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Yu H, Gu X, Wang D, Wang Z. Brucella infection and Toll-like receptors. Front Cell Infect Microbiol 2024; 14:1342684. [PMID: 38533384 PMCID: PMC10963510 DOI: 10.3389/fcimb.2024.1342684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Accepted: 01/17/2024] [Indexed: 03/28/2024] Open
Abstract
Brucella consists of gram-negative bacteria that have the ability to invade and replicate in professional and non-professional phagocytes, and its prolonged persistence in the host leads to brucellosis, a serious zoonosis. Toll-like receptors (TLRs) are the best-known sensors of microorganisms implicated in the regulation of innate and adaptive immunity. In particular, TLRs are transmembrane proteins with a typical structure of an extracellular leucine-rich repeat (LRR) region and an intracellular Toll/interleukin-1 receptor (TIR) domain. In this review, we discuss Brucella infection and the aspects of host immune responses induced by pathogens. Furthermore, we summarize the roles of TLRs in Brucella infection, with substantial emphasis on the molecular insights into its mechanisms of action.
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Affiliation(s)
- Hui Yu
- Inner Mongolia Key Laboratory of Disease-Related Biomarkers, The Second Affiliated Hospital, Baotou Medical College, Baotou, China
- School of Basic Medicine, Baotou Medical College, Baotou, China
| | - Xinyi Gu
- The College of Medical Technology, Shanghai University of Medicine & Health Sciences, Shanghai, China
| | - Danfeng Wang
- The College of Medical Technology, Shanghai University of Medicine & Health Sciences, Shanghai, China
| | - Zhanli Wang
- Inner Mongolia Key Laboratory of Disease-Related Biomarkers, The Second Affiliated Hospital, Baotou Medical College, Baotou, China
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2
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Achi SC, Karimilangi S, Lie D, Sayed IM, Das S. The WxxxE proteins in microbial pathogenesis. Crit Rev Microbiol 2023; 49:197-213. [PMID: 35287539 PMCID: PMC9737147 DOI: 10.1080/1040841x.2022.2046546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2021] [Revised: 02/10/2022] [Accepted: 02/19/2022] [Indexed: 12/14/2022]
Abstract
Effector proteins secreted by pathogens modulate various host cellular processes and help in bacterial pathogenesis. Some of these proteins, injected by enteric pathogens via Type Three Secretion System (T3SS) were grouped together based on a conserved signature motif (WxxxE) present in them. The presence of WxxxE motif is not limited to effectors released by enteric pathogens or the T3SS but has been detected in non-enteric pathogens, plant pathogens and in association with Type II and Type IV secretion systems. WxxxE effectors are involved in actin organization, inflammation regulation, vacuole or tubule formation, endolysosomal signalling regulation, tight junction disruption, and apoptosis. The WxxxE sequence has also been identified in TIR [Toll/interleukin-1 (IL-1) receptor] domains of bacteria and host. In the present review, we have focussed on the established and predicted functions of WxxxE effectors secreted by several pathogens, including enteric, non-enteric, and plant pathogens.
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Affiliation(s)
| | - Sareh Karimilangi
- Department of Pathology, University of California San Diego, La Jolla, CA, USA
| | - Dominique Lie
- Department of Pathology, University of California San Diego, La Jolla, CA, USA
| | - Ibrahim M. Sayed
- Department of Pathology, University of California San Diego, La Jolla, CA, USA
| | - Soumita Das
- Department of Pathology, University of California San Diego, La Jolla, CA, USA
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3
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Characterization of the novel temperate Staphylococcus haemolyticus phage IME1365_01. Arch Virol 2023; 168:41. [PMID: 36609576 DOI: 10.1007/s00705-022-05650-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2022] [Accepted: 10/03/2022] [Indexed: 01/09/2023]
Abstract
The presence of a novel functional prophage, IME1365_01, was predicted from bacterial high-throughput sequencing data and then successfully induced from Staphylococcus haemolyticus by mitomycin C treatment. Transmission electron microscopy showed that phage IME1365_01 has an icosahedral head (43 nm in diameter) and a long tail (172 nm long). This phage possesses a double-stranded DNA genome of 44,875 bp with a G+C content of 35.35%. A total of 63 putative open reading frames (ORFs) were identified in its genome. BLASTn analysis revealed that IME1365_01 is similar to Staphylococcus phage vB_SepS_E72, but with a genome homology coverage of only 26%. The phage genome does not have fixed termini. In ORF24 of phage IME1365_01, a conserved Toll-interleukin-1 receptor domain of the TIR_2 superfamily (accession no. c123749) is located at its N-terminus, and this might serve as a component of an anti-bacterial system. In conclusion, we developed a platform to obtain active temperate phage from prediction, identification, and induction from its bacterial host. After mass screening using this platform, numerous temperate phages and their innate anti-bacterial elements can provide extensive opportunities for therapy against bacterial (especially drug-resistant bacterial) infections.
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4
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Sarkar A, Kumari N, Mukherjee P. The curious case of SARM1: Dr. Jekyll and Mr. Hyde in cell death and immunity? FEBS J 2023; 290:340-358. [PMID: 34710262 DOI: 10.1111/febs.16256] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 09/21/2021] [Accepted: 10/27/2021] [Indexed: 02/06/2023]
Abstract
Sterile alpha and toll/interleukin-1 receptor motif-containing protein 1 (SARM1) was first identified as a novel ortholog of Drosophila protein CG7915 and was subsequently placed as the fifth member of the human TIR-containing adaptor protein. SARM1 holds a unique position in this family where, unlike other members, it downregulates NFκB activity in response to immunogenic stimulation, interacts with another member of the family, TRIF, to negatively regulate its function, and it also mediates cell death responses. Over the past decade, SARM1 has emerged as one of the primary mediators of programmed axonal degeneration and this robust regulation of axonal degeneration-especially in models of peripheral neuropathy and traumatic injury-makes it an attractive target for therapeutic intervention. The TIR domain of SARM1 possesses an intrinsic NADase activity resulting in cellular energy deficits within the axons, a striking deviation from its other family members of human TLR adaptors. Interestingly, the TIR NADase activity, as seen in SARM1, is also observed in several prokaryotic TIR-containing proteins where they are involved in immune evasion once within the host. Although the immune function of SARM1 is yet to be conclusively discerned, this closeness in function with the prokaryotic TIR-domain containing proteins, places it at an interesting juncture of evolution raising questions about its origin and function in cell death and immunity. In this review, we discuss how a conserved immune adaptor protein like SARM1 switches to a pro-neurodegenerative function and the evolutionarily significance of the process.
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Affiliation(s)
- Ankita Sarkar
- School of Biotechnology, Presidency University, Kolkata, West Bengal, India
| | - Nripa Kumari
- School of Biotechnology, Presidency University, Kolkata, West Bengal, India
| | - Piyali Mukherjee
- School of Biotechnology, Presidency University, Kolkata, West Bengal, India
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5
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Manik MK, Shi Y, Li S, Zaydman MA, Damaraju N, Eastman S, Smith TG, Gu W, Masic V, Mosaiab T, Weagley JS, Hancock SJ, Vasquez E, Hartley-Tassell L, Kargios N, Maruta N, Lim BYJ, Burdett H, Landsberg MJ, Schembri MA, Prokes I, Song L, Grant M, DiAntonio A, Nanson JD, Guo M, Milbrandt J, Ve T, Kobe B. Cyclic ADP ribose isomers: Production, chemical structures, and immune signaling. Science 2022; 377:eadc8969. [PMID: 36048923 DOI: 10.1126/science.adc8969] [Citation(s) in RCA: 44] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Cyclic adenosine diphosphate (ADP)-ribose (cADPR) isomers are signaling molecules produced by bacterial and plant Toll/interleukin-1 receptor (TIR) domains via nicotinamide adenine dinucleotide (oxidized form) (NAD+) hydrolysis. We show that v-cADPR (2'cADPR) and v2-cADPR (3'cADPR) isomers are cyclized by O-glycosidic bond formation between the ribose moieties in ADPR. Structures of 2'cADPR-producing TIR domains reveal conformational changes that lead to an active assembly that resembles those of Toll-like receptor adaptor TIR domains. Mutagenesis reveals a conserved tryptophan that is essential for cyclization. We show that 3'cADPR is an activator of ThsA effector proteins from the bacterial antiphage defense system termed Thoeris and a suppressor of plant immunity when produced by the effector HopAM1. Collectively, our results reveal the molecular basis of cADPR isomer production and establish 3'cADPR in bacteria as an antiviral and plant immunity-suppressing signaling molecule.
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Affiliation(s)
- Mohammad K Manik
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
- Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Yun Shi
- Institute for Glycomics, Griffith University, Southport, QLD 4222, Australia
| | - Sulin Li
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
- Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Mark A Zaydman
- Department of Pathology and Immunology, Washington University School of Medicine in St. Louis, St. Louis, MO 63100, USA
| | - Neha Damaraju
- Department of Developmental Biology, Washington University School of Medicine in St. Louis, St. Louis, MO 63100, USA
- Department of Genetics, Washington University School of Medicine in St. Louis, St. Louis, MO 63100, USA
| | - Samuel Eastman
- Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln, NE 68583, USA
| | - Thomas G Smith
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
| | - Weixi Gu
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
- Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Veronika Masic
- Institute for Glycomics, Griffith University, Southport, QLD 4222, Australia
| | - Tamim Mosaiab
- Institute for Glycomics, Griffith University, Southport, QLD 4222, Australia
| | - James S Weagley
- Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
| | - Steven J Hancock
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
- Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Eduardo Vasquez
- Institute for Glycomics, Griffith University, Southport, QLD 4222, Australia
| | | | - Nestoras Kargios
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
| | - Natsumi Maruta
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
- Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Bryan Y J Lim
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
- Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Hayden Burdett
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
- Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Michael J Landsberg
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
- Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Mark A Schembri
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
- Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Ivan Prokes
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK
| | - Lijiang Song
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK
| | - Murray Grant
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
| | - Aaron DiAntonio
- Department of Pathology and Immunology, Washington University School of Medicine in St. Louis, St. Louis, MO 63100, USA
- Department of Developmental Biology, Washington University School of Medicine in St. Louis, St. Louis, MO 63100, USA
| | - Jeffrey D Nanson
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
- Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Ming Guo
- Department of Agronomy and Horticulture, University of Nebraska-Lincoln, Lincoln, NE 68583, USA
| | - Jeffrey Milbrandt
- Department of Pathology and Immunology, Washington University School of Medicine in St. Louis, St. Louis, MO 63100, USA
| | - Thomas Ve
- Institute for Glycomics, Griffith University, Southport, QLD 4222, Australia
| | - Bostjan Kobe
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
- Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD 4072, Australia
- The University of Queensland, Institute for Molecular Bioscience, Brisbane, QLD 4072, Australia
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6
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Mugunthan SP, Harish MC. In silico structural homology modeling and functional characterization of Mycoplasma gallisepticum variable lipoprotein hemagglutin proteins. Front Vet Sci 2022; 9:943831. [PMID: 35990271 PMCID: PMC9386052 DOI: 10.3389/fvets.2022.943831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2022] [Accepted: 07/01/2022] [Indexed: 11/13/2022] Open
Abstract
Mycoplasma gallisepticum variable lipoprotein hemagglutin (vlhA) proteins are crucial for immune evasion from the host cells, permitting the persistence and survival of the pathogen. However, the exact molecular mechanism behind the immune evasion function is still not clear. In silico physiochemical analysis, domain analysis, subcellular localization, and homology modeling studies have been carried out to predict the structural and functional properties of these proteins. The outcomes of this study provide significant preliminary data for understanding the immune evasion by vlhA proteins. In this study, we have reported the primary, secondary, and tertiary structural characteristics and subcellular localization, presence of the transmembrane helix and signal peptide, and functional characteristics of vlhA proteins from M. gallisepticum strain R low. The results show variation between the structural and functional components of the proteins, signifying the role and diverse molecular mechanisms in functioning of vlhA proteins in host immune evasion. Moreover the 3D structure predicted in this study will pave a way for understanding vlhA protein function and its interaction with other molecules to undergo immune evasion. This study forms the basis for future experimental studies improving our understanding in the molecular mechanisms used by vlhA proteins.
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7
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Johnson CM, Harden MM, Grossman AD. Interactions between mobile genetic elements: An anti-phage gene in an integrative and conjugative element protects host cells from predation by a temperate bacteriophage. PLoS Genet 2022; 18:e1010065. [PMID: 35157704 PMCID: PMC8880864 DOI: 10.1371/journal.pgen.1010065] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 02/25/2022] [Accepted: 02/01/2022] [Indexed: 01/21/2023] Open
Abstract
Most bacterial genomes contain horizontally acquired and transmissible mobile genetic elements, including temperate bacteriophages and integrative and conjugative elements. Little is known about how these elements interact and co-evolved as parts of their host genomes. In many cases, it is not known what advantages, if any, these elements provide to their bacterial hosts. Most strains of Bacillus subtilis contain the temperate phage SPß and the integrative and conjugative element ICEBs1. Here we show that the presence of ICEBs1 in cells protects populations of B. subtilis from predation by SPß, likely providing selective pressure for the maintenance of ICEBs1 in B. subtilis. A single gene in ICEBs1 (yddK, now called spbK for SPß killing) was both necessary and sufficient for this protection. spbK inhibited production of SPß, during both activation of a lysogen and following de novo infection. We found that expression spbK, together with the SPß gene yonE constitutes an abortive infection system that leads to cell death. spbK encodes a TIR (Toll-interleukin-1 receptor)-domain protein with similarity to some plant antiviral proteins and animal innate immune signaling proteins. We postulate that many uncharacterized cargo genes in ICEs may confer selective advantage to cells by protecting against other mobile elements. Chromosomes from virtually all organisms contain genes that were horizontally acquired. In bacteria, many of the horizontally acquired genes are located in mobile genetic elements, elements that promote their own transfer from one cell to another. These elements include viruses and conjugative elements that are parts of the host genome and they can contain genes involved in metabolism, pathogenesis, symbiosis, and antibiotic resistances. Interactions between these elements are poorly understood. Furthermore, the majority of these elements confer no obvious benefit to host cells. We found that the presence of an integrative and conjugative element (ICE) in a bacterial genome protects host cells from predation by a bacteriophage (virus). There is a single gene in the integrative and conjugative element that confers this protection, and one gene in the bacteriophage that likely works together with the ICE gene. When expressed at the same time, these two genes cause cell death, before functional viruses can be made and released to kill other cells. We postulate that other ICEs may confer selective advantage to their host cells by protecting against other mobile elements.
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Affiliation(s)
- Christopher M. Johnson
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - M. Michael Harden
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Alan D. Grossman
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
- * E-mail:
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8
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Tang HP, Huang C, Hu CB, Li H, Shao T, Ji JF, Bai J, Fan DD, Lin AF, Xiang LX, Shao JZ. Inhibitory Role of an Aeromonas hydrophila TIR Domain Effector in Antibacterial Immunity by Targeting TLR Signaling Complexes in Zebrafish. Front Microbiol 2021; 12:694081. [PMID: 34305858 PMCID: PMC8297594 DOI: 10.3389/fmicb.2021.694081] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 06/15/2021] [Indexed: 12/16/2022] Open
Abstract
The Toll/interleukin-1 receptor (TIR) domain is a structural unit responsible for the assembly of signal protein complexes in Toll-like receptor (TLR) and interleukin-1 receptor signaling pathways. TIR domain homologs are found in a considerable number of bacteria and enhance bacterial infection and survival in host organisms. However, whether TIR domain homologs exist in Aeromonas hydrophila, a ubiquitous waterborne bacterium in aquatic environments, remains poorly understood. In this study, a TIR domain protein (TcpAh) was identified from A. hydrophila JBN2301. TIR domain of TcpAh is highly homologous to the counterpart domains in TLRs and myeloid differentiation factor 88 (MyD88). The zebrafish infected with mutant A. hydrophila with tcpAh deletion had a remarkably lower mortality than those infected with the wild-type strain. This result suggests that TcpAh is a crucial virulence factor for A. hydrophila infection. TcpAh exhibited a strong ability to associate with MyD88, tumor necrosis factor receptor-associated factor 3 (TRAF3) and TRAF-associated NF-κB activator-binding kinase 1 (TBK1) in TIR-TIR, TIR-Death domain (DD), and other alternative interactions. This finding suggests that TcpAh extensively interferes with MyD88 and TIR domain-containing adapter inducing interferon (IFN)-β (TRIF) signaling pathways downstream of TLRs. Consequently, CD80/86 expression was suppressed by TcpAh via attenuating TLR-stimulated NF-κB activation, which ultimately led to the impairment of the major costimulatory signal essential for the initiation of adaptive humoral immunity against A. hydrophila infection. We believe that this study is the first to show a previously unrecognized mechanism underlying A. hydrophila evades from host antibacterial defense by intervening CD80/86 signal, which bridges innate and adaptive immunity. The mechanism will benefit the development of therapeutic interventions for A. hydrophila infection and septicemia by targeting TcpAh homologs.
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Affiliation(s)
- Huai-Ping Tang
- College of Life Sciences, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, Zhejiang University, Hangzhou, China
| | - Chen Huang
- College of Life Sciences, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, Zhejiang University, Hangzhou, China
| | - Chong-Bin Hu
- College of Life Sciences, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, Zhejiang University, Hangzhou, China
| | - Hao Li
- College of Life Sciences, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, Zhejiang University, Hangzhou, China
| | - Tong Shao
- College of Life Sciences, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, Zhejiang University, Hangzhou, China
| | - Jian-Fei Ji
- College of Life Sciences, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, Zhejiang University, Hangzhou, China
| | - Jun Bai
- College of Life Sciences, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, Zhejiang University, Hangzhou, China
| | - Dong-Dong Fan
- College of Life Sciences, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, Zhejiang University, Hangzhou, China
| | - Ai-Fu Lin
- College of Life Sciences, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, Zhejiang University, Hangzhou, China
| | - Li-Xin Xiang
- College of Life Sciences, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, Zhejiang University, Hangzhou, China
| | - Jian-Zhong Shao
- College of Life Sciences, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, Zhejiang University, Hangzhou, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
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9
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Alaidarous M. In silico structural homology modeling and characterization of multiple N-terminal domains of selected bacterial Tcps. PeerJ 2020; 8:e10143. [PMID: 33194392 PMCID: PMC7646307 DOI: 10.7717/peerj.10143] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 09/19/2020] [Indexed: 11/20/2022] Open
Abstract
Several bacterial pathogens produce Toll/interleukin-1 receptor (TIR) domain-containing protein homologs that are important for subverting the Toll-like receptor (TLR) signaling cascades in hosts. Consequently, promoting the persistence and survival of the bacterial pathogens. However, the exact molecular mechanisms elucidating the functional characteristics of these bacterial proteins are not clear. Physicochemical and homology modeling characterization studies have been conducted to predict the conditions suitable for the stability and purification of these proteins and to predict their structural properties. The outcomes of these studies have provided important preliminary data for the drug discovery pipeline projects. Here, using in silico physicochemical and homology modeling tools, we have reported the primary, secondary and tertiary structural characteristics of multiple N-terminal domains of selected bacterial TIR domain-containing proteins (Tcps). The results show variations between the primary amino acid sequences, secondary structural components and three-dimensional models of the proteins, suggesting the role of different molecular mechanisms in the functioning of these proteins in subverting the host immune system. This study could form the basis of future experimental studies advancing our understanding of the molecular basis of the inhibition of the host immune response by the bacterial Tcps.
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Affiliation(s)
- Mohammed Alaidarous
- Department of Medical Laboratory Sciences, College of Applied Medical Sciences, Majmaah University, Majmaah, Saudi Arabia.,Health and Basic Sciences Research Center, Majmaah University, Majmaah, Saudi Arabia
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10
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Lai JS, Rost B, Kobe B, Bodén M. Evolutionary model of protein secondary structure capable of revealing new biological relationships. Proteins 2020; 88:1251-1259. [PMID: 32394426 DOI: 10.1002/prot.25898] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Revised: 10/24/2019] [Accepted: 04/27/2020] [Indexed: 11/09/2022]
Abstract
Ancestral sequence reconstruction has had recent success in decoding the origins and the determinants of complex protein functions. However, phylogenetic analyses of remote homologues must handle extreme amino acid sequence diversity resulting from extended periods of evolutionary change. We exploited the wealth of protein structures to develop an evolutionary model based on protein secondary structure. The approach follows the differences between discrete secondary structure states observed in modern proteins and those hypothesized in their immediate ancestors. We implemented maximum likelihood-based phylogenetic inference to reconstruct ancestral secondary structure. The predictive accuracy from the use of the evolutionary model surpasses that of comparative modeling and sequence-based prediction; the reconstruction extracts information not available from modern structures or the ancestral sequences alone. Based on a phylogenetic analysis of a sequence-diverse protein family, we showed that the model can highlight relationships that are evolutionarily rooted in structure and not evident in amino acid-based analysis.
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Affiliation(s)
- Jhih-Siang Lai
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Burkhard Rost
- Department of Informatics, Institute of Advanced Studies (TUM-IAS), School of Life Sciences (WZW), Technical University of Munich (TUM), Garching, Bavaria, Germany
| | - Bostjan Kobe
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, Australia.,Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Queensland, Australia.,Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
| | - Mikael Bodén
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, Australia.,Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
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Wolden R, Pain M, Karlsson R, Karlsson A, Aarag Fredheim EG, Cavanagh JP. Identification of surface proteins in a clinical Staphylococcus haemolyticus isolate by bacterial surface shaving. BMC Microbiol 2020; 20:80. [PMID: 32264835 PMCID: PMC7137321 DOI: 10.1186/s12866-020-01778-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 03/31/2020] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND The skin commensal Staphylococcus haemolyticus is an emerging nosocomial pathogen. Despite its clinical relevance, published information about S. haemolyticus virulence factors is scarce. In this study, the adhesive and biofilm forming properties of ten clinical and ten commensal S. haemolyticus strains were examined using standard adhesion and biofilm assays. One of the clinical strains was used to identify expressed surface proteins using bacterial surface shaving. Protein abundance was examined by a comparative analysis between bacterial protein expression after human keratinocyte (HaCaT) colonization and growth in cell culture media supplemented with serum. Relative protein quantification was performed by labeling peptides with tandem mass tags (TMT) prior to Mass Spectrometry analysis. Surface proteins can be used as novel targets for antimicrobial treatment and in diagnostics. RESULTS Adherence to fibronectin, collagen and plastic was low in all tested strains, but with significantly higher adhesion to fibronectin (p = 0.041) and collagen (p = 0.001) in the commensal strains. There was a trend towards higher degree of biofilm formation in the clinical strains (p = 0.059). By using surface shaving, 325 proteins were detected, of which 65 were classified as surface proteins. Analyses showed that the abundance of nineteen (5.8%) proteins were significantly changed following HaCaT colonization. The bacterial Toll/interleukin-1 like (TIRs) domain containing protein (p = 0.04), the transglycosylase SceD (p = 0.01), and the bifunctional autolysin Atl (p = 0.04) showed a 1.4, 1.6- and 1.5-fold increased abundance. The staphylococcal secretory antigen (SsaA) (p = 0.04) was significantly downregulated (- 1.5 fold change) following HaCaT colonization. Among the 65 surface proteins the elastin binding protein (Ebps), LPXAG and LPXSG domain containing proteins and five LPXTG domain containing proteins were identified; three Sdr-like proteins, the extracellular matrix binding protein Embp and a SasH-like protein. CONCLUSIONS This study has provided novel knowledge about expression of S. haemolyticus surface proteins after direct contact with eukaryotic cells and in media supplemented with serum. We have identified surface proteins and immune evasive proteins previously only functionally described in other staphylococcal species. The identification of expressed proteins after host-microbe interaction offers a tool for the discovery and design of novel targets for antimicrobial treatment.
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Affiliation(s)
- Runa Wolden
- Pediatric Research group, Department of Clinical Medicine, Faculty of Health Sciences, UiT The Arctic University of Norway, Tromsø, Norway
| | - Maria Pain
- Pediatric Research group, Department of Clinical Medicine, Faculty of Health Sciences, UiT The Arctic University of Norway, Tromsø, Norway
| | - Roger Karlsson
- Nanoxis Consulting AB, Gothenburg, Sweden
- Department of Infectious Diseases, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
- Department of Clinical Microbiology, Sahlgrenska University Hospital, SE-413 46, Gothenburg, Region Västra Götaland, Sweden
| | | | - Elizabeth G Aarag Fredheim
- Microbial Pharmacology and Population Biology, Department of Pharmacy, Faculty of Health Sciences, UiT The Arctic University of Norway, Tromsø, Norway
| | - Jorunn Pauline Cavanagh
- Pediatric Research group, Department of Clinical Medicine, Faculty of Health Sciences, UiT The Arctic University of Norway, Tromsø, Norway.
- Department of Pediatrics, The University Hospital of North Norway, Tromsø, Norway.
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12
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Liu T, Li L, Wei W, Wang K, Yang Q, Wang E. Yersinia ruckeri strain SC09 disrupts proinflammatory activation via Toll/IL-1 receptor-containing protein STIR-3. FISH & SHELLFISH IMMUNOLOGY 2020; 99:424-434. [PMID: 32087278 DOI: 10.1016/j.fsi.2020.02.035] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 02/11/2020] [Accepted: 02/16/2020] [Indexed: 06/10/2023]
Abstract
Virulent pathogenic microorganisms often enhance their infectivity through immune evasion mechanisms. Our research on the integrative and conjugative element (ICE(r2)) of the virulent fish pathogen Yersinia ruckeri SC09 led to the identification of genes related to immune evasion (designated stir-1, stir-2, stir-3 and stir-4), among which stir-1 and stir-2 were determined as the key contributors to bacterial toxicity and immune evasion. Here, we further examined the ability of stir-3 to mediate immune evasion based on detailed bioinformatic analysis of ICE(r2) from Y. ruckeri SC09. Interactions among the translated STIR-1, STIR-2, STIR-3 and STIR-4 proteins in the secretory process were additionally explored. STIR-3 was positively correlated with bacterial toxicity and inhibited host toll-like receptor (TLR) signaling by interacting with MyD88, thereby facilitating bacterial survival in host cells. Importantly, our data showed co-secretion of STIR-1, STIR-2 and STIR-3 as a complex, with secretion failure occurring in the absence of any one of these proteins. While stir-1, stir-2, stir-3 and stir-4 genes werespecific to Y. ruckeri SC09, the ICE(r2) region where these genes were located is a mobile component widely distributed in bacteria. Therefore, the potential transmission risk of these immune evasion genes requires further research attention.
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Affiliation(s)
- Tao Liu
- Department of Basic Veterinary, Veterinary Medicine College, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Liangyu Li
- Institute of Fisheries of Chengdu Agriculture and Forestry Academy, Chengdu, China
| | - Wenyan Wei
- Institute of Fisheries of Chengdu Agriculture and Forestry Academy, Chengdu, China
| | - Kaiyu Wang
- Department of Basic Veterinary, Veterinary Medicine College, Sichuan Agricultural University, Chengdu, Sichuan, China; Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, China.
| | - Qian Yang
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Erlong Wang
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, China
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13
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Avila-Calderón ED, Flores-Romo L, Sharon W, Donis-Maturano L, Becerril-García MA, Arreola MGA, Reynoso BA, Güemes FS, Contreras-Rodríguez A. Dendritic cells and Brucella spp. interaction: the sentinel host and the stealthy pathogen. Folia Microbiol (Praha) 2020; 65:1-16. [PMID: 30783994 PMCID: PMC7224029 DOI: 10.1007/s12223-019-00691-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 02/06/2019] [Indexed: 01/18/2023]
Abstract
As dendritic cells (DCs) are among the first cells to encounter antigens, these cells trigger both innate and T cell responses, and are the most potent antigen-presenting cells. Brucella spp., which is an intracellular facultative and stealthy pathogen, is able to evade the bactericidal activities of professional phagocytes. Several studies have demonstrated that Brucella can survive and replicate intracellularly, thereby provoking impaired maturation of DCs. Therefore, the interaction between DCs and Brucella becomes an interesting model to study the immune response. In this review, we first will describe the most common techniques for DCs differentiation in vitro as well as general features of brucellosis. Then, the interaction of DCs and Brucella, including pathogen recognition, molecular mechanisms of bacterial pathogenesis, and intracellular trafficking of Brucella to subvert innate response, will be reviewed. Finally, we will debate diversity in immunological DC response and the controversial role of DC activation against Brucella infection.
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Affiliation(s)
- Eric Daniel Avila-Calderón
- Departamento de Biología Celular, Centro de Investigación y de Estudios Avanzados, Instituto Politécnico Nacional, CINVESTAV-IPN, Av. IPN No 2508, Zacatenco, C.P 07330, Mexico city, Mexico
- Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Prolongación de Carpio y Plan de Ayala S/N, Santo Tomás, 11340, Mexico city, Mexico
| | - Leopoldo Flores-Romo
- Departamento de Biología Celular, Centro de Investigación y de Estudios Avanzados, Instituto Politécnico Nacional, CINVESTAV-IPN, Av. IPN No 2508, Zacatenco, C.P 07330, Mexico city, Mexico
| | - Witonsky Sharon
- Center for Molecular Medicine and Infectious Diseases/Center for One Health, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, 24061-0442, USA
- Department of Large Animal Clinical Sciences, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, 24061-0442, USA
| | - Luis Donis-Maturano
- Departamento de Innovación Biomédica, Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Carretera Ensenada-Tijuana 3918, Zona Playitas, 22860, Ensenada, Baja California, Mexico
| | - Miguel Angel Becerril-García
- Departamento de Microbiología, Facultad de Medicina, Universidad Autónoma de Nuevo León, Avenida Francisco I Madero y Dr. Aguirre Pequeño S/N Mitras Centro, 64460, Monterrey, Nuevo León, Mexico
| | - Ma Guadalupe Aguilera Arreola
- Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Prolongación de Carpio y Plan de Ayala S/N, Santo Tomás, 11340, Mexico city, Mexico
| | - Beatriz Arellano Reynoso
- Departamento de Microbiología e Inmunología, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, Coyoacán, 04510, Mexico city, Mexico
| | - Francisco Suarez Güemes
- Departamento de Microbiología e Inmunología, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, Coyoacán, 04510, Mexico city, Mexico
| | - Araceli Contreras-Rodríguez
- Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Prolongación de Carpio y Plan de Ayala S/N, Santo Tomás, 11340, Mexico city, Mexico.
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14
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Toshchakov VY, Neuwald AF. A survey of TIR domain sequence and structure divergence. Immunogenetics 2020; 72:181-203. [PMID: 32002590 PMCID: PMC7075850 DOI: 10.1007/s00251-020-01157-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 01/20/2020] [Indexed: 12/31/2022]
Abstract
Toll-interleukin-1R resistance (TIR) domains are ubiquitously present in all forms of cellular life. They are most commonly found in signaling proteins, as units responsible for signal-dependent formation of protein complexes that enable amplification and spatial propagation of the signal. A less common function of TIR domains is their ability to catalyze nicotinamide adenine dinucleotide degradation. This survey analyzes 26,414 TIR domains, automatically classified based on group-specific sequence patterns presumably determining biological function, using a statistical approach termed Bayesian partitioning with pattern selection (BPPS). We examine these groups and patterns in the light of available structures and biochemical analyses. Proteins within each of thirteen eukaryotic groups (10 metazoans and 3 plants) typically appear to perform similar functions, whereas proteins within each prokaryotic group typically exhibit diverse domain architectures, suggesting divergent functions. Groups are often uniquely characterized by structural fold variations associated with group-specific sequence patterns and by herein identified sequence motifs defining TIR domain functional divergence. For example, BPPS identifies, in helices C and D of TIRAP and MyD88 orthologs, conserved surface-exposed residues apparently responsible for specificity of TIR domain interactions. In addition, BPPS clarifies the functional significance of the previously described Box 2 and Box 3 motifs, each of which is a part of a larger, group-specific block of conserved, intramolecularly interacting residues.
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Affiliation(s)
- Vladimir Y Toshchakov
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA.
| | - Andrew F Neuwald
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
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15
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Piscirickettsia salmonis Cryptic Plasmids: Source of Mobile DNA and Virulence Factors. Pathogens 2019; 8:pathogens8040269. [PMID: 31795181 PMCID: PMC6963756 DOI: 10.3390/pathogens8040269] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 11/18/2019] [Accepted: 11/22/2019] [Indexed: 11/16/2022] Open
Abstract
Four large cryptic plasmids were identified in the salmon pathogen Piscirickettsia salmonis reference strain LF-89. These plasmids appeared highly novel, with less than 7% nucleotidic identity to the nr plasmid database. Plasmid copy number analysis revealed that they are harbored in chromosome equivalent ratios. In addition to plasmid-related genes (plasmidial autonomous replication, partitioning, maintenance, and mobilization genes), mobile genetic elements such as transposases, integrases, and prophage sequences were also identified in P. salmonis plasmids. However, bacterial lysis was not observed upon the induction of prophages. A total of twelve putative virulence factors (VFs) were identified, in addition to two global transcriptional regulators, the widely conserved CsrA protein and the regulator Crp/Fnr. Eleven of the putative VFs were overexpressed during infection in two salmon-derived cellular infection models, supporting their role as VFs. The ubiquity of these plasmids was also confirmed by sequence similarity in the genomes of other P. salmonis strains. The ontology of P. salmonis plasmids suggests a role in bacterial fitness and adaptation to the environment as they encode proteins related to mobilization, nutrient transport and utilization, and bacterial virulence. Further functional characterization of P. salmonis plasmids may improve our knowledge regarding virulence and mobile elements in this intracellular pathogen.
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16
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Liu T, Wang E, Wei W, Wang K, Yang Q, Ai X. TcpA, a novel Yersinia ruckeri TIR-containing virulent protein mediates immune evasion by targeting MyD88 adaptors. FISH & SHELLFISH IMMUNOLOGY 2019; 94:58-65. [PMID: 31470137 DOI: 10.1016/j.fsi.2019.08.069] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 08/24/2019] [Accepted: 08/26/2019] [Indexed: 06/10/2023]
Abstract
TIR domain-containing protein is an important member for some bacterial pathogens to subvert host defenses. Here we described a fish virulent Yersinia ruckeri SC09 strain that interfered directly with Toll-like receptor (TLR) function by a TIR-containing protein. Firstly, the novel TIR-containing protein was identified by bioinformatics analysis and named as TcpA. Secondly, the toxic effects of TcpA in fish was demonstrated in vivo challenge experiments through knockout mutant and complement mutant of tcpA gene. Thirdly, The study in vitro revealed that TcpA could down-regulate the expression and secretion of IL-6, IL-1β and TNF-α. Finally, we demonstrated that TcpA could inhibit the TLR signaling pathway through interaction with myeloid differentiation factor 88 (MyD88) in experiments such as NF-κB dependent luciferase reporter system, co-immunoprecipitation, GST pull-down and yeast two-hybrid. The study revealed that TcpA was essential for virulence and was able to interact with the TIR adaptor protein MyD88 and inhibit the pre-inflammatory signal of immune cells and promote the intracellular survival of pathogenic Yersinia ruckeri SC09 strain. In conclusion, our results showed that TcpA acted as a new virulence factor in Y. ruckeri could suppress innate immune response and increase virulence by inhibiting TLR and MyD88-mediated specific signaling, highlighting a novel strategy for innate immune evasion in bacteria.
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Affiliation(s)
- Tao Liu
- Department of Basic Veterinary, Veterinary Medicine College, Sichuan Agricultural University, Chengdu, Sichuan, PR China
| | - Erlong Wang
- Department of Basic Veterinary, Veterinary Medicine College, Sichuan Agricultural University, Chengdu, Sichuan, PR China
| | - Wenyan Wei
- Institute of Fisheries of Chengdu Agriculture and Forestry Academy, Chengdu, PR China
| | - Kaiyu Wang
- Department of Basic Veterinary, Veterinary Medicine College, Sichuan Agricultural University, Chengdu, Sichuan, PR China; Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, PR China.
| | - Qian Yang
- Department of Basic Veterinary, Veterinary Medicine College, Sichuan Agricultural University, Chengdu, Sichuan, PR China
| | - Xiaohui Ai
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan, Hubei, PR China
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17
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A Yersinia ruckeri TIR Domain-Containing Protein (STIR-2) Mediates Immune Evasion by Targeting the MyD88 Adaptor. Int J Mol Sci 2019; 20:ijms20184409. [PMID: 31500298 PMCID: PMC6769684 DOI: 10.3390/ijms20184409] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 08/07/2019] [Accepted: 09/04/2019] [Indexed: 02/07/2023] Open
Abstract
TIR domain-containing proteins are essential for bacterial pathogens to subvert host defenses. This study describes a fish pathogen, Yersinia ruckeri SC09 strain, with a novel TIR domain-containing protein (STIR-2) that affects Toll-like receptor (TLR) function. STIR-2 was identified in Y. ruckeri by bioinformatics analysis. The toxic effects of this gene on fish were determined by in vivo challenge experiments in knockout mutants and complement mutants of the stir-2 gene. In vitro, STIR-2 downregulated the expression and secretion of IL-6, IL-1β, and TNF-α. Furthermore, the results of NF-κB-dependent luciferase reporter system, co-immunoprecipitation, GST pull-down assays, and yeast two-hybrid assay indicated that STIR-2 inhibited the TLR signaling pathway by interacting with myeloid differentiation factor 88 (MyD88). In addition, STIR-2 promoted the intracellular survival of pathogenic Yersinia ruckeri SC09 strain by binding to the TIR adaptor protein MyD88 and inhibiting the pre-inflammatory signal of immune cells. These results showed that STIR-2 increased virulence in Y. ruckeri and suppressed the innate immune response by inhibiting TLR and MyD88-mediated signaling, serving as a novel strategy for innate immune evasion.
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18
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Enterococcus faecium TIR-Domain Genes Are Part of a Gene Cluster Which Promotes Bacterial Survival in Blood. Int J Microbiol 2019; 2018:1435820. [PMID: 30631364 PMCID: PMC6304867 DOI: 10.1155/2018/1435820] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 10/14/2018] [Indexed: 11/29/2022] Open
Abstract
Enterococcus faecium has undergone a transition to a multidrug-resistant nosocomial pathogen. The population structure of E. faecium is characterized by a sharp distinction of clades, where the hospital-adapted lineage is primarily responsible for bacteremia. So far, factors that were identified in hospital-adapted strains and that promoted pathogenesis of nosocomial E. faecium mainly play a role in adherence and biofilm production, while less is known about factors contributing to survival in blood. This study identified a gene cluster, which includes genes encoding bacterial Toll/interleukin-1 receptor- (TIR-) domain-containing proteins (TirEs). The cluster was found to be unique to nosocomial strains and to be located on a putative mobile genetic element of phage origin. The three genes within the cluster appeared to be expressed as an operon. Expression was detected in bacterial culture media and in the presence of human blood. TirEs are released into the bacterial supernatant, and TirE2 is associated with membrane vesicles. Furthermore, the tirE-gene cluster promotes bacterial proliferation in human blood, indicating that TirE may contribute to the pathogenesis of bacteremia.
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19
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Nanson JD, Kobe B, Ve T. Death, TIR, and RHIM: Self-assembling domains involved in innate immunity and cell-death signaling. J Leukoc Biol 2018; 105:363-375. [PMID: 30517972 DOI: 10.1002/jlb.mr0318-123r] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2018] [Revised: 10/31/2018] [Accepted: 11/01/2018] [Indexed: 12/14/2022] Open
Abstract
The innate immune system consists of pattern recognition receptors (PRRs) that detect pathogen- and endogenous danger-associated molecular patterns (PAMPs and DAMPs), initiating signaling pathways that lead to the induction of cytokine expression, processing of pro-inflammatory cytokines, and induction of cell-death responses. An emerging concept in these pathways and associated processes is signaling by cooperative assembly formation (SCAF), which involves formation of higher order oligomeric complexes, and enables rapid and strongly amplified signaling responses to minute amounts of stimulus. Many of these signalosomes assemble through homotypic interactions of members of the death-fold (DF) superfamily, Toll/IL-1 receptor (TIR) domains, or the RIP homotypic interaction motifs (RHIM). We review the current understanding of the structure and function of these domains and their molecular interactions with a particular focus on higher order assemblies.
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Affiliation(s)
- Jeffrey D Nanson
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience and Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, Queensland, 4072, Australia
| | - Bostjan Kobe
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience and Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, Queensland, 4072, Australia
| | - Thomas Ve
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience and Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, Queensland, 4072, Australia.,Institute for Glycomics, Griffith University, Southport, Queensland, 4222, Australia
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20
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Askarian F, Wagner T, Johannessen M, Nizet V. Staphylococcus aureus modulation of innate immune responses through Toll-like (TLR), (NOD)-like (NLR) and C-type lectin (CLR) receptors. FEMS Microbiol Rev 2018; 42:656-671. [PMID: 29893825 PMCID: PMC6098222 DOI: 10.1093/femsre/fuy025] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 06/07/2018] [Indexed: 02/07/2023] Open
Abstract
Early recognition of pathogens by the innate immune system is crucial for bacterial clearance. Many pattern recognition receptors (PRRs) such as Toll-like (TLRs) and (NOD)-like (NLRs) receptors have been implicated in initial sensing of bacterial components. The intracellular signaling cascades triggered by these receptors result in transcriptional upregulation of inflammatory pathways. Although this step is crucial for bacterial elimination, it is also associated with the potential for substantial immunopathology, which underscores the need for tight control of inflammatory responses. The leading human bacterial pathogen Staphylococcus aureus expresses over 100 virulence factors that exert numerous effects upon host cells. In this manner, the pathogen seeks to avoid host recognition or perturb PRR-induced innate immune responses to allow optimal survival in the host. These immune system interactions may result in enhanced bacterial proliferation but also provoke systemic cytokine responses associated with sepsis. This review summarizes recent findings on the various mechanisms applied by S. aureus to modulate or interfere with inflammatory responses through PRRs. Detailed understanding of these complex interactions can provide new insights toward future immune-stimulatory therapeutics against infection or immunomodulatory therapeutics to suppress or correct dysregulated inflammation.
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Affiliation(s)
- Fatemeh Askarian
- Research Group of Host Microbe Interaction, Faculty of Health Sciences, UiT-The Arctic University of Norway, 9037 Tromsø, Norway
- Division of Host-Microbe Systems & Therapeutics, Department of Pediatrics, UC San Diego, La Jolla, CA 92093, USA
| | - Theresa Wagner
- Research Group of Host Microbe Interaction, Faculty of Health Sciences, UiT-The Arctic University of Norway, 9037 Tromsø, Norway
| | - Mona Johannessen
- Research Group of Host Microbe Interaction, Faculty of Health Sciences, UiT-The Arctic University of Norway, 9037 Tromsø, Norway
| | - Victor Nizet
- Division of Host-Microbe Systems & Therapeutics, Department of Pediatrics, UC San Diego, La Jolla, CA 92093, USA
- Skaggs School of Pharmacy and Pharmaceutical Sciences, UC San Diego, La Jolla, CA 92093, USA
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21
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Abstract
The extracellular forms of the IL-1 cytokines are active through binding to specific receptors on the surface of target cells. IL-1 ligands bind to the extracellular portion of their ligand-binding receptor chain. For signaling to take place, a non-binding accessory chain is recruited into a heterotrimeric complex. The intracellular approximation of the Toll-IL-1-receptor (TIR) domains of the 2 receptor chains is the event that initiates signaling. The family of IL-1 receptors (IL-1R) includes 10 structurally related members, and the distantly related soluble protein IL-18BP that acts as inhibitor of the cytokine IL-18. Over the years the receptors of the IL-1 family have been known with many different names, with significant confusion. Thus, we will use here a recently proposed unifying nomenclature. The family includes several ligand-binding chains (IL-1R1, IL-1R2, IL-1R4, IL-1R5, and IL-1R6), 2 types of accessory chains (IL-1R3, IL-1R7), molecules that act as inhibitors of signaling (IL-1R2, IL-1R8, IL-18BP), and 2 orphan receptors (IL-1R9, IL-1R10). In this review, we will examine how the receptors of the IL-1 family regulate the inflammatory and anti-inflammatory functions of the IL-1 cytokines and are, more at large, involved in modulating defensive and pathological innate immunity and inflammation. Regulation of the IL-1/IL-1R system in the brain will be also described, as an example of the peculiarities of organ-specific modulation of inflammation.
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Affiliation(s)
- Diana Boraschi
- Institute of Protein Biochemistry, National Research Council, Naples, Italy
| | - Paola Italiani
- Institute of Protein Biochemistry, National Research Council, Naples, Italy
| | - Sabrina Weil
- Immunology FB08, Justus-Liebig-Universitat Giessen, Giessen, Germany
| | - Michael U Martin
- Immunology FB08, Justus-Liebig-Universitat Giessen, Giessen, Germany
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22
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TLR4 Signaling Pathway Modulators as Potential Therapeutics in Inflammation and Sepsis. Vaccines (Basel) 2017; 5:vaccines5040034. [PMID: 28976923 PMCID: PMC5748601 DOI: 10.3390/vaccines5040034] [Citation(s) in RCA: 343] [Impact Index Per Article: 49.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 09/29/2017] [Accepted: 10/01/2017] [Indexed: 02/06/2023] Open
Abstract
Toll-Like Receptor 4 (TLR4) signal pathway plays an important role in initiating the innate immune response and its activation by bacterial endotoxin is responsible for chronic and acute inflammatory disorders that are becoming more and more frequent in developed countries. Modulation of the TLR4 pathway is a potential strategy to specifically target these pathologies. Among the diseases caused by TLR4 abnormal activation by bacterial endotoxin, sepsis is the most dangerous one because it is a life-threatening acute system inflammatory condition that still lacks specific pharmacological treatment. Here, we review molecules at a preclinical or clinical phase of development, that are active in inhibiting the TLR4-MyD88 and TLR4-TRIF pathways in animal models. These are low-molecular weight compounds of natural and synthetic origin that can be considered leads for drug development. The results of in vivo studies in the sepsis model and the mechanisms of action of drug leads are presented and critically discussed, evidencing the differences in treatment results from rodents to humans.
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23
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Wang H, Zhou B, Niu R, Wang J, Zhang J, Wang J. Analysis of the roles of dietary protein and calcium in fluoride-induced changes in T-lymphocyte subsets in rat. ENVIRONMENTAL TOXICOLOGY 2017; 32:1587-1595. [PMID: 28158927 DOI: 10.1002/tox.22386] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Revised: 12/05/2016] [Accepted: 12/13/2016] [Indexed: 06/06/2023]
Abstract
The roles of dietary protein (Pr) and calcium (Ca) levels on the changes in T-lymphocyte subsets induced by excessive fluoride (F) intake were assessed using rats that were malnourished for 120 days as a model. The CD4+ and CD8+ T-lymphocytes in the spleen tissue were determined by flow cytometry and immunofluorescence assay. The percentages of CD3+ , CD4+ , and CD8+ T-lymphocytes were reduced in the spleen of rats exposed to excessive F, and malnutrition aggravated these changes in the T-lymphocytes. In addition, the mRNA expression levels of IL-1β, IL-2, IL-6, TNF-α, and IFN-γ in the spleen were downregulated significantly. We also reported herein the increased apoptosis ratio following caspase-9 and caspase-3 upregulation in the spleen of rats exposed to excessive amount of F. Light and transmisison electron microscopy revealed the irregularly arranged lymphocytes, few lymph nodules and the apoptotic characteristic of lymphocytes, which are caused by the increased expression of caspase. In addition, Pr and Ca supplementation reversed the morphologic and T-lymphocytic changes in spleen under malnutrition. Taken together, our results revealed an endogenous caspase-mediated mechanism of regulating the apoptosis of the T-lymphocyte subsets, as well as the immune-related cytokine secretion, which reduces the immune function in F-induced rats. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1587-1595, 2017.
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Affiliation(s)
- Hongwei Wang
- Shanxi Key Laboratory of Ecological Animal Science and Environmental Medicine, Shanxi Agricultural University, Taigu, Shanxi, 030801, People's Republic of China
- College of Animal Science and Technology, Henan University of Science and Technology, Luoyang, Henan, 471003, People's Republic of China
| | - Bianhua Zhou
- Shanxi Key Laboratory of Ecological Animal Science and Environmental Medicine, Shanxi Agricultural University, Taigu, Shanxi, 030801, People's Republic of China
- College of Animal Science and Technology, Henan University of Science and Technology, Luoyang, Henan, 471003, People's Republic of China
| | - Ruiyan Niu
- Shanxi Key Laboratory of Ecological Animal Science and Environmental Medicine, Shanxi Agricultural University, Taigu, Shanxi, 030801, People's Republic of China
| | - Jinming Wang
- Shanxi Key Laboratory of Ecological Animal Science and Environmental Medicine, Shanxi Agricultural University, Taigu, Shanxi, 030801, People's Republic of China
| | - Jianhai Zhang
- Shanxi Key Laboratory of Ecological Animal Science and Environmental Medicine, Shanxi Agricultural University, Taigu, Shanxi, 030801, People's Republic of China
| | - Jundong Wang
- Shanxi Key Laboratory of Ecological Animal Science and Environmental Medicine, Shanxi Agricultural University, Taigu, Shanxi, 030801, People's Republic of China
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24
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Nimma S, Ve T, Williams SJ, Kobe B. Towards the structure of the TIR-domain signalosome. Curr Opin Struct Biol 2017; 43:122-130. [PMID: 28092811 DOI: 10.1016/j.sbi.2016.12.014] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Revised: 12/23/2016] [Accepted: 12/24/2016] [Indexed: 11/17/2022]
Abstract
TIR (Toll/interleukin-1 receptor/resistance protein) domains feature in animal, plant and bacterial proteins involved in innate immunity pathways and associated processes. They function through protein:protein interactions, in particular self-association and homotypic association with other TIR domains. Structures of TIR domains from all phyla have been determined, but common association modes have only emerged for plant and bacterial TIR domains, and not for mammalian TIR domains. Numerous attempts involving hybrid approaches, which have combined structural, computational, mutagenesis and biophysical data, have failed to converge onto common models of how these domains associate and function. We propose that the available data can be reconciled in the context of higher-order assembly formation, and that TIR domains function through signaling by cooperative assembly formation (SCAF).
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Affiliation(s)
- Surekha Nimma
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience and Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD 4072, Australia
| | - Thomas Ve
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience and Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD 4072, Australia; Institute for Glycomics, Griffith University, Southport, QLD 4222, Australia
| | - Simon J Williams
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience and Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD 4072, Australia; Research School of Biology, The Australian National University, Canberra, ACT 2601, Australia
| | - Bostjan Kobe
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience and Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD 4072, Australia.
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The TIR Homologue Lies near Resistance Genes in Staphylococcus aureus, Coupling Modulation of Virulence and Antimicrobial Susceptibility. PLoS Pathog 2017; 13:e1006092. [PMID: 28060920 PMCID: PMC5218399 DOI: 10.1371/journal.ppat.1006092] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 11/28/2016] [Indexed: 01/04/2023] Open
Abstract
Toll/interleukin-1 receptor (TIR) domains in Toll-like receptors are essential for initiating and propagating the eukaryotic innate immune signaling cascade. Here, we investigate TirS, a Staphylococcus aureus TIR mimic that is part of a novel bacterial invasion mechanism. Its ectopic expression in eukaryotic cells inhibited TLR signaling, downregulating the NF-kB pathway through inhibition of TLR2, TLR4, TLR5, and TLR9. Skin lesions induced by the S. aureus knockout tirS mutant increased in a mouse model compared with wild-type and restored strains even though the tirS-mutant and wild-type strains did not differ in bacterial load. TirS also was associated with lower neutrophil and macrophage activity, confirming a central role in virulence attenuation through local inflammatory responses. TirS invariably localizes within the staphylococcal chromosomal cassettes (SCC) containing the fusC gene for fusidic acid resistance but not always carrying the mecA gene. Of note, sub-inhibitory concentration of fusidic acid increased tirS expression. Epidemiological studies identified no link between this effector and clinical presentation but showed a selective advantage with a SCCmec element with SCC fusC/tirS. Thus, two key traits determining the success and spread of bacterial infections are linked. Pathogenic microbes have evolved elaborate strategies to manipulate host defenses to establish and spread in the host population. One such mechanism involves disruption of the immune signaling cascade orchestrated by the Toll-like receptors (TLRs), which sense microbial attack. TLR signaling elicits a proinflammatory response that controls immune cell recruitment to infected tissues. Here, we show that Staphylococcus aureus, an opportunistic human pathogen, expresses a host defense–like protein, TirS, that actively perturbs the initial TLR activation stage. Results with isolated human cells and mouse models show that TirS is a broad innate immune inhibitor of TLR-dependent signaling and modulates bacterial virulence, attenuating local inflammation. Moreover, the tirS gene lies near antimicrobial resistance genes for an antibiotic that enhances TirS production, shifting the balance to favor the pathogen and promote disease. Understanding mechanisms by which S. aureus modulates the immune response may lead to novel approaches for preventing and treating infection.
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Carlsson E, Thwaite JE, Jenner DC, Spear AM, Flick-Smith H, Atkins HS, Byrne B, Ding JL. Bacillus anthracis TIR Domain-Containing Protein Localises to Cellular Microtubule Structures and Induces Autophagy. PLoS One 2016; 11:e0158575. [PMID: 27391310 PMCID: PMC4938393 DOI: 10.1371/journal.pone.0158575] [Citation(s) in RCA: 2] [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: 04/04/2016] [Accepted: 06/17/2016] [Indexed: 02/06/2023] Open
Abstract
Toll-like receptors (TLRs) recognise invading pathogens and mediate downstream immune signalling via Toll/IL-1 receptor (TIR) domains. TIR domain proteins (Tdps) have been identified in multiple pathogenic bacteria and have recently been implicated as negative regulators of host innate immune activation. A Tdp has been identified in Bacillus anthracis, the causative agent of anthrax. Here we present the first study of this protein, designated BaTdp. Recombinantly expressed and purified BaTdp TIR domain interacted with several human TIR domains, including that of the key TLR adaptor MyD88, although BaTdp expression in cultured HEK293 cells had no effect on TLR4- or TLR2- mediated immune activation. During expression in mammalian cells, BaTdp localised to microtubular networks and caused an increase in lipidated cytosolic microtubule-associated protein 1A/1B-light chain 3 (LC3), indicative of autophagosome formation. In vivo intra-nasal infection experiments in mice showed that a BaTdp knockout strain colonised host tissue faster with higher bacterial load within 4 days post-infection compared to the wild type B. anthracis. Taken together, these findings indicate that BaTdp does not play an immune suppressive role, but rather, its absence increases virulence. BaTdp present in wild type B. anthracis plausibly interact with the infected host cell, which undergoes autophagy in self-defence.
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Affiliation(s)
- Emil Carlsson
- Department of Life Sciences, Imperial College London, London, United Kingdom
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore
| | - Joanne E. Thwaite
- Defence Science and Technology Laboratory, Porton Down, Salisbury, United Kingdom
| | - Dominic C. Jenner
- Defence Science and Technology Laboratory, Porton Down, Salisbury, United Kingdom
| | - Abigail M. Spear
- Defence Science and Technology Laboratory, Porton Down, Salisbury, United Kingdom
| | - Helen Flick-Smith
- Defence Science and Technology Laboratory, Porton Down, Salisbury, United Kingdom
| | - Helen S. Atkins
- Defence Science and Technology Laboratory, Porton Down, Salisbury, United Kingdom
| | - Bernadette Byrne
- Department of Life Sciences, Imperial College London, London, United Kingdom
- * E-mail: (JLD); (BB)
| | - Jeak Ling Ding
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore
- * E-mail: (JLD); (BB)
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27
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Brucella TIR-like protein TcpB/Btp1 specifically targets the host adaptor protein MAL/TIRAP to promote infection. Biochem Biophys Res Commun 2016; 477:509-14. [PMID: 27311859 DOI: 10.1016/j.bbrc.2016.06.064] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 06/13/2016] [Indexed: 02/06/2023]
Abstract
Brucella spp. are known to avoid host immune recognition and weaken the immune response to infection. Brucella like accomplish this by employing two clever strategies, called the stealth strategy and hijacking strategy. The TIR domain-containing protein (TcpB/Btp1) of Brucella melitensis is thought to be involved in inhibiting host NF-κB activation by binding to adaptors downstream of Toll-like receptors. However, of the five TIR domain-containing adaptors conserved in mammals, whether MyD88 or MAL, even other three adaptors, are specifically targeted by TcpB has not been identified. Here, we confirmed the effect of TcpB on B.melitensis virulence in mice and found that TcpB selectively targets MAL. By using siRNA against MAL, we found that TcpB from B.melitensis is involved in intracellular survival and that MAL affects intracellular replication of B.melitensis. Our results confirm that TcpB specifically targets MAL/TIRAP to disrupt downstream signaling pathways and promote intra-host survival of Brucella spp.
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Ke Y, Li W, Wang Y, Yang M, Guo J, Zhan S, Du X, Wang Z, Yang M, Li J, Li W, Chen Z. Inhibition of TLR4 signaling by Brucella TIR-containing protein TcpB-derived decoy peptides. Int J Med Microbiol 2016; 306:391-400. [PMID: 27289452 DOI: 10.1016/j.ijmm.2016.05.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Revised: 05/04/2016] [Accepted: 05/08/2016] [Indexed: 02/06/2023] Open
Abstract
Brucella spp. avoid host immune recognition and thus, weaken the immune response to infection. The Toll/interleukin-1 receptor (TIR) domain-containing protein (TcpB/Btp1) of Brucella spp. is thought to be involved in blocking host innate immune responses by binding to adaptors downstream of Toll-like receptors. In this study, based on the observation that TcpB binds to the host target proteins, MAL, through the TIR domain, we examined decoy peptides from TcpB TIR domains and found that TB-8 and TB-9 substantially inhibit lipopolysaccharide (LPS)-induced signaling in vitro and in vivo. Both these peptides share a common loop, the DD loop, indicating a novel structural region mediating TIR interactions. The inhibition of LPS signaling by TB-8 and TB-9 shows no preference to MyD88-dependent cytokines, such as TNF-α and IL-1β or TRIF-dependent cytokines including IFN-β and IL-6. Furthermore, these two peptides rescue the virulence of Brucella ΔtcpB mutants at the cellular level, indicating key roles of the DD loop in Brucella pathogenesis. In conclusion, identification of inhibitors from the bacterial TIR domains is helpful not only for illustrating interacting mechanisms between TIR domains and bacterial pathogenesis, but also for developing novel signaling inhibitors and therapeutics for human inflammatory diseases.
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Affiliation(s)
- Yuehua Ke
- Institute of Disease Control and Prevention, AMMS, Beijing 100071, People's Republic of China
| | - Wenna Li
- Institute of Disease Control and Prevention, AMMS, Beijing 100071, People's Republic of China; School of Public Health, Jilin University, Changchun 130021, People's Republic of China
| | - Yufei Wang
- General Hospital of People's Armed Police Forces, Beijing 100039, People's Republic of China
| | - Mingjuan Yang
- Institute of Disease Control and Prevention, AMMS, Beijing 100071, People's Republic of China
| | - Jinpeng Guo
- Institute of Disease Control and Prevention, AMMS, Beijing 100071, People's Republic of China
| | - Shaoxia Zhan
- Institute of Disease Control and Prevention, AMMS, Beijing 100071, People's Republic of China
| | - Xinying Du
- Institute of Disease Control and Prevention, AMMS, Beijing 100071, People's Republic of China
| | - Zhoujia Wang
- Institute of Disease Control and Prevention, AMMS, Beijing 100071, People's Republic of China
| | - Min Yang
- Construction Engineering Research Institute, Xi'an 71000, Shanxi Province, People's Republic of China
| | - Juan Li
- School of Public Health, Jilin University, Changchun 130021, People's Republic of China.
| | - Wenfeng Li
- Department of Orthopedics, The First Affiliated Hospital of General Hospital of People's Liberation Army, Beijing 100048, People's Republic of China.
| | - Zeliang Chen
- Institute of Disease Control and Prevention, AMMS, Beijing 100071, People's Republic of China; College of Medicine, Shihezi University, Shihezi, People's Republic of China; Research Center of Molecular Biology, Inner Mongolia Medical University, Hohhot, People's Republic of China.
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29
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A Comparative Analysis of the Mechanism of Toll-Like Receptor-Disruption by TIR-Containing Protein C from Uropathogenic Escherichia coli. Pathogens 2016; 5:pathogens5010025. [PMID: 26938564 PMCID: PMC4810146 DOI: 10.3390/pathogens5010025] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 02/23/2016] [Accepted: 02/25/2016] [Indexed: 11/17/2022] Open
Abstract
The TIR-containing protein C (TcpC) of uropathogenic Escherichia coli strains is a powerful virulence factor by impairing the signaling cascade of Toll-like receptors (TLRs). Several other bacterial pathogens like Salmonella, Yersinia, Staphylococcus aureus but also non-pathogens express similar proteins. We discuss here the pathogenic potential of TcpC and its interaction with TLRs and TLR-adapter proteins on the molecular level and compare its activity with the activity of other bacterial TIR-containing proteins. Finally, we analyze and compare the structure of bacterial TIR-domains with the TIR-domains of TLRs and TLR-adapters.
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30
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Carlsson E, Ding JL, Byrne B. SARM modulates MyD88-mediated TLR activation through BB-loop dependent TIR-TIR interactions. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1863:244-53. [PMID: 26592460 DOI: 10.1016/j.bbamcr.2015.11.021] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Revised: 11/16/2015] [Accepted: 11/20/2015] [Indexed: 12/21/2022]
Abstract
Toll-like receptors (TLRs) recognise invading pathogens and initiate an innate immune response by recruiting intracellular adaptor proteins via heterotypic Toll/interleukin-1 receptor (TIR) domain interactions. Of the five TIR domain-containing adaptor proteins identified, Sterile α- and armadillo-motif-containing protein (SARM) is functionally unique; suppressing immune signalling instead of promoting it. Here we demonstrate that the recombinantly expressed and purified SARM TIR domain interacts with both the major human TLR adaptors, MyD88 and TRIF. A single glycine residue located in the BB-loop of the SARM TIR domain, G601, was identified as essential for interaction. A short peptide derived from this motif was also found to interact with MyD88 in vitro. SARM expression in HEK293 cells was found to significantly suppress lipopolysaccharide (LPS)-mediated upregulation of inflammatory cytokines, IL-8 and TNF-α, an effect lost in the G601A mutant. The same result was observed with cytokine activation initiated by MyD88 expression and stimulation of TLR2 with lipoteichoic acid (LTA), suggesting that SARM is capable of suppressing both TRIF- and MyD88- dependent TLR signalling. Our findings indicate that SARM acts on a broader set of target proteins than previously thought, and that the BB-loop motif is functionally important, giving further insight into the endogenous mechanisms used to suppress inflammation in immune cells.
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Affiliation(s)
- Emil Carlsson
- Department of Life Sciences, Imperial College London, SW7 2AZ, UK; Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore 117543, Singapore.
| | - Jeak Ling Ding
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore 117543, Singapore.
| | - Bernadette Byrne
- Department of Life Sciences, Imperial College London, SW7 2AZ, UK.
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31
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Ke Y, Wang Y, Li W, Chen Z. Type IV secretion system of Brucella spp. and its effectors. Front Cell Infect Microbiol 2015; 5:72. [PMID: 26528442 PMCID: PMC4602199 DOI: 10.3389/fcimb.2015.00072] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2015] [Accepted: 09/28/2015] [Indexed: 11/13/2022] Open
Abstract
Brucella spp. are intracellular bacterial pathogens that cause infection in domestic and wild animals. They are often used as model organisms to study intracellular bacterial infections. Brucella VirB T4SS is a key virulence factor that plays important roles in mediating intracellular survival and manipulating host immune response to infection. In this review, we discuss the roles of Brucella VirB T4SS and 15 effectors that are proposed to be crucial for Brucella pathogenesis. VirB T4SS regulates the inflammation response and manipulates vesicle trafficking inside host cells. VirB T4SS also plays crucial roles in the inhibition of the host immune response and intracellular survival during infection. Here, we list the key molecular events in the intracellular life cycle of Brucella that are potentially targeted by the VirB T4SS effectors. Elucidating the functions of these effectors will help clarify the molecular role of T4SS during infection. Furthermore, studying the effectors secreted by Brucella spp. might provide insights into the mechanisms used by the bacteria to hijack the host signaling pathways and aid in the development of better vaccines and therapies against brucellosis.
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Affiliation(s)
- Yuehua Ke
- Institute of Disease Control and Prevention, AMMS Beijing, China
| | - Yufei Wang
- Department of Laboratory Medicine, General Hospital of Chinese People's Armed Police Forces Beijing, China
| | - Wengfeng Li
- Department of Orthopedics, The First Affiliated Hospital of General Hospital of People's Liberation Army Beijing, China
| | - Zeliang Chen
- Institute of Disease Control and Prevention, AMMS Beijing, China
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32
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Sellge G, Kufer TA. PRR-signaling pathways: Learning from microbial tactics. Semin Immunol 2015; 27:75-84. [PMID: 25911384 DOI: 10.1016/j.smim.2015.03.009] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2014] [Accepted: 03/13/2015] [Indexed: 12/13/2022]
Abstract
Recognition of bacterial pathogens by the mammalian host relies on the induction of early innate immune responses initiated by the activation of pattern-recognition receptors (PRRs) upon sensing of their cognate microbe-associated-patterns (MAMPs). Successful pathogens have evolved to intercept PRR activation and signaling at multiple steps. The molecular dissection of the underlying mechanisms revealed many of the basic mechanisms used by the immune system. Here we provide an overview of the different strategies used by bacterial pathogens and commensals to subvert and reprogram PPR-mediated innate immune responses. A particular attention is given to recent discoveries highlighting novel molecular details of the host inflammatory response in mammalian cells and current advances in our understanding of the interaction of commensals with PRR-mediated responses.
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Affiliation(s)
- Gernot Sellge
- Department of Medicine III, University Hospital Aachen, Pauwelsstraße 30, 52074 Aachen, Germany
| | - Thomas A Kufer
- Institute of Nutritional Medicine, Department of Immunology, University of Hohenheim, Fruwirthstr. 12, 70599 Stuttgart, Germany.
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33
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Swarts DC, Makarova K, Wang Y, Nakanishi K, Ketting RF, Koonin EV, Patel DJ, van der Oost J. The evolutionary journey of Argonaute proteins. Nat Struct Mol Biol 2014; 21:743-53. [PMID: 25192263 DOI: 10.1038/nsmb.2879] [Citation(s) in RCA: 320] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Accepted: 07/30/2014] [Indexed: 02/07/2023]
Abstract
Argonaute proteins are conserved throughout all domains of life. Recently characterized prokaryotic Argonaute proteins (pAgos) participate in host defense by DNA interference, whereas eukaryotic Argonaute proteins (eAgos) control a wide range of processes by RNA interference. Here we review molecular mechanisms of guide and target binding by Argonaute proteins, and describe how the conformational changes induced by target binding lead to target cleavage. On the basis of structural comparisons and phylogenetic analyses of pAgos and eAgos, we reconstruct the evolutionary journey of the Argonaute proteins through the three domains of life and discuss how different structural features of pAgos and eAgos relate to their distinct physiological roles.
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Affiliation(s)
- Daan C Swarts
- Laboratory of Microbiology, Department of Agrotechnology and Food Sciences, Wageningen University, Wageningen, the Netherlands
| | - Kira Makarova
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland, USA
| | - Yanli Wang
- Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Kotaro Nakanishi
- Department of Chemistry and Biochemistry, Ohio State University, Columbus, Ohio, USA
| | | | - Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland, USA
| | - Dinshaw J Patel
- Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, USA
| | - John van der Oost
- Laboratory of Microbiology, Department of Agrotechnology and Food Sciences, Wageningen University, Wageningen, the Netherlands
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34
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Felix C, Kaplan Türköz B, Ranaldi S, Koelblen T, Terradot L, O'Callaghan D, Vergunst AC. The Brucella TIR domain containing proteins BtpA and BtpB have a structural WxxxE motif important for protection against microtubule depolymerisation. Cell Commun Signal 2014; 12:53. [PMID: 25304327 PMCID: PMC4203976 DOI: 10.1186/s12964-014-0053-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Accepted: 08/27/2014] [Indexed: 01/12/2023] Open
Abstract
Background The TIR domain-containing proteins BtpA/Btp1/TcpB and BtpB are translocated into host cells by the facultative intracellular bacterial pathogen Brucella. Here, they interfere with Toll like receptor signalling to temper the host inflammatory response. BtpA has also been found to modulate microtubule dynamics. In both proteins we identified a WxxxE motif, previously shown to be an essential structural component in a family of bacterial type III secretion system effectors that modulate host actin dynamics by functioning as guanine nucleotide exchange factors of host GTPases. We analysed a role for the WxxxE motif in association of BtpA and BtpB with the cytoskeleton. Results Unlike BtpA, ectopically expressed BtpB did not show a tubular localisation, but was found ubiquitously in the cytoplasm and the nucleus, and often appeared in discrete punctae in HeLa cells. BtpB was able to protect microtubules from drug-induced destabilisation similar to BtpA. The WxxxE motif was important for the ability of BtpA and BtpB to protect microtubules against destabilising drugs. Surprisingly, ectopic expression of BtpA, although not BtpB, in HeLa cells induced the formation of filopodia. This process was invariably dependent of the WxxxE motif. Our recent resolution of the crystal structure of the BtpA TIR domain reveals that the motif positions a glycine residue that has previously been shown to be essential for interaction of BtpA with microtubules. Conclusions Our results suggest a structural role for the WxxxE motif in the association of BtpA and BtpB with microtubules, as with the WxxxE GEF family proteins where the motif positions an adjacent catalytic loop important for interaction with specific Rho GTPases. In addition, the ability of ectopically expressed BtpA to induce filopodia in a WxxxE-dependent manner suggests a novel property for BtpA. A conserved WxxxE motif is found in most bacterial and several eukaryotic TIR domain proteins. Despite the similarity between ectopically expressed BtpA and WxxxE GEFs to modulate host actin dynamics, our results suggest that BtpA is not part of this WxxxE GEF family. The WxxxE motif may therefore be a more common structural motif than thus far described. BtpA may provide clues to cross-talk between the TLR and GTPase signalling pathways. Electronic supplementary material The online version of this article (doi:10.1186/s12964-014-0053-y) contains supplementary material, which is available to authorized users.
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35
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Pushie MJ, Pickering I, Korbas M, Hackett MJ, George GN. Elemental and chemically specific X-ray fluorescence imaging of biological systems. Chem Rev 2014; 114:8499-541. [PMID: 25102317 PMCID: PMC4160287 DOI: 10.1021/cr4007297] [Citation(s) in RCA: 174] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2013] [Indexed: 12/13/2022]
Affiliation(s)
- M. Jake Pushie
- Molecular
and Environmental Sciences Research Group, Department of Geological
Sciences, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada
| | - Ingrid
J. Pickering
- Molecular
and Environmental Sciences Research Group, Department of Geological
Sciences, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada
- Toxicology
Centre, University of Saskatchewan, Saskatoon, SK S7N 5B3, Canada
- Department
of Chemistry, University of Saskatchewan, Saskatoon, SK S7N 5C9, Canada
| | - Malgorzata Korbas
- Canadian
Light Source Inc., 44
Innovation Boulevard, Saskatoon, SK S7N 2V3, Canada
- Department
of Anatomy and Cell Biology, University
of Saskatchewan, Saskatoon, SK S7N 5E5, Canada
| | - Mark J. Hackett
- Molecular
and Environmental Sciences Research Group, Department of Geological
Sciences, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada
| | - Graham N. George
- Molecular
and Environmental Sciences Research Group, Department of Geological
Sciences, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada
- Toxicology
Centre, University of Saskatchewan, Saskatoon, SK S7N 5B3, Canada
- Department
of Chemistry, University of Saskatchewan, Saskatoon, SK S7N 5C9, Canada
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36
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Askarian F, van Sorge NM, Sangvik M, Beasley FC, Henriksen JR, Sollid JUE, van Strijp JAG, Nizet V, Johannessen M. A Staphylococcus aureus TIR domain protein virulence factor blocks TLR2-mediated NF-κB signaling. J Innate Immun 2014; 6:485-98. [PMID: 24481289 DOI: 10.1159/000357618] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Accepted: 11/25/2013] [Indexed: 01/05/2023] Open
Abstract
Signaling through Toll-like receptors (TLRs), crucial molecules in the induction of host defense responses, requires adaptor proteins that contain a Toll/interleukin-1 receptor (TIR) domain. The pathogen Staphylococcus aureus produces several innate immune-evasion molecules that interfere with the host's innate immune response. A database search analysis suggested the presence of a gene encoding a homologue of the human TIR domain in S. aureus MSSA476 which was named staphylococcal TIR domain protein (TirS). Ectopic expression of TirS in human embryonic kidney, macrophage and keratinocyte cell lines interfered with signaling through TLR2, including MyD88 and TIRAP, NF-κB and/or mitogen-activated protein kinase pathways. Moreover, the presence of TirS reduced the levels of cytokines MCP-1 and G-CSF secreted in response to S. aureus. The effects on NF-κB pathway were confirmed using S. aureus MSSA476 wild type, an isogenic mutant MSSA476ΔtirS, and complemented MSSA476ΔtirS +pTirS in a Transwell system where bacteria and host cells were physically separated. Finally, in a systematic mouse infection model, TirS promoted bacterial accumulation in several organs 4 days postinfection. The results of this study reveal a new S. aureus virulence factor that can interfere with PAMP-induced innate immune signaling in vitro and bacterial survival in vivo.
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Affiliation(s)
- Fatemeh Askarian
- Research Group of Host-Microbe Interactions, Department of Medical Biology, Faculty of Health Sciences, UiT The Artic University of Norway, Tromsø, Norway
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Alaidarous M, Ve T, Casey LW, Valkov E, Ericsson DJ, Ullah MO, Schembri MA, Mansell A, Sweet MJ, Kobe B. Mechanism of bacterial interference with TLR4 signaling by Brucella Toll/interleukin-1 receptor domain-containing protein TcpB. J Biol Chem 2013; 289:654-68. [PMID: 24265315 DOI: 10.1074/jbc.m113.523274] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Upon activation of Toll-like receptors (TLRs), cytoplasmic Toll/interleukin-1 receptor (TIR) domains of the receptors undergo homo- or heterodimerization. This in turn leads to the recruitment of adaptor proteins, activation of transcription factors, and the secretion of pro-inflammatory cytokines. Recent studies have described the TIR domain-containing protein from Brucella melitensis, TcpB (BtpA/Btp1), to be involved in virulence and suppression of host innate immune responses. TcpB interferes with TLR4 and TLR2 signaling pathways by a mechanism that remains controversial. In this study, we show using co-immunoprecipitation analyses that TcpB interacts with MAL, MyD88, and TLR4 but interferes only with the MAL-TLR4 interaction. We present the crystal structure of the TcpB TIR domain, which reveals significant structural differences in the loop regions compared with other TIR domain structures. We demonstrate that TcpB forms a dimer in solution, and the crystal structure reveals the dimerization interface, which we validate by mutagenesis and biophysical studies. Our study advances the understanding of the molecular mechanisms of host immunosuppression by bacterial pathogens.
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Alaidarous M, Ve T, Ullah MO, Valkov E, Mansell A, Schembri MA, Sweet MJ, Kobe B. Cloning, expression, purification, crystallization and preliminary X-ray crystallographic analysis of the TIR domain from the Brucella melitensis TIR-domain-containing protein TcpB. Acta Crystallogr Sect F Struct Biol Cryst Commun 2013; 69:1167-70. [PMID: 24100574 PMCID: PMC3792682 DOI: 10.1107/s1744309113024408] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Accepted: 09/02/2013] [Indexed: 01/23/2023]
Abstract
In mammals, Toll-like receptors (TLRs) recognize conserved microbial molecular signatures and induce an early innate immune response in the host. TLR signalling is mediated by interactions between the cytosolic TIR (Toll/interleukin-1 receptor) domains of the receptor and the adaptor proteins. Increasingly, it is apparent that pathogens target this interaction via pathogen-expressed TIR-domain-containing proteins to modulate immune responses. A TIR-domain-containing protein TcpB has been reported in the pathogenic bacterium Brucella melitensis. Studies have shown that TcpB interferes with the TLR2 and TLR4 signalling pathways to inhibit TLR-mediated inflammatory responses. Such interference may involve TIR-TIR-domain interactions between bacterial and mammalian proteins, but there is a lack of information about these interactions at the molecular level. In this study, the cloning, expression, purification, crystallization and preliminary X-ray crystallographic analysis of the protein construct corresponding to the TIR domain of TcpB (residues 120-250) are reported. The crystals diffracted to 2.6 Å resolution, have the symmetry of the monoclinic space group P2₁ and are most likely to contain four molecules in the asymmetric unit. The structure should help in understanding the molecular basis of how TcpB affects the innate immunity of the host.
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Affiliation(s)
- Mohammed Alaidarous
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, QLD 4072, Australia
- Institute for Molecular Bioscience, University of Queensland, Brisbane, QLD 4072, Australia
- Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD 4072, Australia
| | - Thomas Ve
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, QLD 4072, Australia
- Institute for Molecular Bioscience, University of Queensland, Brisbane, QLD 4072, Australia
- Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD 4072, Australia
| | - M. Obayed Ullah
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, QLD 4072, Australia
- Institute for Molecular Bioscience, University of Queensland, Brisbane, QLD 4072, Australia
- Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD 4072, Australia
| | - Eugene Valkov
- MRC Laboratory of Molecular Biology, Cambridge, CB2 0QH, England
| | - Ashley Mansell
- Centre for Innate Immunity and Infectious Diseases, Monash Institute of Medical Research, Monash University, Melbourne, VIC 3168, Australia
| | - Mark A. Schembri
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, QLD 4072, Australia
- Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD 4072, Australia
| | - Matthew J. Sweet
- Institute for Molecular Bioscience, University of Queensland, Brisbane, QLD 4072, Australia
- Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD 4072, Australia
| | - Bostjan Kobe
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, QLD 4072, Australia
- Institute for Molecular Bioscience, University of Queensland, Brisbane, QLD 4072, Australia
- Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD 4072, Australia
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Kaplan-Türköz B, Koelblen T, Felix C, Candusso MP, O'Callaghan D, Vergunst AC, Terradot L. Structure of the Toll/interleukin 1 receptor (TIR) domain of the immunosuppressive Brucella effector BtpA/Btp1/TcpB. FEBS Lett 2013; 587:3412-6. [PMID: 24076024 DOI: 10.1016/j.febslet.2013.09.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 08/30/2013] [Accepted: 09/03/2013] [Indexed: 11/15/2022]
Abstract
BtpA/Btp1/TcpB is a virulence factor produced by Brucella species that possesses a Toll interleukin-1 receptor (TIR) domain. Once delivered into the host cell, BtpA interacts with MyD88 to interfere with TLR signalling and modulates microtubule dynamics. Here the crystal structure of the BtpA TIR domain at 3.15 Å is presented. The structure shows a dimeric arrangement of a canonical TIR domain, similar to the Paracoccus denitrificans Tir protein but secured by a unique long N-terminal α-tail that packs against the TIR:TIR dimer. Structure-based mutations and multi-angle light scattering experiments characterized the BtpA dimer conformation in solution. The structure of BtpA will help with studies to understand the mechanisms involved in its interactions with MyD88 and with microtubules.
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Affiliation(s)
- Burcu Kaplan-Türköz
- UMR 5086, BMSSI, CNRS - Université Lyon 1, Institut de Biologie et Chimie des Protéines, 7 passage du Vercors, F-69367, France
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41
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Nörenberg D, Wieser A, Magistro G, Hoffmann C, Meyer C, Messerer M, Schubert S. Molecular analysis of a novel Toll/interleukin-1 receptor (TIR)-domain containing virulence protein of Y. pseudotuberculosis among Far East scarlet-like fever serotype I strains. Int J Med Microbiol 2013; 303:583-94. [PMID: 24018301 DOI: 10.1016/j.ijmm.2013.08.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Revised: 07/29/2013] [Accepted: 08/07/2013] [Indexed: 01/05/2023] Open
Abstract
Pathogenicity of Yersinia pseudotuberculosis is determined by an arsenal of virulence factors. Particularly, the Yersinia outer proteins (Yops) and the Type III secretion system (T3SS) encoded on the pYV virulence plasmid are required for Yersinia pathogenicity. A specific group of Y. pseudotuberculosis, responsible for the clinical syndrome described as Far East scarlet-like fever (FESLF), is known to have an altered virulence gene cluster. Far East strains cause unique clinical symptoms for which the pYV virulence plasmid plays apparently a rather secondary role. Here, we characterize a previously unknown protein of Y. pseudotuberculosis serotype I strains (TcpYI) which can be found particularly among the FESLF strain group. The TcpYI protein shares considerable sequence homology to members of the Toll/IL-1 receptor family. Bacterial TIR domain containing proteins (Tcps) interact with the innate immune system by TIR-TIR interactions and subvert host defenses via individual, multifaceted mechanisms. In terms of virulence, it appears that the TcpYI protein of Y. pseudotuberculosis displays its own virulence phenotype compared to the previously characterized bacterial Tcps. Our results clearly demonstrate that TcpYI increases the intracellular survival of the respective strains in vitro. Furthermore, we show here that the intracellular survival benefit of the wild-type strain correlates with an increase in tcpYI gene expression inside murine macrophages. In support of this, we found that TcpYI enhances the survival inside the spleens of mice in a mouse model of peritonitis. Our results may point toward involvement of the TcpYI protein in inhibition of phagocytosis, particularly in distinct Y. pseudotuberculosis strains of the FESLF strain group where the pYV virulence plasmid is absent.
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Affiliation(s)
- Dominik Nörenberg
- Max von Pettenkofer-Institut für Hygiene und Medizinische Mikrobiologie, Marchioninistr. 17, D-81377 München, Germany
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42
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Salcedo SP, Marchesini MI, Degos C, Terwagne M, Von Bargen K, Lepidi H, Herrmann CK, Santos Lacerda TL, Imbert PRC, Pierre P, Alexopoulou L, Letesson JJ, Comerci DJ, Gorvel JP. BtpB, a novel Brucella TIR-containing effector protein with immune modulatory functions. Front Cell Infect Microbiol 2013; 3:28. [PMID: 23847770 PMCID: PMC3703528 DOI: 10.3389/fcimb.2013.00028] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Accepted: 06/18/2013] [Indexed: 12/29/2022] Open
Abstract
Several bacterial pathogens have TIR domain-containing proteins that contribute to their pathogenesis. We identified a second TIR-containing protein in Brucella spp. that we have designated BtpB. We show it is a potent inhibitor of TLR signaling, probably via MyD88. BtpB is a novel Brucella effector that is translocated into host cells and interferes with activation of dendritic cells. In vivo mouse studies revealed that BtpB is contributing to virulence and control of local inflammatory responses with relevance in the establishment of chronic brucellosis. Together, our results show that BtpB is a novel Brucella effector that plays a major role in the modulation of host innate immune response during infection.
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Affiliation(s)
- Suzana P Salcedo
- Aix-Marseille Univ UM 2, Centre d'Immunologie de Marseille-Luminy Marseille, France
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