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Rudolph MJ, Chen Y, Vorauer C, Vance DJ, Piazza CL, Willsey GG, McCarthy K, Muriuki B, Cavacini LA, Guttman M, Mantis NJ. Structure of a human monoclonal antibody in complex with Outer surface protein C (OspC) of the Lyme disease spirochete, Borreliella burgdorferi. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.29.591597. [PMID: 38746285 PMCID: PMC11092446 DOI: 10.1101/2024.04.29.591597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
Lyme disease is a tick-borne, multisystem infection caused by the spirochete, Borreliella burgdorferi . Although antibodies have been implicated in the resolution of Lyme disease, the specific B cell epitopes targeted during human infections remain largely unknown. In this study, we characterized and defined the structural epitope of a patient-derived bactericidal monoclonal IgG ("B11") against Outer surface protein C (OspC), a homodimeric lipoprotein necessary for B. burgdorferi tick-mediated transmission and early-stage colonization of vertebrate hosts. High-resolution epitope mapping was accomplished through hydrogen deuterium exchange-mass spectrometry (HDX-MS) and X-ray crystallography. Structural analysis of B11 Fab-OspC A complexes revealed the B11 Fabs associated in a 1:1 stoichiometry with the lateral faces of OspC A homodimers such that the antibodies are essentially positioned perpendicular to the spirochete's outer surface. B11's primary contacts reside within the membrane proximal regions of α-helices 1 and 6 and adjacent loops 5 and 6 in one OspC A monomer. In addition, B11 spans the OspC A dimer interface, engaging opposing α-helix 1', α-helix 2', and loop 2-3' in the second OspC A monomer. The B11-OspC A structure is reminiscent of the recently solved mouse transmission blocking monoclonal IgG B5 in complex with OspC A , indicating a mode of engagement with OspC that is conserved across species. In conclusion, we provide the first detailed insight into the interaction between a functional human antibody and an immunodominant Lyme disease antigen long considered an important vaccine target.
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Cooperative regulation of PBI1 and MAPKs controls WRKY45 transcription factor in rice immunity. Nat Commun 2022; 13:2397. [PMID: 35577789 PMCID: PMC9110426 DOI: 10.1038/s41467-022-30131-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 04/18/2022] [Indexed: 11/08/2022] Open
Abstract
The U-box type ubiquitin ligase PUB44 positively regulates pattern-triggered immunity in rice. Here, we identify PBI1, a protein that interacts with PUB44. Crystal structure analysis indicates that PBI1 forms a four-helix bundle structure. PBI1 also interacts with WRKY45, a master transcriptional activator of rice immunity, and negatively regulates its activity. PBI1 is degraded upon perception of chitin, and this is suppressed by silencing of PUB44 or expression of XopP, indicating that PBI1 degradation depends on PUB44. These data suggest that PBI1 suppresses WRKY45 activity when cells are in an unelicited state, and during chitin signaling, PUB44-mediated degradation of PBI1 leads to activation of WRKY45. In addition, chitin-induced MAP kinase activation is required for WRKY45 activation and PBI1 degradation. These results demonstrate that chitin-induced activation of WRKY45 is regulated by the cooperation between MAP kinase-mediated phosphorylation and PUB44-mediated PBI1 degradation. The U-box type ubiquitin ligase PUB44 positively regulates pattern-triggered immunity in rice. Here the authors identify a PUB44 substrate whose degradation is required for activation of the WRKY45 transcription factor upon immune elicitation.
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Schmidt FL, Sürth V, Berg TK, Lin YP, Hovius JW, Kraiczy P. Interaction between Borrelia miyamotoi variable major proteins Vlp15/16 and Vlp18 with plasminogen and complement. Sci Rep 2021; 11:4964. [PMID: 33654183 PMCID: PMC7925540 DOI: 10.1038/s41598-021-84533-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 02/17/2021] [Indexed: 12/13/2022] Open
Abstract
Borrelia miyamotoi, a relapsing fever spirochete transmitted by Ixodid ticks causes B. miyamotoi disease (BMD). To evade the human host´s immune response, relapsing fever borreliae, including B. miyamotoi, produce distinct variable major proteins. Here, we investigated Vsp1, Vlp15/16, and Vlp18 all of which are currently being evaluated as antigens for the serodiagnosis of BMD. Comparative analyses identified Vlp15/16 but not Vsp1 and Vlp18 as a plasminogen-interacting protein of B. miyamotoi. Furthermore, Vlp15/16 bound plasminogen in a dose-dependent fashion with high affinity. Binding of plasminogen to Vlp15/16 was significantly inhibited by the lysine analog tranexamic acid suggesting that the protein–protein interaction is mediated by lysine residues. By contrast, ionic strength did not have an effect on binding of plasminogen to Vlp15/16. Of relevance, plasminogen bound to the borrelial protein cleaved the chromogenic substrate S-2251 upon conversion by urokinase-type plasminogen activator (uPa), demonstrating it retained its physiological activity. Interestingly, further analyses revealed a complement inhibitory activity of Vlp15/16 and Vlp18 on the alternative pathway by a Factor H-independent mechanism. More importantly, both borrelial proteins protect serum sensitive Borrelia garinii cells from complement-mediated lysis suggesting multiple roles of these two variable major proteins in immune evasion of B. miyamotoi.
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Affiliation(s)
- Frederik L Schmidt
- Institute of Medical Microbiology and Infection Control, University Hospital of Frankfurt, Goethe University, Frankfurt, Germany
| | - Valerie Sürth
- Institute of Medical Microbiology and Infection Control, University Hospital of Frankfurt, Goethe University, Frankfurt, Germany
| | - Tim K Berg
- Institute of Medical Microbiology and Infection Control, University Hospital of Frankfurt, Goethe University, Frankfurt, Germany
| | - Yi-Pin Lin
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY, USA.,Department of Biomedical Science, State University of New York at Albany, Albany, NY, USA
| | - Joppe W Hovius
- Center for Experimental and Molecular Medicine, Academic Medical Center, Amsterdam Infection and Immunity Institute, Amsterdam, The Netherlands
| | - Peter Kraiczy
- Institute of Medical Microbiology and Infection Control, University Hospital of Frankfurt, Goethe University, Frankfurt, Germany.
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Cole GB, Bateman TJ, Moraes TF. The surface lipoproteins of gram-negative bacteria: Protectors and foragers in harsh environments. J Biol Chem 2021; 296:100147. [PMID: 33277359 PMCID: PMC7857515 DOI: 10.1074/jbc.rev120.008745] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 12/02/2020] [Accepted: 12/04/2020] [Indexed: 11/06/2022] Open
Abstract
Gram-negative pathogens are enveloped by an outer membrane that serves as a double-edged sword: On the one hand, it provides a layer of protection for the bacterium from environmental insults, including other bacteria and the host immune system. On the other hand, it restricts movement of vital nutrients into the cell and provides a plethora of antigens that can be detected by host immune systems. One strategy used to overcome these limitations is the decoration of the outer surface of gram-negative bacteria with proteins tethered to the outer membrane through a lipid anchor. These surface lipoproteins (SLPs) fulfill critical roles in immune evasion and nutrient acquisition, but as more bacterial genomes are sequenced, we are beginning to discover their prevalence and their different roles and mechanisms and importantly how we can exploit them as antimicrobial targets. This review will focus on representative SLPs that gram-negative bacteria use to overcome host innate immunity, specifically the areas of nutritional immunity and complement system evasion. We elaborate on the structures of some notable SLPs required for binding target molecules in hosts and how this information can be used alongside bioinformatics to understand mechanisms of binding and in the discovery of new SLPs. This information provides a foundation for the development of therapeutics and the design of vaccine antigens.
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Affiliation(s)
- Gregory B Cole
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Thomas J Bateman
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Trevor F Moraes
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada.
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5
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Abstract
Relapsing fever (RF) is caused by several species of Borrelia; all, except two species, are transmitted to humans by soft (argasid) ticks. The species B. recurrentis is transmitted from one human to another by the body louse, while B. miyamotoi is vectored by hard-bodied ixodid tick species. RF Borrelia have several pathogenic features that facilitate invasion and dissemination in the infected host. In this article we discuss the dynamics of vector acquisition and subsequent transmission of RF Borrelia to their vertebrate hosts. We also review taxonomic challenges for RF Borrelia as new species have been isolated throughout the globe. Moreover, aspects of pathogenesis including symptomology, neurotropism, erythrocyte and platelet adhesion are discussed. We expound on RF Borrelia evasion strategies for innate and adaptive immunity, focusing on the most fundamental pathogenetic attributes, multiphasic antigenic variation. Lastly, we review new and emerging species of RF Borrelia and discuss future directions for this global disease.
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Affiliation(s)
- Job Lopez
- Department of Pediatrics, Section of Tropical Medicine, Baylor College of Medicine and Texas Children's Hospital, Houston TX, USA
| | - Joppe W Hovius
- Center for Experimental and Molecular Medicine, Amsterdam Medical centers, location Academic Medical Center, University of Amsterdam, 1105 AZ, Amsterdam, The Netherlands
| | - Sven Bergström
- Department of Molecular Biology, Umeå Center for Microbial Research, Molecular Infection Medicine Sweden, Umeå University, Umeå, Sweden
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Röttgerding F, Kraiczy P. Immune Evasion Strategies of Relapsing Fever Spirochetes. Front Immunol 2020; 11:1560. [PMID: 32793216 PMCID: PMC7390862 DOI: 10.3389/fimmu.2020.01560] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 06/12/2020] [Indexed: 12/13/2022] Open
Abstract
Relapsing fever (RF) is claimed a neglected arthropod-borne disease caused by a number of diverse human pathogenic Borrelia (B.) species. These RF borreliae are separated into the groups of tick-transmitted species including B. duttonii, B. hermsii, B. parkeri, B. turicatae, B. hispanica, B. persica, B. caucasica, and B. myiamotoi, and the louse-borne Borrelia species B. recurrentis. As typical blood-borne pathogens achieving high cell concentrations in human blood, RF borreliae (RFB) must outwit innate immunity, in particular complement as the first line of defense. One prominent strategy developed by RFB to evade innate immunity involves inactivation of complement by recruiting distinct complement regulatory proteins, e.g., C1 esterase inhibitor (C1-INH), C4b-binding protein (C4BP), factor H (FH), FH-like protein-1 (FHL-1), and factor H-related proteins FHR-1 and FHR-2, or binding of individual complement components and plasminogen, respectively. A number of multi-functional, complement and plasminogen-binding molecules from distinct Borrelia species have previously been identified and characterized, exhibiting considerable heterogeneity in their sequences, structures, gene localization, and their capacity to bind host-derived proteins. In addition, RFB possess a unique system of antigenic variation, allowing them to change the composition of surface-exposed variable major proteins, thus evading the acquired immune response of the human host. This review focuses on the current knowledge of the immune evasion strategies by RFB and highlights the role of complement-interfering and infection-associated molecules for the pathogenesis of RFB.
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Affiliation(s)
- Florian Röttgerding
- Institute of Medical Microbiology and Infection Control, University Hospital of Frankfurt, Goethe University Frankfurt, Frankfurt, Germany
| | - Peter Kraiczy
- Institute of Medical Microbiology and Infection Control, University Hospital of Frankfurt, Goethe University Frankfurt, Frankfurt, Germany
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Talagrand-Reboul E, Boyer PH, Bergström S, Vial L, Boulanger N. Relapsing Fevers: Neglected Tick-Borne Diseases. Front Cell Infect Microbiol 2018; 8:98. [PMID: 29670860 PMCID: PMC5893795 DOI: 10.3389/fcimb.2018.00098] [Citation(s) in RCA: 102] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Accepted: 03/16/2018] [Indexed: 11/13/2022] Open
Abstract
Relapsing fever still remains a neglected disease and little is known on its reservoir, tick vector and physiopathology in the vertebrate host. The disease occurs in temperate as well as tropical countries. Relapsing fever borreliae are spirochaetes, members of the Borreliaceae family which also contain Lyme disease spirochaetes. They are mainly transmitted by Ornithodoros soft ticks, but some species are vectored by ixodid ticks. Traditionally a Borrelia species is associated with a specific vector in a particular geographical area. However, new species are regularly described, and taxonomical uncertainties deserve further investigations to better understand Borrelia vector/host adaptation. The medical importance of Borrelia miyamotoi, transmitted by Ixodes spp., has recently spawned new interest in this bacterial group. In this review, recent data on tick-host-pathogen interactions for tick-borne relapsing fevers is presented, with special focus on B. miyamotoi.
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Affiliation(s)
- Emilie Talagrand-Reboul
- Early Bacterial Virulence: Borrelia Group, Université de Strasbourg, Facultés de Médecine et de Pharmacie, CHRU Strasbourg, Fédération de Médecine Translationnelle de Strasbourg, VBB EA 7290, Strasbourg, France
| | - Pierre H. Boyer
- Early Bacterial Virulence: Borrelia Group, Université de Strasbourg, Facultés de Médecine et de Pharmacie, CHRU Strasbourg, Fédération de Médecine Translationnelle de Strasbourg, VBB EA 7290, Strasbourg, France
| | - Sven Bergström
- Department of Molecular Biology, Umeå University, Umeå, Sweden
- Laboratory for Molecular Infection Medicine Sweden, Umeå University, Umeå, Sweden
| | - Laurence Vial
- CIRAD BIOS, UMR15 CIRAD/Institut National de la Recherche Agronomique “Contrôle des Maladies Animales Exotiques et Emergentes,” Equipe “Vecteurs,” Campus International de Baillarguet, Montpellier, France
| | - Nathalie Boulanger
- Early Bacterial Virulence: Borrelia Group, Université de Strasbourg, Facultés de Médecine et de Pharmacie, CHRU Strasbourg, Fédération de Médecine Translationnelle de Strasbourg, VBB EA 7290, Strasbourg, France
- Centre National de Référence Borrelia, Centre Hospitalier Universitaire, Strasbourg, France
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Luo Z, Kelleher AJ, Darwiche R, Hudspeth EM, Shittu OK, Krishnavajhala A, Schneiter R, Lopez JE, Asojo OA. Crystal Structure of Borrelia turicatae protein, BTA121, a differentially regulated gene in the tick-mammalian transmission cycle of relapsing fever spirochetes. Sci Rep 2017; 7:15310. [PMID: 29127407 PMCID: PMC5681642 DOI: 10.1038/s41598-017-14959-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Accepted: 10/19/2017] [Indexed: 12/28/2022] Open
Abstract
Tick-borne relapsing fever (RF) borreliosis is a neglected disease that is often misdiagnosed. RF species circulating in the United States include Borrelia turicatae, which is transmitted by argasid ticks. Environmental adaptation by RF Borrelia is poorly understood, however our previous studies indicated differential regulation of B. turicatae genes localized on the 150 kb linear megaplasmid during the tick-mammalian transmission cycle, including bta121. This gene is up-regulated by B. turicatae in the tick versus the mammal, and the encoded protein (BTA121) is predicted to be surface localized. The structure of BTA121 was solved by single-wavelength anomalous dispersion (SAD) using selenomethionine-derivative protein. The topology of BTA121 is unique with four helical domains organized into two helical bundles. Due to the sequence similarity of several genes on the megaplasmid, BTA121 can serve as a model for their tertiary structures. BTA121 has large interconnected tunnels and cavities that can accommodate ligands, notably long parallel helices, which have a large hydrophobic central pocket. Preliminary in-vitro studies suggest that BTA121 binds lipids, notably palmitate with a similar order of binding affinity as tablysin-15, a known palmitate-binding protein. The reported data will guide mechanistic studies to determine the role of BTA121 in the tick-mammalian transmission cycle of B. turicatae.
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Affiliation(s)
- Zhipu Luo
- Synchrotron Radiation Research Section, Macromolecular Crystallography Laboratory, National Cancer Institute, Argonne, Illinois, 60439, USA
| | - Alan J Kelleher
- National School of Tropical Medicine, Baylor College of Medicine, Houston Texas, United States of America
| | - Rabih Darwiche
- Division of Biochemistry, Department of Biology, University of Fribourg Chemin du Musée 10, CH 1700, Fribourg, Switzerland
| | - Elissa M Hudspeth
- National School of Tropical Medicine, Baylor College of Medicine, Houston Texas, United States of America
| | - Oluwatosin K Shittu
- National School of Tropical Medicine, Baylor College of Medicine, Houston Texas, United States of America
| | - Aparna Krishnavajhala
- National School of Tropical Medicine, Baylor College of Medicine, Houston Texas, United States of America
| | - Roger Schneiter
- Division of Biochemistry, Department of Biology, University of Fribourg Chemin du Musée 10, CH 1700, Fribourg, Switzerland
| | - Job E Lopez
- National School of Tropical Medicine, Baylor College of Medicine, Houston Texas, United States of America.
| | - Oluwatoyin A Asojo
- National School of Tropical Medicine, Baylor College of Medicine, Houston Texas, United States of America.
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9
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Wagemakers A, Koetsveld J, Narasimhan S, Wickel M, Deponte K, Bleijlevens B, Jahfari S, Sprong H, Karan LS, Sarksyan DS, van der Poll T, Bockenstedt LK, Bins AD, Platonov AE, Fikrig E, Hovius JW. Variable Major Proteins as Targets for Specific Antibodies against Borrelia miyamotoi. THE JOURNAL OF IMMUNOLOGY 2016; 196:4185-95. [PMID: 27076681 DOI: 10.4049/jimmunol.1600014] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 03/13/2016] [Indexed: 11/19/2022]
Abstract
Borrelia miyamotoi is a relapsing fever spirochete in Ixodes ticks that has been recently identified as a human pathogen causing hard tick-borne relapsing fever (HTBRF) across the Northern Hemisphere. No validated serologic test exists, and current serologic assays have low sensitivity in early HTBRF. To examine the humoral immune response against B. miyamotoi, we infected C3H/HeN mice with B. miyamotoi strain LB-2001 expressing variable small protein 1 (Vsp1) and demonstrated that spirochetemia was cleared after 3 d, coinciding with anti-Vsp1 IgM production. Clearance was also observed after passive transfer of immune sera to infected SCID mice. Next, we showed that anti-Vsp1 IgG eliminates Vsp1-expressing B. miyamotoi, selecting for spirochetes expressing a variable large protein (VlpC2) resistant to anti-Vsp1. The viability of Asian isolate B. miyamotoi HT31, expressing Vlp15/16 and Vlp18, was also unaffected by anti-Vsp1. Finally, in nine HTBRF patients, we demonstrated IgM reactivity to Vsp1 in two and against Vlp15/16 in four ∼1 wk after these patients tested positive for B. miyamotoi by PCR. Our data show that B. miyamotoi is able to express various variable major proteins (VMPs) to evade humoral immunity and that VMPs are antigenic in humans. We propose that serologic tests based on VMPs are of additional value in diagnosing HTBRF.
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Affiliation(s)
- Alex Wagemakers
- Center for Experimental and Molecular Medicine, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, the Netherlands; Section of Infectious Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520
| | - Joris Koetsveld
- Center for Experimental and Molecular Medicine, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, the Netherlands
| | - Sukanya Narasimhan
- Section of Infectious Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520
| | - Melvin Wickel
- Center for Experimental and Molecular Medicine, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, the Netherlands
| | - Kathleen Deponte
- Section of Infectious Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520
| | - Boris Bleijlevens
- Department of Medical Biochemistry, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, the Netherlands
| | - Seta Jahfari
- Center for Infectious Disease Control, National Institute for Public Health and the Environment, 3720 BA Bilthoven, the Netherlands
| | - Hein Sprong
- Center for Infectious Disease Control, National Institute for Public Health and the Environment, 3720 BA Bilthoven, the Netherlands
| | - Lyudmila S Karan
- Central Research Institute of Epidemiology, Moscow 111123, Russia
| | | | - Tom van der Poll
- Center for Experimental and Molecular Medicine, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, the Netherlands
| | - Linda K Bockenstedt
- Section of Rheumatology, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06510
| | - Adriaan D Bins
- Center for Experimental and Molecular Medicine, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, the Netherlands
| | | | - Erol Fikrig
- Section of Infectious Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520
| | - Joppe W Hovius
- Center for Experimental and Molecular Medicine, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, the Netherlands;
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Earnhart CG, Rhodes DVL, Smith AA, Yang X, Tegels B, Carlyon JA, Pal U, Marconi RT. Assessment of the potential contribution of the highly conserved C-terminal motif (C10) of Borrelia burgdorferi outer surface protein C in transmission and infectivity. Pathog Dis 2014; 70:176-84. [PMID: 24376161 DOI: 10.1111/2049-632x.12119] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Revised: 12/03/2013] [Accepted: 12/03/2013] [Indexed: 11/26/2022] Open
Abstract
OspC is produced by all species of the Borrelia burgdorferi sensu lato complex and is required for infectivity in mammals. To test the hypothesis that the conserved C-terminal motif (C10) of OspC is required for function in vivo, a mutant B. burgdorferi strain (B31::ospCΔC10) was created in which ospC was replaced with an ospC gene lacking the C10 motif. The ability of the mutant to infect mice was investigated using tick transmission and needle inoculation. Infectivity was assessed by cultivation, qRT-PCR, and measurement of IgG antibody responses. B31::ospCΔC10 retained the ability to infect mice by both needle and tick challenge and was competent to survive in ticks after exposure to the blood meal. To determine whether recombinant OspC protein lacking the C-terminal 10 amino acid residues (rOspCΔC10) can bind plasminogen, the only known mammalian-derived ligand for OspC, binding analyses were performed. Deletion of the C10 motif resulted in a statistically significant decrease in plasminogen binding. Although deletion of the C10 motif influenced plasminogen binding, it can be concluded that the C10 motif is not required for OspC to carry out its critical in vivo functions in tick to mouse transmission.
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Affiliation(s)
- Christopher G Earnhart
- Department of Microbiology and Immunology, Medical College of Virginia at Virginia Commonwealth University, Richmond, VA, USA; Center for the Study of Biological Complexity, Medical College of Virginia at Virginia Commonwealth University, Richmond, VA, USA
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11
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Probing the Borrelia burgdorferi surface lipoprotein secretion pathway using a conditionally folding protein domain. J Bacteriol 2011; 193:6724-32. [PMID: 21965569 DOI: 10.1128/jb.06042-11] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Surface lipoproteins of Borrelia spirochetes are important virulence determinants in the transmission and pathogenesis of Lyme disease and relapsing fever. To further define the conformational secretion requirements and to identify potential lipoprotein translocation intermediates associated with the bacterial outer membrane (OM), we generated constructs in which Borrelia burgdorferi outer surface lipoprotein A (OspA) was fused to calmodulin (CaM), a conserved eukaryotic protein undergoing calcium-dependent folding. Protein localization assays showed that constructs in which CaM was fused to full-length wild-type (wt) OspA or to an intact OspA N-terminal "tether" peptide retained their competence for OM translocation even in the presence of calcium. In contrast, constructs in which CaM was fused to truncated or mutant OspA N-terminal tether peptides were targeted to the periplasmic leaflet of the OM in the presence of calcium but could be flipped to the bacterial surface upon calcium chelation. This indicated that in the absence of an intact tether peptide, unfolding of the CaM moiety was required in order to facilitate OM traversal. Together, these data further support a periplasmic tether peptide-mediated mechanism to prevent premature folding of B. burgdorferi surface lipoproteins. The specific shift in the OM topology of sequence-identical lipopeptides due to a single-variable change in environmental conditions also indicates that surface-bound Borrelia lipoproteins can localize transiently to the periplasmic leaflet of the OM.
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12
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Specificity and role of the Borrelia burgdorferi CtpA protease in outer membrane protein processing. J Bacteriol 2011; 193:5759-65. [PMID: 21856844 DOI: 10.1128/jb.05622-11] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
To further characterize the function of the Borrelia burgdorferi C-terminal protease CtpA, we used site-directed mutagenesis to alter the putative CtpA cleavage site of one of its known substrates, the outer membrane (OM) porin P13. These mutations resulted in only partial blockage of P13 processing. Ectopic expression of a C-terminally truncated P13 in B. burgdorferi indicated that the C-terminal peptide functions as a safeguard against misfolding or mislocalization prior to its proteolytic removal by CtpA. In a parallel study of Borrelia burgdorferi lipoprotein sorting mechanisms, we observed a lower-molecular-weight variant of surface lipoprotein OspC that was particularly prominent with OspC mutants that mislocalized to the periplasm or contained C-terminal epitope tags. Further investigation revealed that the variant resulted from C-terminal proteolysis by CtpA. Together, these findings indicate that CtpA rather promiscuously targets polypeptides that lack structurally constrained C termini, as proteolysis appears to occur independently of a specific peptide recognition sequence. Low-level processing of surface lipoproteins such as OspC suggests the presence of a CtpA-dependent quality control mechanism that may sense proper translocation of integral outer membrane proteins and surface lipoproteins by detecting the release of C-terminal peptides.
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13
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Disulfide-mediated oligomer formation in Borrelia burgdorferi outer surface protein C, a critical virulence factor and potential Lyme disease vaccine candidate. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2011; 18:901-6. [PMID: 21525304 DOI: 10.1128/cvi.05004-11] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Borrelia burgdorferi OspC is an outer membrane lipoprotein required for the establishment of infection in mammals. Due to its universal distribution among B. burgdorferi sensu lato strains and high antigenicity, it is being explored for the development of a next-generation Lyme disease vaccine. An understanding of the surface presentation of OspC will facilitate efforts to maximize its potential as a vaccine candidate. OspC forms homodimers at the cell surface, and it has been hypothesized that it may also form oligomeric arrays. Here, we employ site-directed mutagenesis to test the hypothesis that interdimeric disulfide bonds at cysteine 130 (C130) mediate oligomerization. B. burgdorferi B31 ospC was replaced with a C130A substitution mutant to yield strain B31::ospC(C130A). Recombinant protein was also generated. Disulfide-bond-dependent oligomer formation was demonstrated and determined to be dependent on C130. Oligomerization was not required for in vivo function, as B31::ospC(C130A) retained infectivity and disseminated normally. The total IgG response and the induced isotype pattern were similar between mice infected with untransformed B31 and those infected with the B31::ospC(C130A) strain. These data indicate that the immune response to OspC is not significantly altered by formation of OspC oligomers, a finding that has significant implications in Lyme disease vaccine design.
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14
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Abstract
The dimeric OspC/Vsp family surface lipoproteins of Borrelia spirochetes are crucial to the transmission and persistence of Lyme borreliosis and tick-borne relapsing fever. However, the requirements for their proper surface display remained undefined. In previous studies, we showed that localization of Borrelia burgdorferi monomeric surface lipoprotein OspA was dependent on residues in the N-terminal "tether" peptide. Here, site-directed mutagenesis of the B. burgdorferi OspC tether revealed two distinct regions affecting either release from the inner membrane or translocation through the outer membrane. Determinants of both of these steps appear consolidated within a single region of the Borrelia turicatae Vsp1 tether. Periplasmic OspC mutants still were able to form dimers. Their localization defect could be rescued by the addition of an apparently structure-destabilizing C-terminal epitope tag but not by coexpression with wild-type OspC. Furthermore, disruption of intermolecular Vsp1 salt bridges blocked dimerization but not surface localization of the resulting Vsp1 monomers. Together, these results suggest that Borrelia OspC/Vsp1 surface lipoproteins traverse the periplasm and the outer membrane as unfolded monomeric intermediates and assemble into their functional multimeric folds only upon reaching the spirochetal surface.
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15
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Gandhi G, Londoño D, Whetstine CR, Sethi N, Kim KS, Zückert WR, Cadavid D. Interaction of variable bacterial outer membrane lipoproteins with brain endothelium. PLoS One 2010; 5:e13257. [PMID: 21063459 PMCID: PMC2962627 DOI: 10.1371/journal.pone.0013257] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Accepted: 09/07/2010] [Indexed: 11/29/2022] Open
Abstract
Background Previously we reported that the variable outer membrane lipoprotein Vsp1 from the relapsing fever spirochete Borrelia turicatae disseminates from blood to brain better than the closely related Vsp2 [1]. Here we studied the interaction between Vsp1 and Vsp2 with brain endothelium in more detail. Methodology/Principal Findings We compared Vsp1 to Vsp2 using human brain microvascular endothelial cell (HBMEC) association assays with aminoacid radiolabeled Vsp-expressing clones of recombinant Borrelia burgdorferi and lanthanide-labeled purified lipidated Vsp1 (LVsp1) and Vsp2 (LVsp2) and inoculations of the lanthanide-labeled proteins into mice. The results showed that heterologous expression of LVsp1 or LVsp2 in B. burgdorferi increased its association with HBMEC to a similar degree. Purified lanthanide-labeled lipidated Vsp1 (LVsp1) and LVsp2 by themselves were capable of associating with HBMEC. The association of LVsp1 with brain endothelium was time-dependent, saturable, and required the lipidation. The association of Vsp1 with HBMEC was inhibited by incubation at lower temperature or with excess unlabeled LVsp1 or LVsp2 but not with excess rVsp1 or mouse albumin or an anti Vsp1 monoclonal antibody. The association of LVsp2 with HBMEC and its movement from blood to brain parenchyma significantly increased in the presence of LVsp1. Conclusions/Significance Variable bacterial outer membrane lipoproteins interact with brain endothelium differently; the lipidation and variable features at the protein dome region are key modulators of this interaction.
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Affiliation(s)
- Gaurav Gandhi
- Department of Neurology and Neuroscience and Center for the Study of Emerging Pathogens at UMDNJ-New Jersey Medical School, Newark, New Jersey, United States of America
| | - Diana Londoño
- Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Department of Neurology and Neuroscience and Center for the Study of Emerging Pathogens at UMDNJ-New Jersey Medical School, Newark, New Jersey, United States of America
| | - Christine R. Whetstine
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, Kansas, United States of America
| | - Nilay Sethi
- Department of Neurology and Neuroscience and Center for the Study of Emerging Pathogens at UMDNJ-New Jersey Medical School, Newark, New Jersey, United States of America
| | - Kwang S. Kim
- Pediatric Infectious Diseases, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Wolfram R. Zückert
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, Kansas, United States of America
| | - Diego Cadavid
- Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Department of Neurology and Neuroscience and Center for the Study of Emerging Pathogens at UMDNJ-New Jersey Medical School, Newark, New Jersey, United States of America
- * E-mail:
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16
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Evolution and distribution of the ospC Gene, a transferable serotype determinant of Borrelia burgdorferi. mBio 2010; 1. [PMID: 20877579 PMCID: PMC2945197 DOI: 10.1128/mbio.00153-10] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2010] [Accepted: 08/18/2010] [Indexed: 02/06/2023] Open
Abstract
Borrelia burgdorferi, an emerging bacterial pathogen, is maintained in nature by transmission from one vertebrate host to another by ticks. One of the few antigens against which mammals develop protective immunity is the highly polymorphic OspC protein, encoded by the ospC gene on the cp26 plasmid. Intragenic recombination among ospC genes is known, but the extent to which recombination extended beyond the ospC locus itself is undefined. We accessed and supplemented collections of DNA sequences of ospC and other loci from ticks in three U.S. regions (the Northeast, the Midwest, and northern California); a total of 839 ospC sequences were analyzed. Three overlapping but distinct populations of B. burgdorferi corresponded to the geographic regions. In addition, we sequenced 99 ospC flanking sequences from different lineages and compared the complete cp26 sequences of 11 strains as well as the cp26 bbb02 loci of 56 samples. Besides recombinations with traces limited to the ospC gene itself, there was evidence of lateral gene transfers that involved (i) part of the ospC gene and one of the two flanks or (ii) the entire ospC gene and different lengths of both flanks. Lateral gene transfers resulted in different linkages between the ospC gene and loci of the chromosome or other plasmids. By acquisition of the complete part or a large part of a novel ospC gene, an otherwise adapted strain would assume a new serotypic identity, thereby being comparatively fitter in an area with a high prevalence of immunity to existing OspC types. The tick-borne zoonosis Lyme borreliosis is increasing in incidence and spreading geospatially in North America. Further understanding of the evolution and genetics of its cause, Borrelia burgdorferi, in its environments fosters progress toward ecologically based control efforts. By means of DNA sequencing of a large sample collection of the pathogen from across the United States, we studied the gene for the bacterium’s highly diverse OspC protein, protective immunity against which develops in animals. We found that the distributions and frequencies of types of OspC genes differed between populations of B. burgdorferi in the Northeast, the Midwest, and California. Over time, OspC genes were transferred between strains through recombinations involving the whole or parts of the gene and one or both flanks. Acquisitions of OspC genes that are novel for the region confer to recipients unique identities to host immune systems and, presumably, selective advantage when immunity to existing types is widespread among hosts.
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17
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Schulze RJ, Chen S, Kumru OS, Zückert WR. Translocation of Borrelia burgdorferi surface lipoprotein OspA through the outer membrane requires an unfolded conformation and can initiate at the C-terminus. Mol Microbiol 2010; 76:1266-78. [PMID: 20398211 DOI: 10.1111/j.1365-2958.2010.07172.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Borrelia burgdorferi surface lipoproteins are essential to the pathogenesis of Lyme borreliosis, but the mechanisms responsible for their localization are only beginning to emerge. We have previously demonstrated the critical nature of the amino-terminal 'tether' domain of the mature lipoprotein for sorting a fluorescent reporter to the Borrelia cell surface. Here, we show that individual deletion of four contiguous residues within the tether of major surface lipoprotein OspA results in its inefficient translocation across the Borrelia outer membrane. Intriguingly, C-terminal epitope tags of these N-terminal deletion mutants were selectively surface-exposed. Fold-destabilizing C-terminal point mutations and deletions did not block OspA secretion, but rather restored one of the otherwise periplasmic tether mutants to the bacterial surface. Together, these data indicate that disturbance of a confined tether feature leads to premature folding of OspA in the periplasm and thereby prevents secretion through the outer membrane. Furthermore, they suggest that OspA emerges tail-first on the bacterial surface, yet independent of a specific C-terminal targeting peptide sequence.
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Affiliation(s)
- Ryan J Schulze
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Mail Stop 3029, 3901 Rainbow Boulevard, Kansas City, KS 66160, USA
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Mehra R, Londoño D, Sondey M, Lawson C, Cadavid D. Structure-function investigation of vsp serotypes of the spirochete Borrelia hermsii. PLoS One 2009; 4:e7597. [PMID: 19888463 PMCID: PMC2766631 DOI: 10.1371/journal.pone.0007597] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2009] [Accepted: 09/07/2009] [Indexed: 11/30/2022] Open
Abstract
Background Relapsing fever (RF) spirochetes are notable for multiphasic antigenic variation of polymorphic outer membrane lipoproteins, a phenomenon responsible for immune evasion. An additional role in tissue localization is suggested by the finding that isogenic serotypes 1 (Bt1) and 2 (Bt2) of the RF spirochete Borrelia turicatae, which differ only in the Vsp they express, exhibit marked differences in clinical disease severity and tissue localization during infection. Methodology/Principal Findings Here we used known vsp DNA sequences encoding for B. turicatae and Borrelia hermsii Vsp proteins with variable regions and then studied whether there are differences in disease expression and tissue localization of their corresponding serotypes during mouse infection. For sequence and structural comparisons we focused exclusively on amino acid residues predicted to project away from the spirochetes surface, referred to as the Vsp dome. Disease severity and tissue localization were studied during persistent infection with individual or mixed serotypes in SCID mice. The results showed that all Vsp domes clustered into 3 main trunks, with the domes for B. turicatae Vsp1 (BtVsp1) and BtVsp2 clustering into separate ones. B. hermsii serotypes whose Vsp domes clustered with the BtVsp1 dome were less virulent but localized to the brain more. The BtVsp2 dome was the oddball among all and Bt2 was the only serotype that caused severe arthritis. Conclusion/Significance These findings indicate that there is significant variability in Vsp dome structure, disease severity, and tissue localization among serotypes of B. hermsii.
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Affiliation(s)
- Rohit Mehra
- Department of Neurology, Neuroscience and Center for Emerging Pathogens at UMDNJ-New Jersey Medical School, Newark, New Jersey, United States of America
| | - Diana Londoño
- Department of Neurology, Neuroscience and Center for Emerging Pathogens at UMDNJ-New Jersey Medical School, Newark, New Jersey, United States of America
- Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital, Charlestown, Massachusetts, United States of America
| | - Marie Sondey
- Department of Neurology, Neuroscience and Center for Emerging Pathogens at UMDNJ-New Jersey Medical School, Newark, New Jersey, United States of America
| | - Catherine Lawson
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey, United States of America
| | - Diego Cadavid
- Department of Neurology, Neuroscience and Center for Emerging Pathogens at UMDNJ-New Jersey Medical School, Newark, New Jersey, United States of America
- Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital, Charlestown, Massachusetts, United States of America
- * E-mail:
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