov
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, United States
| | - Mary N. Burtnick
- Department of Microbiology and Immunology, University of Nevada, Reno School of Medicine, Reno, NV, United States
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Paul J. Brett
- Department of Microbiology and Immunology, University of Nevada, Reno School of Medicine, Reno, NV, United States
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - David DeShazer
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, United States
| | - Christopher K. Cote
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, United States
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14
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Biryukov SS, Cote CK, Klimko CP, Dankmeyer JL, Rill NO, Shoe JL, Hunter M, Shamsuddin Z, Velez I, Hedrick ZM, Rosario-Acevedo R, Talyansky Y, Schmidt LK, Orne CE, Fetterer DP, Burtnick MN, Brett PJ, Welkos SL, DeShazer D. Evaluation of two different vaccine platforms for immunization against melioidosis and glanders. Front Microbiol 2022; 13:965518. [PMID: 36060742 PMCID: PMC9428723 DOI: 10.3389/fmicb.2022.965518] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 07/22/2022] [Indexed: 11/13/2022] Open
Abstract
Burkholderia pseudomallei and the closely related species, Burkholderia mallei, produce similar multifaceted diseases which range from rapidly fatal to protracted and chronic, and are a major cause of mortality in endemic regions. Besides causing natural infections, both microbes are Tier 1 potential biothreat agents. Antibiotic treatment is prolonged with variable results, hence effective vaccines are urgently needed. The purpose of our studies was to compare candidate vaccines that target both melioidosis and glanders to identify the most efficacious one(s) and define residual requirements for their transition to the non-human primate aerosol model. Studies were conducted in the C57BL/6 mouse model to evaluate the humoral and cell-mediated immune response and protective efficacy of three Burkholderia vaccine candidates against lethal aerosol challenges with B. pseudomallei K96243, B. pseudomallei MSHR5855, and B. mallei FMH. The recombinant vaccines generated significant immune responses to the vaccine antigens, and the live attenuated vaccine generated a greater immune response to OPS and the whole bacterial cells. Regardless of the candidate vaccine evaluated, the protection of mice was associated with a dampened cytokine response within the lungs after exposure to aerosolized bacteria. Despite being delivered by two different platforms and generating distinct immune responses, two experimental vaccines, a capsule conjugate + Hcp1 subunit vaccine and the live B. pseudomallei 668 ΔilvI strain, provided significant protection and were down-selected for further investigation and advanced development.
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Affiliation(s)
- Sergei S. Biryukov
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, United States
| | - Christopher K. Cote
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, United States
- *Correspondence: Christopher K. Cote
| | - Christopher P. Klimko
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, United States
| | - Jennifer L. Dankmeyer
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, United States
| | - Nathaniel O. Rill
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, United States
| | - Jennifer L. Shoe
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, United States
| | - Melissa Hunter
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, United States
| | - Zain Shamsuddin
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, United States
| | - Ivan Velez
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, United States
| | - Zander M. Hedrick
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, United States
| | - Raysa Rosario-Acevedo
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, United States
| | - Yuli Talyansky
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, United States
| | - Lindsey K. Schmidt
- Department of Microbiology and Immunology, University of Nevada, Reno School of Medicine, Reno, NV, United States
| | - Caitlyn E. Orne
- Department of Microbiology and Immunology, University of Nevada, Reno School of Medicine, Reno, NV, United States
| | - David P. Fetterer
- Biostatistics Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, United States
| | - Mary N. Burtnick
- Department of Microbiology and Immunology, University of Nevada, Reno School of Medicine, Reno, NV, United States
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Paul J. Brett
- Department of Microbiology and Immunology, University of Nevada, Reno School of Medicine, Reno, NV, United States
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Susan L. Welkos
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, United States
| | - David DeShazer
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Frederick, MD, United States
- David DeShazer
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15
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Major tail proteins of bacteriophages of the order Caudovirales. J Biol Chem 2021; 298:101472. [PMID: 34890646 PMCID: PMC8718954 DOI: 10.1016/j.jbc.2021.101472] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 11/15/2021] [Accepted: 11/16/2021] [Indexed: 12/18/2022] Open
Abstract
Technological advances in cryo-EM in recent years have given rise to detailed atomic structures of bacteriophage tail tubes-a class of filamentous protein assemblies that could previously only be studied on the atomic scale in either their monomeric form or when packed within a crystal lattice. These hollow elongated protein structures, present in most bacteriophages of the order Caudovirales, connect the DNA-containing capsid with a receptor function at the distal end of the tail and consist of helical and polymerized major tail proteins. However, the resolution of cryo-EM data for these systems differs enormously between different tail tube types, partly inhibiting the building of high-fidelity models and barring a combination with further structural biology methods. Here, we review the structural biology efforts within this field and highlight the role of integrative structural biology approaches that have proved successful for some of these systems. Finally, we summarize the structural elements of major tail proteins and conceptualize how different amounts of tail tube flexibility confer heterogeneity within cryo-EM maps and, thus, limit high-resolution reconstructions.
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16
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Burkholderia pseudomallei as an Enteric Pathogen: Identification of Virulence Factors Mediating Gastrointestinal Infection. Infect Immun 2020; 89:IAI.00654-20. [PMID: 33106293 DOI: 10.1128/iai.00654-20] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 10/15/2020] [Indexed: 12/24/2022] Open
Abstract
Burkholderia pseudomallei is a Gram-negative bacterium and the causative agent of melioidosis. Despite advances in our understanding of the disease, B. pseudomallei poses a significant health risk, especially in regions of endemicity, where treatment requires prolonged antibiotic therapy. Even though the respiratory and percutaneous routes are well documented and considered the main ways to acquire the pathogen, the gastrointestinal tract is believed to be an underreported and underrecognized route of infection. In the present study, we describe the development of in vitro and in vivo models to study B. pseudomallei gastrointestinal infection. Further, we report that the type 6 secretion system (T6SS) and type 1 fimbriae are important virulence factors required for gastrointestinal infection. Using a human intestinal epithelial cell line and mouse primary intestinal epithelial cells (IECs), we demonstrated that B. pseudomallei adheres, invades, and forms multinucleated giant cells, ultimately leading to cell toxicity. We demonstrated that mannose-sensitive type 1 fimbria is involved in the initial adherence of B. pseudomallei to IECs, although the impact on full virulence was limited. Finally, we also showed that B. pseudomallei requires a functional T6SS for full virulence, bacterial dissemination, and lethality in mice infected by the intragastric route. Overall, we showed that B. pseudomallei is an enteric pathogen and that type 1 fimbria is important for B. pseudomallei intestinal adherence, and we identify a new role for T6SS as a key virulence factor in gastrointestinal infection. These studies highlight the importance of gastrointestinal melioidosis as an understudied route of infection and open a new avenue for the pathogenesis of B. pseudomallei.
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17
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Wang G, Zarodkiewicz P, Valvano MA. Current Advances in Burkholderia Vaccines Development. Cells 2020; 9:E2671. [PMID: 33322641 PMCID: PMC7762980 DOI: 10.3390/cells9122671] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 12/01/2020] [Accepted: 12/09/2020] [Indexed: 12/18/2022] Open
Abstract
The genus Burkholderia includes a wide range of Gram-negative bacterial species some of which are pathogenic to humans and other vertebrates. The most pathogenic species are Burkholderia mallei, Burkholderia pseudomallei, and the members of the Burkholderia cepacia complex (Bcc). B. mallei and B. pseudomallei, the cause of glanders and melioidosis, respectively, are considered potential bioweapons. The Bcc comprises a subset of Burkholderia species associated with respiratory infections in people with chronic granulomatous disease and cystic fibrosis. Antimicrobial treatment of Burkholderia infections is difficult due to the intrinsic multidrug antibiotic resistance of these bacteria; prophylactic vaccines provide an attractive alternative to counteract these infections. Although commercial vaccines against Burkholderia infections are still unavailable, substantial progress has been made over recent years in the development of vaccines against B. pseudomallei and B. mallei. This review critically discusses the current advances in vaccine development against B. mallei, B. pseudomallei, and the Bcc.
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Affiliation(s)
| | | | - Miguel A. Valvano
- Wellcome-Wolfson Institute for Experimental Medicine, Queen’s University Belfast, Belfast BT9 7BL, UK; (G.W.); (P.Z.)
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18
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Saiprom N, Sangsri T, Tandhavanant S, Sengyee S, Phunpang R, Preechanukul A, Surin U, Tuanyok A, Lertmemongkolchai G, Chantratita W, West TE, Chantratita N. Genomic loss in environmental and isogenic morphotype isolates of Burkholderia pseudomallei is associated with intracellular survival and plaque-forming efficiency. PLoS Negl Trop Dis 2020; 14:e0008590. [PMID: 32991584 PMCID: PMC7546507 DOI: 10.1371/journal.pntd.0008590] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 10/09/2020] [Accepted: 07/13/2020] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Burkholderia pseudomallei is an environmental bacterium that causes melioidosis. A facultative intracellular pathogen, B. pseudomallei can induce multinucleated giant cells (MNGCs) leading to plaque formation in vitro. B. pseudomallei can switch colony morphotypes under stress conditions. In addition, different isolates have been reported to have varying virulence in vivo, but genomic evolution and the relationship with plaque formation is poorly understood. METHODOLOGY/PRINCIPLE FINDINGS To gain insights into genetic underpinnings of virulence of B. pseudomallei, we screened plaque formation of 52 clinical isolates and 11 environmental isolates as well as 4 isogenic morphotype isolates of B. pseudomallei strains K96243 (types II and III) and 153 (types II and III) from Thailand in A549 and HeLa cells. All isolates except one environmental strain (A4) and K96243 morphotype II were able to induce plaque formation in both cell lines. Intracellular growth assay and confocal microscopy analyses demonstrated that the two plaque-forming-defective isolates were also impaired in intracellular replication, actin polymerization and MNGC formation in infected cells. Whole genome sequencing analysis and PCR revealed that both isolates had a large genomic loss on the same region in chromosome 2, which included Bim cluster, T3SS-3 and T6SS-5 genes. CONCLUSIONS/SIGNIFICANCE Our plaque screening and genomic studies revealed evidence of impairment in plaque formation in environmental isolates of B. pseudomallei that is associated with large genomic loss of genes important for intracellular multiplication and MNGC formation. These findings suggest that the genomic and phenotypic differences of environmental isolates may be associated with clinical infection.
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Affiliation(s)
- Natnaree Saiprom
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Tanes Sangsri
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Department of Microbiology, Princess of Naradhiwas University, Narathiwat, Thailand
| | - Sarunporn Tandhavanant
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Sineenart Sengyee
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Rungnapa Phunpang
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Anucha Preechanukul
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Uriwan Surin
- Department of Medical Laboratory, Nakhon Phanom Hospital, Nakhon Phanom, Thailand
| | - Apichai Tuanyok
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, Gainesville, FL, United States of America
| | - Ganjana Lertmemongkolchai
- Centre for Research and Development of Medical Diagnostic Laboratories, Department of Clinical Immunology, Faculty of Associated Medical Science, Khon Kaen University, Khon Kaen, Thailand
| | - Wasun Chantratita
- Center for Medical Genomics, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - T. Eoin West
- Division of Pulmonary, Critical Care & Sleep Medicine, Harborview Medical Center, University of Washington, Seattle, WA, United States of America
| | - Narisara Chantratita
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
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19
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Zheng L, Wang S, Ling M, Lv Z, Lin S. Salmonella enteritidis Hcp distribute in the cytoplasm and regulate TNF signaling pathway in BHK-21 cells. 3 Biotech 2020; 10:301. [PMID: 32550118 PMCID: PMC7292845 DOI: 10.1007/s13205-020-02296-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 06/09/2020] [Indexed: 02/06/2023] Open
Abstract
Hemolysin-coregulated protein (Hcp) of Salmonella enteritidis is known to be a structural and effector protein of the T6SS, but little is known about the role of Hcp in host cells. In this study, Hcp was expressed by plasmid pEGFP-N1-hcp in BHK-21 cells and the results showed that the subcellular localization of Hcp was predominantly in the cytoplasm of BHK-21 cells. When Hcp was over-expressed by transfecting plasmid pCI-neo-hcp in BHK-21 cells and mRNA sequencing was performed to analyze differentially expressed genes, the results showed a change in the expression levels of 307 mRNAs (fold change > 2, and p < 0.01). Amongst these, 125 mRNAs were up-regulated and 182 mRNAs were down-regulated. Kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis showed that differentially expressed genes were enriched in tumor necrosis factor (TNF) signaling pathway, IL-17 signaling pathway, and cytokine-cytokine receptor interaction. Subsequently, we selected differentially expressed genes of TNF signaling pathway and verified the changes by real-time PCR. The results were consistent with the trend observed for the sequencing results. In conclusion, we demonstrated that Hcp of Salmonella enteritidis caused the change of mRNAs expression of TNF signaling pathway in the cytoplasm of BHK-21 cells.
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Affiliation(s)
- Liming Zheng
- Anhui Medical University, Hefei, 230032 People’s Republic of China
| | - Shenghua Wang
- Anhui Medical University, Hefei, 230032 People’s Republic of China
| | - Mengyu Ling
- Anhui Medical University, Hefei, 230032 People’s Republic of China
| | - Zhengmei Lv
- Anhui Medical University, Hefei, 230032 People’s Republic of China
| | - Shuai Lin
- Anhui Medical University, Hefei, 230032 People’s Republic of China
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20
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Pumpuang A, Phunpang R, Ekchariyawat P, Dulsuk A, Loupha S, Kwawong K, Charoensawat Y, Thiansukhon E, Day NPJ, Burtnick MN, Brett PJ, West TE, Chantratita N. Distinct classes and subclasses of antibodies to hemolysin co-regulated protein 1 and O-polysaccharide and correlation with clinical characteristics of melioidosis patients. Sci Rep 2019; 9:13972. [PMID: 31562344 PMCID: PMC6764960 DOI: 10.1038/s41598-019-48828-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 08/01/2019] [Indexed: 12/28/2022] Open
Abstract
Melioidosis is a tropical infectious disease caused by Burkholderia pseudomallei that results in high mortality. Hemolysin co-regulated protein 1 (Hcp1) and O-polysaccharide (OPS) are vaccine candidates and potential diagnostic antigens. The correlation of classes/subclasses of antibodies against these antigens with clinical characteristics of melioidosis patients is unknown. Antibodies in plasma samples from melioidosis patients and healthy donors were quantified by ELISA and compared with clinical features. In melioidosis patients, Hcp1 induced high IgG levels. OPS induced high IgG and IgA levels. The area under receiver operating characteristic curve (AUROCC) to discriminate melioidosis cases from healthy donors was highest for anti-Hcp1 IgG (0.92) compared to anti-Hcp1 IgA or IgM. In contrast, AUROCC for anti-OPS for IgG (0.91) and IgA (0.92) were comparable. Anti-Hcp1 IgG1 and anti-OPS IgG2 had the greatest AUROCCs (0.87 and 0.95, respectively) compared to other IgG subclasses for each antigen. Survivors had significantly higher anti-Hcp1 IgG3 levels than non-survivors. Male melioidosis patients with diabetes had higher anti-OPS IgA levels than males without diabetes. Thus, diverse and specific antibody responses are associated with distinct clinical characteristics in melioidosis, confirming the diagnostic utility of these responses and providing new insights into immune mechanisms.
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Affiliation(s)
- Apinya Pumpuang
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Department of Clinical Pathology, Faculty of Medicine, Vajira Hospital, Navamindradhiraj University, Bangkok, Thailand
| | - Rungnapa Phunpang
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Peeraya Ekchariyawat
- Department of Microbiology, Faculty of Public health, Mahidol University, Bangkok, Thailand
| | - Adul Dulsuk
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Siriorn Loupha
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Kochnipa Kwawong
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Yaowaree Charoensawat
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | | | - Nicholas P J Day
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Center for Tropical Medicine and Global Health, University of Oxford, Oxford, United Kingdom
| | - Mary N Burtnick
- Department of Microbiology and Immunology, University of Nevada, Reno School of Medicine, Reno, Nevada, USA
| | - Paul J Brett
- Department of Microbiology and Immunology, University of Nevada, Reno School of Medicine, Reno, Nevada, USA
| | - T Eoin West
- Division of Pulmonary and Critical Care Medicine, Harborview Medical Center, and International Respiratory and Severe Illness Center, University of Washington, Seattle, WA, USA
| | - Narisara Chantratita
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
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21
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Khan MM, Chattagul S, Tran BQ, Freiberg JA, Nita-Lazar A, Shirtliff ME, Sermswan RW, Ernst RK, Goodlett DR. Temporal proteomic profiling reveals changes that support Burkholderia biofilms. Pathog Dis 2019; 77:ftz005. [PMID: 30759239 PMCID: PMC6482045 DOI: 10.1093/femspd/ftz005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2018] [Accepted: 02/12/2019] [Indexed: 12/14/2022] Open
Abstract
Melioidosis associated with opportunistic pathogen Burkholderia pseudomallei imparts a huge medical burden in Southeast Asia and Australia. At present there is no available human vaccine that protects against B. pseudomallei infection and antibiotic treatments are limited particularly for drug-resistant strains and bacteria in biofilm forms. Biofilm forming bacteria exhibit phenotypic features drastically different to their planktonic states, often exhibiting a diminished response to antimicrobial therapies. Our earlier work on global profiling of bacterial biofilms using transcriptomics and proteomics revealed transcript-decoupled protein abundance in bacterial biofilms. Here we employed reverse phase liquid chromatography tandem mass spectrometry (LC-MS/MS) to deduce temporal proteomic differences in planktonic and biofilm forms of Burkholderia thailandensis, which is weakly surrogate model of pathogenic B. pseudomallei as sharing a key element in genomic similarity. The proteomic analysis of B. thailandensis in biofilm versus planktonic states revealed that proteome changes support biofilm survival through decreased abundance of metabolic proteins while increased abundance of stress-related proteins. Interestingly, the protein abundance including for the transcription protein TEX, outer periplasmic TolB protein, and the exopolyphosphatase reveal adaption in bacterial biofilms that facilitate antibiotic tolerance through a non-specific mechanism. The present proteomics study of B. thailandensis biofilms provides a global snapshot of protein abundance differences and antimicrobial sensitivities in planktonic and sessile bacteria.
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Affiliation(s)
- Mohd M Khan
- University of Maryland School of Medicine, Baltimore, MD 21201, USA
- Laboratory of Immune System Biology (LISB), National Institute of Allergy and Infectious Diseases, National Institutes of Health (NIH), Bethesda, MD 20814, USA
| | - Supaksorn Chattagul
- Melioidosis Research Center, Khon Kaen University, Khon Kaen 40002, Thailand
- Department of Biochemistry, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, MD 21201, USA
| | - Bao Q Tran
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD 21201, USA
| | - Jeffrey A Freiberg
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, MD 21201, USA
| | - Aleksandra Nita-Lazar
- Laboratory of Immune System Biology (LISB), National Institute of Allergy and Infectious Diseases, National Institutes of Health (NIH), Bethesda, MD 20814, USA
| | - Mark E Shirtliff
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, MD 21201, USA
| | - Rasana W Sermswan
- Melioidosis Research Center, Khon Kaen University, Khon Kaen 40002, Thailand
- Department of Biochemistry, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand
| | - Robert K Ernst
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, MD 21201, USA
| | - David R Goodlett
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, MD 21201, USA
- International Centre for Cancer Vaccine Science, University of Gdansk, 80-308 Gdańsk, Poland
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22
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Burkholderia pseudomallei Δ tonB Δ hcp1 Live Attenuated Vaccine Strain Elicits Full Protective Immunity against Aerosolized Melioidosis Infection. mSphere 2019; 4:4/1/e00570-18. [PMID: 30602524 PMCID: PMC6315081 DOI: 10.1128/msphere.00570-18] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
In recent years, an increasing number of melioidosis cases have been reported in several regions where melioidosis is endemic and in areas where melioidosis had not commonly been diagnosed. Currently, the estimated burden of disease is around 165,000 new cases annually, including 89,000 cases that have fatal outcomes. This life-threatening infectious disease is caused by B. pseudomallei, which is classified as a Tier 1 select agent. Due to the high case fatality rate, intrinsic resistance to multiple antibiotic treatments, susceptibility to infection via the aerosol route, and potential use as a bioweapon, we have developed an effective live attenuated PBK001 vaccine capable of protecting against aerosolized melioidosis. Burkholderia pseudomallei is a Gram-negative facultative intracellular bacterium and the causative agent of melioidosis, a severe infectious disease found throughout the tropics. This organism is closely related to Burkholderia mallei, the etiological agent of glanders disease which primarily affects equines. These two pathogenic bacteria are classified as Tier 1 select agents due to their amenability to aerosolization, limited treatment options, and lack of an effective vaccine. We have previously successfully demonstrated the immunogenicity and protective efficacy of a live attenuated vaccine strain, B. malleiΔtonB Δhcp1 (CLH001). Thus, we applied this successful approach to the development of a similar vaccine against melioidosis by constructing the B. pseudomalleiΔtonB Δhcp1 (PBK001) strain. C57BL/6 mice were vaccinated intranasally with the live attenuated PBK001 strain and then challenged with wild-type B. pseudomallei K96243 by the aerosol route. Immunization with strain PBK001 resulted in full protection (100% survival) against acute aerosolized melioidosis with very low bacterial burden as observed in the lungs, livers, and spleens of immunized mice. PBK001 vaccination induced strong production of B. pseudomallei-specific serum IgG antibodies and both Th1 and Th17 CD4+ T cell responses. Further, humoral immunity appeared to be essential for vaccine-induced protection, whereas CD4+ and CD8+ T cells played a less direct immune role. Overall, PBK001 was shown to be an effective attenuated vaccine strain that activates a robust immune response and offers full protection against aerosol infection with B. pseudomallei. IMPORTANCE In recent years, an increasing number of melioidosis cases have been reported in several regions where melioidosis is endemic and in areas where melioidosis had not commonly been diagnosed. Currently, the estimated burden of disease is around 165,000 new cases annually, including 89,000 cases that have fatal outcomes. This life-threatening infectious disease is caused by B. pseudomallei, which is classified as a Tier 1 select agent. Due to the high case fatality rate, intrinsic resistance to multiple antibiotic treatments, susceptibility to infection via the aerosol route, and potential use as a bioweapon, we have developed an effective live attenuated PBK001 vaccine capable of protecting against aerosolized melioidosis.
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23
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Noreen Z, Jobichen C, Abbasi R, Seetharaman J, Sivaraman J, Bokhari H. Structural basis for the pathogenesis of Campylobacter jejuni Hcp1, a structural and effector protein of the Type VI Secretion System. FEBS J 2018; 285:4060-4070. [PMID: 30194714 DOI: 10.1111/febs.14650] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 08/17/2018] [Accepted: 09/03/2018] [Indexed: 12/22/2022]
Abstract
The Type VI Secretion System (T6SS) provides enhanced virulence to Campylobacter jejuni and has been associated with a high incidence of bloody diarrhea. The hemolysin-coregulated protein (Hcp)-the hallmark of the T6SS-can act as a structural and effector protein. Unlike other T6SS-harboring bacteria, which possess multiple Hcp proteins each performing different functions, C. jejuni possesses only one Hcp protein, and its structural and functional role has not been elucidated previously. Here, we report the structure and functional studies of Hcp from C. jejuni. We found similarities between the hexameric ring structure of Hcp-Cj and that of Hcp3 from Pseudomonas aeruginosa. Through functional studies, we showed two roles for Hcp-Cj that is, in cytotoxicity toward HepG2 cells and in biofilm formation in C. jejuni. In structure-based mutational analyses, we showed that an Arg-to-Ala mutation at position 30 within the extended loop results in a significant decrease in cytotoxicity, suggesting a role for this loop in binding to the host cell. However, this mutation does not affect its biofilm formation function. Collectively, this study supports the dual role of Hcp-Cj as a structural and effector protein in C. jejuni.
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Affiliation(s)
- Zobia Noreen
- Department of Biosciences, COMSATS University, Islamabad Campus, Islamabad, Pakistan
| | - Chacko Jobichen
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore
| | - Rashda Abbasi
- Institute of Biomedical and Genetic Engineering (IBGE), Islamabad, Pakistan
| | | | - J Sivaraman
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore
| | - Habib Bokhari
- Department of Biosciences, COMSATS University, Islamabad Campus, Islamabad, Pakistan
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24
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Schwemmlein N, Pippel J, Gazdag EM, Blankenfeldt W. Crystal Structures of R-Type Bacteriocin Sheath and Tube Proteins CD1363 and CD1364 From Clostridium difficile in the Pre-assembled State. Front Microbiol 2018; 9:1750. [PMID: 30127773 PMCID: PMC6088184 DOI: 10.3389/fmicb.2018.01750] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Accepted: 07/13/2018] [Indexed: 12/26/2022] Open
Abstract
Diffocins are high-molecular-weight phage tail-like bacteriocins (PTLBs) that some Clostridium difficile strains produce in response to SOS induction. Similar to the related R-type pyocins from Pseudomonas aeruginosa, R-type diffocins act as molecular puncture devices that specifically penetrate the cell envelope of other C. difficile strains to dissipate the membrane potential and kill the attacked bacterium. Thus, R-type diffocins constitute potential therapeutic agents to counter C. difficile-associated infections. PTLBs consist of rigid and contractile protein complexes. They are composed of a baseplate, receptor-binding tail fibers and an inner needle-like tube surrounded by a contractile sheath. In the mature particle, the sheath and tube structure form a complex network comprising up to 200 copies of a sheath and a tube protein each. Here, we report the crystal structures together with small angle X-ray scattering data of the sheath and tube proteins CD1363 (39 kDa) and CD1364 (16 kDa) from C. difficile strain CD630 in a monomeric pre-assembly form at 1.9 and 1.5 Å resolution, respectively. The tube protein CD1364 displays a compact fold and shares highest structural similarity with a tube protein from Bacillus subtilis but is remarkably different from that of the R-type pyocin from P. aeruginosa. The structure of the R-type diffocin sheath protein, on the other hand, is highly conserved. It contains two domains, whereas related members such as bacteriophage tail sheath proteins comprise up to four, indicating that R-type PTLBs may represent the minimal protein required for formation of a complete sheath structure. Comparison of CD1363 and CD1364 with structures of PTLBs and related assemblies suggests that several conformational changes are required to form complete assemblies. In the sheath, rearrangement of the flexible N- and C-terminus enables extensive interactions between the other subunits, whereas for the tube, such contacts are primarily established by mobile α-helices. Together, our results combined with information from structures of homologous assemblies allow constructing a preliminary model of the sheath and tube assembly from R-type diffocin.
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Affiliation(s)
- Nina Schwemmlein
- Structure and Function of Proteins, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Jan Pippel
- Structure and Function of Proteins, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Emerich-Mihai Gazdag
- Structure and Function of Proteins, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Wulf Blankenfeldt
- Structure and Function of Proteins, Helmholtz Centre for Infection Research, Braunschweig, Germany
- Institute for Biochemistry, Biotechnology and Bioinformatics, Technische Universität Braunschweig, Braunschweig, Germany
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25
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A Rapid Immunochromatography Test Based on Hcp1 Is a Potential Point-of-Care Test for Serological Diagnosis of Melioidosis. J Clin Microbiol 2018; 56:JCM.00346-18. [PMID: 29848565 PMCID: PMC6062804 DOI: 10.1128/jcm.00346-18] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 05/24/2018] [Indexed: 11/20/2022] Open
Abstract
Melioidosis is a fatal infectious disease caused by the environmental bacterium Burkholderia pseudomallei. It is highly endemic in Asia and northern Australia but neglected in many other tropical countries. Melioidosis is a fatal infectious disease caused by the environmental bacterium Burkholderia pseudomallei. It is highly endemic in Asia and northern Australia but neglected in many other tropical countries. Melioidosis patients have a wide range of clinical manifestations, and definitive diagnosis requires bacterial culture, which can be time-consuming. A reliable rapid serological tool is greatly needed for disease surveillance and diagnosis. We previously demonstrated by enzyme-linked immunosorbent assay (ELISA) that a hemolysin-coregulated protein (Hcp1) is a promising target for serodiagnosis of melioidosis. In this study, we developed a rapid immunochromatography test (ICT) using Hcp1 as the target antigen (Hcp1-ICT). We evaluated this test for specific antibody detection using serum samples obtained from 4 groups of human subjects, including the following: (i) 487 culture-confirmed melioidosis patients from four hospitals in northeast Thailand; (ii) 202 healthy donors from northeast Thailand; (iii) 90 U.S. healthy donors; and (iv) 207 patients infected with other organisms. Compared to culture results as a gold standard, the sensitivity of ICT for all hospitals was 88.3%. The specificities for Thai donors and U.S. donors were 86.1% and 100%, respectively, and the specificity for other infections was 91.8%. The results of the Hcp1-ICT demonstrated 92.4% agreement with the Hcp1-ELISA results with a kappa value of 0.829, indicating that the method is much improved compared with the current serological method, the indirect hemagglutination assay (IHA) (69.5% sensitivity and 67.6% specificity for Thais). The Hcp1-ICT represents a potential point-of-care (POC) test and may be used to replace the IHA for screening of melioidosis in hospitals as well as in resource-limited areas.
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26
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Wang N, Liu J, Pang M, Wu Y, Awan F, Liles MR, Lu C, Liu Y. Diverse roles of Hcp family proteins in the environmental fitness and pathogenicity of Aeromonas hydrophila Chinese epidemic strain NJ-35. Appl Microbiol Biotechnol 2018; 102:7083-7095. [PMID: 29862449 DOI: 10.1007/s00253-018-9116-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 05/14/2018] [Accepted: 05/18/2018] [Indexed: 01/19/2023]
Abstract
The type VI secretion system (T6SS) has been considered as a crucial factor in bacterial competition and virulence. The hemolysin co-regulated protein (Hcp) is the hallmark of T6SS. The secretion of Hcp in Aeromonas hydrophila Chinese epidemic strain NJ-35 indicated a functional T6SS. In this study, three copies of the hcp gene were identified in the genome of strain NJ-35. We targeted these Hcp family proteins for generating deletion mutants. These mutants showed varying levels in Hcp production, the interaction with other bacteria or eukaryotic cells, and bacterial virulence. Hcp1 was necessary for T6SS assembly and played a predominant role in the bacterial competition; Hcp2 negatively functioned in the biofilm formation and bacterial adhesion and was more involved in the A. hydrophila virulence in zebrafish and survival against the predation of Tetrahymena, and Hcp3 positively influenced the biofilm formation and bacterial adhesion. These findings illustrate that the T6SS of A. hydrophila NJ-35 is active, and the three Hcp family proteins take part in different processes in environmental adaptation and virulence of this bacterium. This study will provide valuable insights into our understanding of microbial interactions and thus contribute to a broader effort to manipulate these interactions for therapeutic or environmental benefit.
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Affiliation(s)
- Nannan Wang
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Jin Liu
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Maoda Pang
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Lab of Food Quality and Safety of Jiangsu Province-State Key Laboratory Breeding Base, Institute of Food Safety and Nutrition, Jiangsu Academy of Agricultural Sciences, Nanjing, China
| | - Yafeng Wu
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Jiangsu Center for Control and Prevention of Aquatic Animal Infectious Diseases, Nanjing, China
| | - Furqan Awan
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Mark R Liles
- Department of Biological Sciences, Auburn University, Auburn, USA
| | - Chengping Lu
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Yongjie Liu
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.
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27
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Duong LT, Schwarz S, Gross H, Breitbach K, Hochgräfe F, Mostertz J, Eske-Pogodda K, Wagner GE, Steinmetz I, Kohler C. GvmR - A Novel LysR-Type Transcriptional Regulator Involved in Virulence and Primary and Secondary Metabolism of Burkholderia pseudomallei. Front Microbiol 2018; 9:935. [PMID: 29867844 PMCID: PMC5964159 DOI: 10.3389/fmicb.2018.00935] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 04/23/2018] [Indexed: 01/22/2023] Open
Abstract
Burkholderia pseudomallei is a soil-dwelling bacterium able to survive not only under adverse environmental conditions, but also within various hosts which can lead to the disease melioidosis. The capability of B. pseudomallei to adapt to environmental changes is facilitated by the large number of regulatory proteins encoded by its genome. Among them are more than 60 uncharacterized LysR-type transcriptional regulators (LTTRs). Here we analyzed a B. pseudomallei mutant harboring a transposon in the gene BPSL0117 annotated as a LTTR, which we named gvmR (globally acting virulence and metabolism regulator). The gvmR mutant displayed a growth defect in minimal medium and macrophages in comparison with the wild type. Moreover, disruption of gvmR rendered B. pseudomallei avirulent in mice indicating a critical role of GvmR in infection. These defects of the mutant were rescued by ectopic expression of gvmR. To identify genes whose expression is modulated by GvmR, global transcriptome analysis of the B. pseudomallei wild type and gvmR mutant was performed using whole genome tiling microarrays. Transcript levels of 190 genes were upregulated and 141 genes were downregulated in the gvmR mutant relative to the wild type. Among the most downregulated genes in the gvmR mutant were important virulence factor genes (T3SS3, T6SS1, and T6SS2), which could explain the virulence defect of the gvmR mutant. In addition, expression of genes related to amino acid synthesis, glyoxylate shunt, iron-sulfur cluster assembly, and syrbactin metabolism (secondary metabolite) was decreased in the mutant. On the other hand, inactivation of GvmR increased expression of genes involved in pyruvate metabolism, ATP synthesis, malleobactin, and porin genes. Quantitative real-time PCR verified the differential expression of 27 selected genes. In summary, our data show that GvmR acts as an activating and repressing global regulator that is required to coordinate expression of a diverse set of metabolic and virulence genes essential for the survival in the animal host and under nutrient limitation.
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Affiliation(s)
- Linh Tuan Duong
- Friedrich Loeffler Institute of Medical Microbiology, University Medicine Greifswald, Greifswald, Germany
| | - Sandra Schwarz
- Interfaculty Institute of Microbiology and Infection Medicine Tübingen, University of Tübingen, Tübingen, Germany
| | - Harald Gross
- Department of Pharmaceutical Biology, Pharmaceutical Institute, Eberhard Karls University of Tübingen, Tübingen, Germany.,German Centre for Infection Research, Partner Site Tübingen, Tübingen, Germany
| | - Katrin Breitbach
- Friedrich Loeffler Institute of Medical Microbiology, University Medicine Greifswald, Greifswald, Germany
| | - Falko Hochgräfe
- Competence Center Functional Genomics, Junior Research Group Pathoproteomics, University of Greifswald, Greifswald, Germany
| | - Jörg Mostertz
- Competence Center Functional Genomics, Junior Research Group Pathoproteomics, University of Greifswald, Greifswald, Germany
| | - Kristin Eske-Pogodda
- Friedrich Loeffler Institute of Medical Microbiology, University Medicine Greifswald, Greifswald, Germany
| | - Gabriel E Wagner
- Institute of Hygiene, Microbiology and Environmental Medicine, Medical University of Graz, Graz, Austria
| | - Ivo Steinmetz
- Friedrich Loeffler Institute of Medical Microbiology, University Medicine Greifswald, Greifswald, Germany.,Institute of Hygiene, Microbiology and Environmental Medicine, Medical University of Graz, Graz, Austria
| | - Christian Kohler
- Friedrich Loeffler Institute of Medical Microbiology, University Medicine Greifswald, Greifswald, Germany
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28
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Ma J, Sun M, Pan Z, Song W, Lu C, Yao H. Three Hcp homologs with divergent extended loop regions exhibit different functions in avian pathogenic Escherichia coli. Emerg Microbes Infect 2018; 7:49. [PMID: 29593238 PMCID: PMC5874247 DOI: 10.1038/s41426-018-0042-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 01/22/2018] [Accepted: 01/23/2018] [Indexed: 11/17/2022]
Abstract
Type VI secretion systems (T6SSs) contribute to the pathogenicity of avian pathogenic Escherichia coli (APEC), one of the leading causative agents of sepsis and meningitis in poultry. The Hcp protein is a core component of the T6SS tail tube and acts as an exported receptor and a chaperone of effectors. In this study, four distinct Hcp types (Ia, Ib, IIa, and IIb) were designated in Gram-negative bacteria, three of which were widely distributed in APEC. We detected divergence in transcription levels among three hcp clusters in 50% duck serum and demonstrated that hcp1 was upregulated by relieving Fur repression. Further analyses revealed that the host serum could activate the hcp2B operon by H-NS derepression to transcribe the downstream xmtU/xmtV pair for inter-bacterial antagonism. Notably, in a structural analysis based on the genetic classification, Hcp proteins exhibited significant differences in the extended loop regions, suggesting that these regions were related to their functional properties. Indeed, the variant region Vs2 (Loop L2, 3) in Hcp1 and Hcp2B was essential for the delivery of antibacterial effectors and the inhibition of macrophage phagocytosis. Further analyses using a duck model indicated that these Hcps play different roles in the pathogenic processes of APEC and immunoprotection. These results indicated that the functional differentiation of Hcp homologs was driven by differences in transcriptional regulation, extended loop regions, and effector delivery.
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Affiliation(s)
- Jiale Ma
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China.,Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing, 210095, China
| | - Min Sun
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China.,Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing, 210095, China
| | - Zihao Pan
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China.,Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing, 210095, China
| | - Wenchao Song
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China.,Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing, 210095, China
| | - Chengping Lu
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China.,Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing, 210095, China
| | - Huochun Yao
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China. .,Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing, 210095, China.
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Bacteriophage T5 tail tube structure suggests a trigger mechanism for Siphoviridae DNA ejection. Nat Commun 2017; 8:1953. [PMID: 29209037 PMCID: PMC5717097 DOI: 10.1038/s41467-017-02049-3] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 11/02/2017] [Indexed: 11/29/2022] Open
Abstract
The vast majority of phages, bacterial viruses, possess a tail ensuring host recognition, cell wall perforation and safe viral DNA transfer from the capsid to the host cytoplasm. Long flexible tails are formed from the tail tube protein (TTP) polymerised as hexameric rings around and stacked along the tape measure protein (TMP). Here, we report the crystal structure of T5 TTP pb6 at 2.2 Å resolution. Pb6 is unusual in forming a trimeric ring, although structure analysis reveals homology with all classical TTPs and related tube proteins of bacterial puncturing devices (type VI secretion system and R-pyocin). Structures of T5 tail tubes before and after interaction with the host receptor were determined by cryo-electron microscopy at 6 Å resolution. Comparison of these two structures reveals that host-binding information is not propagated to the capsid through conformational changes in the tail tube, suggesting a role of the TMP in this information transduction process. Host cell recognition is mediated by the phage tail tip proteins, which then triggers viral genome delivery via the phage tail. Here, the authors combine crystallography and cryoEM to structurally characterise the bacteriophage T5 tail tube structure before and after interaction with its host receptor.
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Lin QP, Gao ZQ, Geng Z, Zhang H, Dong YH. Crystal structure of the putative cytoplasmic protein STM0279 (Hcp2) from Salmonella typhimurium. ACTA CRYSTALLOGRAPHICA SECTION F-STRUCTURAL BIOLOGY COMMUNICATIONS 2017; 73:463-468. [PMID: 28777089 DOI: 10.1107/s2053230x17010512] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Accepted: 07/15/2017] [Indexed: 11/10/2022]
Abstract
STM0279 is a putative cytoplasmic protein from Salmonella typhimurium and was recently renamed haemolysin co-regulated protein 2 (Hcp2), with the neighbouring STM0276 being Hcp1. Both of them are encoded by the type VI secretion system (T6SS) of the Salmonella pathogenicity island 6 (SPI-6) locus and have high sequence identity. The Hcp proteins may function as a vital component of the T6SS nanotube and as a transporter and chaperone of diverse effectors from the bacterial T6SS. In this study, the crystal structure and the oligomeric state in solution of Hcp2 from S. typhimurium (StHcp2) were investigated. The crystal structure refined to 3.0 Å resolution showed that the protein is composed of a β-barrel domain with extended loops and can form hexameric rings as observed in known Hcp homologues. Mutation of the extended loop was found to partly destabilize the hexameric conformation into monomers or cause the production of inclusion bodies, suggesting it has an important role in hexameric ring formation.
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Affiliation(s)
- Qing Peng Lin
- School of Life Sciences, University of Science and Technology of China, Hefei 230027, People's Republic of China
| | - Zeng Qiang Gao
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, People's Republic of China
| | - Zhi Geng
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, People's Republic of China
| | - Heng Zhang
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, People's Republic of China
| | - Yu Hui Dong
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, People's Republic of China
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Pumirat P, Vanaporn M, Boonyuen U, Indrawattana N, Rungruengkitkun A, Chantratita N. Effects of sodium chloride on heat resistance, oxidative susceptibility, motility, biofilm and plaque formation of Burkholderia pseudomallei. Microbiologyopen 2017. [PMID: 28643413 PMCID: PMC5552950 DOI: 10.1002/mbo3.493] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Burkholderia pseudomallei is an environmental saprophyte and the causative agent of melioidosis, a severe infectious disease prevalent in tropical areas, including southeast Asia and northern Australia. In Thailand, the highest incidence of melioidosis is in the northeast region, where saline soil and water are abundant. We hypothesized that B. pseudomallei develops an ability to thrive in saline conditions and gains a selective ecological advantage over other soil-dwelling microorganisms. However, little is known about how an elevated NaCl concentration affects survival and adaptive changes in this pathogen. In this study, we examined the adaptive changes in six isolates of B. pseudomallei after growth in Luria-Bertani medium containing different concentrations of NaCl at 37°C for 6 hr. The bacteria were then investigated for resistance to heat at 50°C and killing by hydrogen peroxide (H2 O2 ). In addition, flagellar production, biofilm formation, and the plaque formation efficiency of B. pseudomallei after culture in saline conditions were observed. In response to exposure to 150 and 300 mmol L-1 NaCl, all B. pseudomallei isolates showed significantly increased thermal tolerance, oxidative resistance, and plaque-forming efficiency. However, NaCl exposure notably decreased the number of B. pseudomallei flagella. Taken together, these results provide insight into the adaptations of B. pseudomallei that might be crucial for survival and persistence in the host and/or endemic environments with high salinity.
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Affiliation(s)
- Pornpan Pumirat
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Muthita Vanaporn
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Usa Boonyuen
- Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Nitaya Indrawattana
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Amporn Rungruengkitkun
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Narisara Chantratita
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
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Pumpuang A, Dunachie SJ, Phokrai P, Jenjaroen K, Sintiprungrat K, Boonsilp S, Brett PJ, Burtnick MN, Chantratita N. Comparison of O-polysaccharide and hemolysin co-regulated protein as target antigens for serodiagnosis of melioidosis. PLoS Negl Trop Dis 2017; 11:e0005499. [PMID: 28358816 PMCID: PMC5395236 DOI: 10.1371/journal.pntd.0005499] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 04/18/2017] [Accepted: 03/17/2017] [Indexed: 12/22/2022] Open
Abstract
Background Melioidosis is a severe disease caused by Burkholderia pseudomallei. Clinical manifestations are diverse and acute infections require immediate treatment with effective antibiotics. While culture is the current diagnostic standard, it is time-consuming and has low sensitivity. In endemic areas, inaccessibility to biosafety level 3 facilities and a lack of good serodiagnostic tools can impede diagnosis and disease surveillance. Recent studies have suggested that O-polysaccharide (OPS) and hemolysin co-regulated protein 1 (Hcp1) are promising target antigens for serodiagnosis of melioidosis. Methodology/Principle findings We evaluated rapid ELISAs using crude antigens, purified OPS and Hcp1 to measure antibody levels in three sets of sera: (i) 419 serum samples from melioidosis patients, Thai and U.S. healthy donors, (ii) 120 serum samples from patients with other bacterial infections, and (iii) 423 serum samples from 200 melioidosis patients obtained upon admission and at 12 and 52 weeks post-recovery. We observed significantly higher antibody levels using the crude antigen prepared from wild type B. pseudomallei K96243 compared to that of an OPS-mutant. The areas under receiver operator characteristics (AUROCCs) for diagnosis were compared for individual Hcp1-ELISA or OPS-ELISA or combined Hcp1/OPS-ELISA. For Thai donors, AUROCCs were highest and comparable between the Hcp1-ELISA and the combined Hcp1/OPS-ELISA (0.95 versus 0.94). For U.S. donors, the AUROCC was highest for the combined Hcp1/OPS-ELISA (0.96). Significantly higher seropositivity was observed in diabetic patients compared to those without diabetes for both the Hcp1-ELISA (87.3% versus 69.7%) and OPS-ELISA (88.1% versus 60.6%). Although antibody levels for Hcp1 were highest upon admission, the titers declined by week 52 post-recovery. Conclusions/Significance Hcp1 and OPS are promising candidates for serodiagnosis of melioidosis in different groups of patients. The Hcp1-ELISA performed better than the OPS-ELISA in endemic areas, thus, Hcp1 represents a promising target antigen for the development of POC tests for acute melioidosis. Melioidosis, caused by Burkholderia pseudomallei, is a life-threatening infection endemic in tropical countries. Definitive diagnosis of melioidosis relies upon bacterial culture which requires suitable laboratory facilities and reliable antibody testing. To obtain an effective target antigen for use in a simple point-of-care (POC) test, rapid ELISAs using crude B. pseudomallei antigen preparations or purified O-polysaccharide (OPS) and hemolysin co-regulated protein (Hcp1) were compared using serum samples from three large collections obtained from melioidosis patients and patients with other bacterial infections. We detected high levels of antibodies to Hcp1 and OPS in serum from melioidosis patients upon admission and showed that anti-Hcp1 levels declined post-recovery. When serum samples from endemic areas were tested, the performance of the Hcp1-ELISA and combined Hcp1/OPS-ELISA were higher than the OPS-ELISA. When serum from non-endemic areas was tested, the combined Hcp1/OPS-ELISA gave the highest performance. Both the OPS- and Hcp1-based ELISAs were useful for detection of antibodies in various groups of patients including diabetics. Since anti-Hcp1 titers in melioidosis patient serum were higher than anti-OPS titers, Hcp1 is an attractive candidate for further development of a rapid POC test for use in endemic areas.
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Affiliation(s)
- Apinya Pumpuang
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Department of Clinical Pathology, Faculty of Medicine, Vajira Hospital, Navamindradhiraj University, Bangkok, Thailand
| | - Susanna J. Dunachie
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine & Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Phornpun Phokrai
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Kemajittra Jenjaroen
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Kitisak Sintiprungrat
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Siriphan Boonsilp
- Department of Clinical Pathology, Faculty of Medicine, Vajira Hospital, Navamindradhiraj University, Bangkok, Thailand
| | - Paul J. Brett
- Department of Microbiology and Immunology, University of South Alabama, Mobile, Alabama, United States of America
| | - Mary N. Burtnick
- Department of Microbiology and Immunology, University of South Alabama, Mobile, Alabama, United States of America
| | - Narisara Chantratita
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- * E-mail:
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Willcocks SJ, Denman CC, Atkins HS, Wren BW. Intracellular replication of the well-armed pathogen Burkholderia pseudomallei. Curr Opin Microbiol 2016; 29:94-103. [DOI: 10.1016/j.mib.2015.11.007] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 11/27/2015] [Accepted: 11/30/2015] [Indexed: 12/31/2022]
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Spínola-Amilibia M, Davó-Siguero I, Ruiz FM, Santillana E, Medrano FJ, Romero A. The structure of VgrG1 fromPseudomonas aeruginosa, the needle tip of the bacterial type VI secretion system. ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY 2016; 72:22-33. [DOI: 10.1107/s2059798315021142] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 11/06/2015] [Indexed: 11/10/2022]
Abstract
The type VI secretion system (T6SS) is a mechanism that is commonly used by pathogenic bacteria to infect host cells and for survival in competitive environments. This system assembles on a core baseplate and elongates like a phage puncturing device; it is thought to penetrate the target membrane and deliver effectors into the host or competing bacteria. Valine–glycine repeat protein G1 (VgrG1) forms the spike at the tip of the elongating tube formed by haemolysin co-regulated protein 1 (Hcp1); it is structurally similar to the T4 phage (gp27)3–(gp5)3puncturing complex. Here, the crystal structure of full-length VgrG1 fromPseudomonas aeruginosais reported at a resolution of 2.0 Å, which through a trimeric arrangement generates a needle-like shape composed of two main parts, the head and the spike, connectedviaa small neck region. The structure reveals several remarkable structural features pointing to the possible roles of the two main segments of VgrG1: the head as a scaffold cargo domain and the β-roll spike with implications in the cell-membrane puncturing process and as a carrier of cognate toxins.
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Wong J, Chen Y, Gan YH. Host Cytosolic Glutathione Sensing by a Membrane Histidine Kinase Activates the Type VI Secretion System in an Intracellular Bacterium. Cell Host Microbe 2015; 18:38-48. [PMID: 26094804 DOI: 10.1016/j.chom.2015.06.002] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 04/26/2015] [Accepted: 06/02/2015] [Indexed: 12/17/2022]
Abstract
Type VI secretion systems (T6SSs) are major virulence mechanisms in many Gram-negative bacteria, but the physiological signals that activate them are not well understood. The T6SS1 of Burkholderia pseudomallei is essential for pathogenesis in mammalian hosts and is only expressed when the bacterium is intracellular. We found that signals for T6SS1 activation reside in the host cytosol. Through site-directed mutagenesis and biochemical studies, we identified low molecular weight thiols, particularly glutathione, as the signal sensed by a periplasmic cysteine residue (C62) on the histidine kinase sensor VirA. Upon glutathione exposure, dimeric VirA is converted to monomers via reduction at C62. When glutathione in the host was depleted, T6SS1 expression was abrogated, and bacteria could no longer induce multinucleate giant cell formation, the hallmark of T6SS1 function. Therefore, intracellular bacteria exploit the abundance of glutathione in host cytosol as a signal for expression of virulence at the appropriate time and place.
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Affiliation(s)
- Jocelyn Wong
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore. MD7, 8 Medical Drive, Singapore 117597, Singapore
| | - Yahua Chen
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore. MD7, 8 Medical Drive, Singapore 117597, Singapore
| | - Yunn-Hwen Gan
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore. MD7, 8 Medical Drive, Singapore 117597, Singapore.
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