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Bowen HG, Kenedy MR, Johnson DK, MacKerell AD, Akins DR. Identification of a novel transport system in Borrelia burgdorferi that links the inner and outer membranes. Pathog Dis 2023; 81:ftad014. [PMID: 37385817 PMCID: PMC10353723 DOI: 10.1093/femspd/ftad014] [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: 04/20/2023] [Revised: 06/19/2023] [Accepted: 06/27/2023] [Indexed: 07/01/2023] Open
Abstract
Borrelia burgdorferi, the spirochete that causes Lyme disease, is a diderm organism that is similar to Gram-negative organisms in that it contains both an inner and outer membrane. Unlike typical Gram-negative organisms, however, B. burgdorferi lacks lipopolysaccharide (LPS). Using computational genome analyses and structural modeling, we identified a transport system containing six proteins in B. burgdorferi that are all orthologs to proteins found in the lipopolysaccharide transport (LPT) system that links the inner and outer membranes of Gram-negative organisms and is responsible for placing LPS on the surface of these organisms. While B. burgdorferi does not contain LPS, it does encode over 100 different surface-exposed lipoproteins and several major glycolipids, which like LPS are also highly amphiphilic molecules, though no system to transport these molecules to the borrelial surface is known. Accordingly, experiments supplemented by molecular modeling were undertaken to determine whether the orthologous LPT system identified in B. burgdorferi could transport lipoproteins and/or glycolipids to the borrelial outer membrane. Our combined observations strongly suggest that the LPT transport system does not transport lipoproteins to the surface. Molecular dynamic modeling, however, suggests that the borrelial LPT system could transport borrelial glycolipids to the outer membrane.
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Affiliation(s)
- Hannah G Bowen
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, 940 Stanton L. Young Blvd., BMSB 1053 Oklahoma City, OK 73104, United States
| | - Melisha R Kenedy
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, 940 Stanton L. Young Blvd., BMSB 1053 Oklahoma City, OK 73104, United States
| | - David K Johnson
- Shenkel Structural Biology Center, Molecular Graphics and Modeling Laboratory and the Computational Biology Core, University of Kansas, 2034 Becker Drive Lawrence, Kansas 66047, United States
| | - Alexander D MacKerell
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore 20 North Pine Street Baltimore, Maryland 21201, United States
| | - Darrin R Akins
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, 940 Stanton L. Young Blvd., BMSB 1053 Oklahoma City, OK 73104, United States
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Fleury C, Su YC, Hallström T, Sandblad L, Zipfel PF, Riesbeck K. Identification of a Haemophilus influenzae factor H-Binding lipoprotein involved in serum resistance. THE JOURNAL OF IMMUNOLOGY 2014; 192:5913-23. [PMID: 24835392 DOI: 10.4049/jimmunol.1303449] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Haemophilus influenzae is a Gram-negative human pathogen that resides in the upper respiratory tract. Encapsulated H. influenzae type b (Hib) and type f (Hif) are the most common serotypes associated with invasive disease. H. influenzae displays various strategies to circumvent the host innate immune response, including the bactericidal effect of the complement system. In this study, we identified an H. influenzae lipoprotein having the ability to bind factor H (FH), the major regulator of the alternative pathway of complement activation. This protein, named protein H (PH), was surface exposed and was found in all clinical Hib and Hif isolates tested. Deletion of the gene encoding for PH (lph) in Hib and Hif significantly reduced the interaction between bacteria and FH. When Hib and Hif PH variants were separately expressed in nontypeable (unencapsulated) H. influenzae, which did not bind FH, an increased FH affinity was observed. We recombinantly expressed the two PH variants in Escherichia coli, and despite sharing only 56% identical amino acids, both FH-binding Haemophilus proteins similarly interacted with the complement regulator FH short consensus repeats 7 and 18-20. Importantly, Hib and Hif resistance against the bactericidal effect of human serum was significantly reduced when bacterial mutants devoid of PH were tested. In conclusion, we have characterized a hitherto unknown bacterial protein that is crucial for mediating an interaction between the human pathogen H. influenzae and FH. This novel interaction is important for H. influenzae resistance against complement activation and will consequently promote bacterial pathogenesis.
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Affiliation(s)
- Christophe Fleury
- Medical Microbiology, Department of Laboratory Medicine Malmö, Lund University, SE-205 02 Malmö, Sweden
| | - Yu-Ching Su
- Medical Microbiology, Department of Laboratory Medicine Malmö, Lund University, SE-205 02 Malmö, Sweden
| | - Teresia Hallström
- Department of Infection Biology, Leibniz Institute for Natural Product Research and Infection Biology, Faculty of Biology, Friedrich Schiller University, 07745 Jena, Germany; and
| | - Linda Sandblad
- Department of Molecular Biology, Umeå University, SE-901 87 Umea, Sweden
| | - Peter F Zipfel
- Department of Infection Biology, Leibniz Institute for Natural Product Research and Infection Biology, Faculty of Biology, Friedrich Schiller University, 07745 Jena, Germany; and
| | - Kristian Riesbeck
- Medical Microbiology, Department of Laboratory Medicine Malmö, Lund University, SE-205 02 Malmö, Sweden;
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Brangulis K, Tars K, Petrovskis I, Kazaks A, Ranka R, Baumanis V. Structure of an outer surface lipoprotein BBA64 from the Lyme disease agentBorrelia burgdorferiwhich is critical to ensure infection after a tick bite. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2013; 69:1099-107. [DOI: 10.1107/s0907444913005726] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Accepted: 02/27/2013] [Indexed: 11/10/2022]
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Brangulis K, Petrovskis I, Kazaks A, Baumanis V, Tars K. Structural characterization of the Borrelia burgdorferi outer surface protein BBA73 implicates dimerization as a functional mechanism. Biochem Biophys Res Commun 2013; 434:848-53. [DOI: 10.1016/j.bbrc.2013.04.028] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Accepted: 04/02/2013] [Indexed: 11/24/2022]
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Clifton DR, Nolder CL, Hughes JL, Nowalk AJ, Carroll JA. Regulation and expression of bba66 encoding an immunogenic infection-associated lipoprotein in Borrelia burgdorferi. Mol Microbiol 2006; 61:243-58. [PMID: 16824109 DOI: 10.1111/j.1365-2958.2006.05224.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
When Borrelia burgdorferi (Bb) is transmitted from a tick vector to a mammalian host the spirochaete alters gene expression, allowing for adaptation to the new host. We evaluated the regulation of paralogous gene family (pgf) 54 members in response to environmental cues and focused our efforts on determining the molecular mechanisms influencing bba66 expression. By qRT-PCR, bba65, bba66, bba71 and bba73 displayed regulation similar to ospC under mammalian-like conditions. Of the pgf 54 members, bba66 demonstrated the greatest and second greatest change in expression in response to pH or temperature shift respectively. Furthermore, Bb-infected mice and patients with early disseminated Lyme disease produced detectable antibodies to BBA66. A protein(s) active in Bb at pH 7 was able to interact with the bba66 upstream region and was specific as bba64 and ospC promoters were unable to out-compete for binding. bba66 promoter mapping revealed putative sigma70 and sigmaS consensus sequences, enabling us to narrow the protein binding site to a region within an imperfect inverted repeat upstream of the -35 region. Moreover, BBA66 production is associated with an infectious phenotype, and loss of either sigmaN or sigmaS resulted in loss of BBA66. Promoter-GFP fusion analysis indicated that the sigma70 and/or sigmaS consensus sequences alone were not sufficient to initiate transcription and a portion of the upstream inverted repeat was required. These results suggest a primary role for BBA66 in Bb transmission and infection.
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Affiliation(s)
- Dawn R Clifton
- Department of Molecular Genetics and Biochemistry, University of Pittsburgh School of Medicine, W1145 Biomedical Science Tower, 200 Lothrop Street, Pittsburgh, PA 15261, USA
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Kraiczy P, Würzner R. Complement escape of human pathogenic bacteria by acquisition of complement regulators. Mol Immunol 2006; 43:31-44. [PMID: 16011850 DOI: 10.1016/j.molimm.2005.06.016] [Citation(s) in RCA: 112] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Pathogenic micro-organisms employ a broad range of strategies to survive in and to persistently infect the human host. Far from being completely understood by which highly sophisticated means invading pathogens overcome the host's destructive immune defence, there is a growing body of evidence on particular mechanisms which play a pivotal role for immune evasion. This review focuses on evasion of medically and scientifically important bacteria by acquisition of host derived fluid-phase complement regulatory proteins, in particular factor H, FHL-1, and C4b binding protein. Expression of microbial surface molecules binding to human complement regulators and thus fixing them in a functionally active state allows pathogens to inhibit and finely regulate complement activation directly on their surface. Further studies on the utilization of host complement regulatory proteins will likely have a marked impact on a more efficient and specific clinical treatment.
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Affiliation(s)
- Peter Kraiczy
- Institute of Medical Microbiology, University Hospital of Frankfurt, Paul-Ehrlich-Str. 40, D-60596 Frankfurt, Germany.
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Alitalo A, Meri T, Comstedt P, Jeffery L, Tornberg J, Strandin T, Lankinen H, Bergström S, Cinco M, Vuppala SR, Akins DR, Meri S. Expression of complement factor H binding immunoevasion proteins in Borrelia garinii isolated from patients with neuroborreliosis. Eur J Immunol 2005; 35:3043-53. [PMID: 16208765 DOI: 10.1002/eji.200526354] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The Lyme disease-pathogen Borrelia burgdorferi binds the complement inhibitor factor H (FH) to its outer surface protein E- (OspE) and BbA68-families of lipoproteins. In earlier studies, only serum-resistant strains of the genospecies B. burgdorferi sensu stricto or B. afzelii, but not serum-sensitive B. garinii strains, have been shown to bind FH. Since B. garinii often causes neuroborreliosis in man, we have readdressed the interactions of B. garinii with FH. B. garinii 50/97 strain did not express FH-binding proteins. By transforming the B. garinii 50/97 strain with an OspE-encoding gene from complement-resistant B. burgdorferi (ospE-297), its resistance to serum killing could be increased. OspE genes were detected and cloned from the B. garinii BITS, Pistoia and 40/97 strains by PCR and sequencing. The deduced amino acid sequences differed in an N-terminal lysine-rich FH-binding region from OspE sequences of resistant strains. Recombinant B. garinii BITS OspE protein was found to have a considerably lower FH-binding activity than the B. burgdorferi sensu stricto 297 OspE protein P21 (P21-297). Unlike bacteria that had been kept in culture for a long time, neurovirulent B. garinii strains from neuroborreliosis patients were found to express approximately 27-kDa FH-binding proteins. These were not recognized by polyclonal anti-OspE or anti-BbA68 antibodies. We conclude that B. garinii strains carry ospE genes but have a decreased expression of OspE proteins and a reduced ability to bind FH, especially when grown for prolonged periods in vitro. Recently isolated neuroinvasive B. garinii strains, however, can express FH-binding proteins, which may contribute to the virulence of neuroborreliosis-causing B. garinii strains.
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Affiliation(s)
- Antti Alitalo
- Department of Bacteriology and Immunology, Haartman Institute and Helsinki University Central Hospital, University of Helsinki, Helsinki, Finland
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Brooks CS, Vuppala SR, Jett AM, Alitalo A, Meri S, Akins DR. Complement Regulator-Acquiring Surface Protein 1 Imparts Resistance to Human Serum inBorrelia burgdorferi. THE JOURNAL OF IMMUNOLOGY 2005; 175:3299-308. [PMID: 16116222 DOI: 10.4049/jimmunol.175.5.3299] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Factor H and factor H-like protein 1 (FH/FHL-1) are soluble serum proteins that negatively regulate the alternative pathway of complement. It is now well recognized that many pathogenic bacteria, including Borrelia burgdorferi, bind FH/FHL-1 on their cell surface to evade complement-mediated destruction during infection. Recently, it was suggested that B. burgdorferi open reading frame bbA68, known as complement regulator-acquiring surface protein 1 (CRASP-1), encodes the major FH/FHL-1-binding protein of B. burgdorferi. However, because several other proteins have been identified on the surface of B. burgdorferi that also can bind FH/FHL-1, it is presently unclear what role CRASP-1 plays in serum resistance. To examine the contribution of CRASP-1 in serum resistance, we generated a B. burgdorferi mutant that does not express CRASP-1. The B. burgdorferi CRASP-1 mutant, designated B31cF-CRASP-1, was found to be as susceptible to human serum as a wild-type strain of Borrelia garinii 50 known to be sensitive to human serum. To further examine the role of CRASP-1 in serum resistance, we also created a shuttle vector that expresses CRASP-1 from the native B. burgdorferi gene, which was designated pKFSS-1::CRASP-1. When the pKFSS-1::CRASP-1 construct was transformed into the B. burgdorferi B31cF-CRASP-1 mutant, wild-type levels of serum resistance were restored. Additionally, when pKFSS-1::CRASP-1 was transformed into the serum-sensitive B. garinii 50 isolate, human serum resistance was imparted on this strain to a level indistinguishable from wild-type B. burgdorferi. The combined data led us to conclude that CRASP-1 expression is necessary for B. burgdorferi to resist killing by human serum.
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Affiliation(s)
- Chad S Brooks
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
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Cordes FS, Roversi P, Kraiczy P, Simon MM, Brade V, Jahraus O, Wallis R, Skerka C, Zipfel PF, Wallich R, Lea SM. A novel fold for the factor H-binding protein BbCRASP-1 of Borrelia burgdorferi. Nat Struct Mol Biol 2005; 12:276-7. [PMID: 15711564 DOI: 10.1038/nsmb902] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2004] [Accepted: 01/25/2005] [Indexed: 11/09/2022]
Abstract
Borrelia burgdorferi, a spirochete transmitted to human hosts during feeding of infected Ixodes ticks, is the causative agent of Lyme disease. Serum-resistant B. burgdorferi strains cause a chronic, multisystemic form of the disease and bind complement factor H (FH) and FH-like protein 1 (FHL-1) on the spirochete surface. Here we report the atomic structure for the key FHL-1- and FH-binding protein BbCRASP-1 and reveal a homodimer that presents a novel target for drug design.
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Affiliation(s)
- Frank S Cordes
- Laboratory of Molecular Biophysics, Department of Biochemistry, South Parks Road, Oxford, UK
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