1
|
Rodríguez de Córdoba S. Genetic variability shapes the alternative pathway complement activity and predisposition to complement-related diseases. Immunol Rev 2023; 313:71-90. [PMID: 36089777 PMCID: PMC10086816 DOI: 10.1111/imr.13131] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The implementation of next-generation sequencing technologies has provided a sharp picture of the genetic variability in the components and regulators of the alternative pathway (AP) of the complement system and has revealed the association of many AP variants with different rare and common diseases. An important finding that has emerged from these analyses is that each of these complement-related diseases associate with genetic variants altering specific aspects of the activation and regulation of the AP. These genotype-phenotype correlations have provided valuable insights into their pathogenic mechanisms with important diagnostic and therapeutic implications. While genetic variants in coding regions and structural variants are reasonably well characterized and occasionally have been instrumental to uncover unknown features of the complement proteins, data about complement expressed quantitative trait loci are still very limited. A crucial task for future studies will be to identify these quantitative variations and to determine their impact in the overall activity of the AP. This is fundamental as it is now clear that the consequences of genetic variants in the AP are additive and that susceptibility or resistance to disease is the result of specific combinations of genetic variants in different complement components and regulators ("complotypes").
Collapse
|
2
|
Macleod OJS, Bart JM, MacGregor P, Peacock L, Savill NJ, Hester S, Ravel S, Sunter JD, Trevor C, Rust S, Vaughan TJ, Minter R, Mohammed S, Gibson W, Taylor MC, Higgins MK, Carrington M. A receptor for the complement regulator factor H increases transmission of trypanosomes to tsetse flies. Nat Commun 2020; 11:1326. [PMID: 32165615 PMCID: PMC7067766 DOI: 10.1038/s41467-020-15125-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 02/15/2020] [Indexed: 11/09/2022] Open
Abstract
Persistent pathogens have evolved to avoid elimination by the mammalian immune system including mechanisms to evade complement. Infections with African trypanosomes can persist for years and cause human and animal disease throughout sub-Saharan Africa. It is not known how trypanosomes limit the action of the alternative complement pathway. Here we identify an African trypanosome receptor for mammalian factor H, a negative regulator of the alternative pathway. Structural studies show how the receptor binds ligand, leaving inhibitory domains of factor H free to inactivate complement C3b deposited on the trypanosome surface. Receptor expression is highest in developmental stages transmitted to the tsetse fly vector and those exposed to blood meals in the tsetse gut. Receptor gene deletion reduced tsetse infection, identifying this receptor as a virulence factor for transmission. This demonstrates how a pathogen evolved a molecular mechanism to increase transmission to an insect vector by exploitation of a mammalian complement regulator.
Collapse
Affiliation(s)
- Olivia J S Macleod
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW, UK
| | - Jean-Mathieu Bart
- Intertryp, IRD, Cirad, University of Montpellier, Montpellier, France
| | - Paula MacGregor
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW, UK
| | - Lori Peacock
- School of Biological Sciences, University of Bristol, Bristol, BS8 1UG, UK
| | - Nicholas J Savill
- Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, King's Buildings, West Mains Road, Edinburgh, EH9 3JT, UK
| | - Svenja Hester
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Sophie Ravel
- Intertryp, IRD, Cirad, University of Montpellier, Montpellier, France
| | - Jack D Sunter
- Department of Biological and Medical Sciences, Oxford Brookes University, Gipsy Lane, Oxford, OX3 0BP, UK
| | - Camilla Trevor
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW, UK
- Department of Antibody Discovery and Protein Engineering, AstraZeneca R&D, Granta Park, Cambridge, CB21 6GH, UK
| | - Steven Rust
- Department of Antibody Discovery and Protein Engineering, AstraZeneca R&D, Granta Park, Cambridge, CB21 6GH, UK
| | - Tristan J Vaughan
- Department of Antibody Discovery and Protein Engineering, AstraZeneca R&D, Granta Park, Cambridge, CB21 6GH, UK
| | - Ralph Minter
- Department of Antibody Discovery and Protein Engineering, AstraZeneca R&D, Granta Park, Cambridge, CB21 6GH, UK
| | - Shabaz Mohammed
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Wendy Gibson
- School of Biological Sciences, University of Bristol, Bristol, BS8 1UG, UK
| | - Martin C Taylor
- Faculty of Infectious and Tropical diseases, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
| | - Matthew K Higgins
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK.
| | - Mark Carrington
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW, UK.
| |
Collapse
|
3
|
Osborne AJ, Nan R, Miller A, Bhatt JS, Gor J, Perkins SJ. Two distinct conformations of factor H regulate discrete complement-binding functions in the fluid phase and at cell surfaces. J Biol Chem 2018; 293:17166-17187. [PMID: 30217822 PMCID: PMC6222095 DOI: 10.1074/jbc.ra118.004767] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 09/10/2018] [Indexed: 11/06/2022] Open
Abstract
Factor H (FH) is the major regulator of C3b in the alternative pathway of the complement system in immunity. FH comprises 20 short complement regulator (SCR) domains, including eight glycans, and its Y402H polymorphism predisposes those who carry it to age-related macular degeneration. To better understand FH complement binding and self-association, we have studied the solution structures of both the His-402 and Tyr-402 FH allotypes. Analytical ultracentrifugation revealed that up to 12% of both FH allotypes self-associate, and this was confirmed by small-angle X-ray scattering (SAXS), MS, and surface plasmon resonance analyses. SAXS showed that monomeric FH has a radius of gyration (Rg ) of 7.2-7.8 nm and a length of 25 nm. Starting from known structures for the SCR domains and glycans, the SAXS data were fitted using Monte Carlo methods to determine atomistic structures of monomeric FH. The analysis of 29,715 physically realistic but randomized FH conformations resulted in 100 similar best-fit FH structures for each allotype. Two distinct molecular structures resulted that showed either an extended N-terminal domain arrangement with a folded-back C terminus or an extended C terminus and a folded-back N terminus. These two structures are the most accurate to date for glycosylated full-length FH. To clarify FH functional roles in host protection, crystal structures for the FH complexes with C3b and C3dg revealed that the extended N-terminal conformation accounted for C3b fluid-phase regulation, the extended C-terminal conformation accounted for C3d binding, and both conformations accounted for bivalent FH binding to glycosaminoglycans on the target cell surface.
Collapse
Affiliation(s)
- Amy J Osborne
- From the Department of Structural and Molecular Biology, Darwin Building, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Ruodan Nan
- From the Department of Structural and Molecular Biology, Darwin Building, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Ami Miller
- From the Department of Structural and Molecular Biology, Darwin Building, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Jayesh S Bhatt
- From the Department of Structural and Molecular Biology, Darwin Building, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Jayesh Gor
- From the Department of Structural and Molecular Biology, Darwin Building, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Stephen J Perkins
- From the Department of Structural and Molecular Biology, Darwin Building, University College London, Gower Street, London WC1E 6BT, United Kingdom
| |
Collapse
|
4
|
Ram S, Shaughnessy J, de Oliveira RB, Lewis LA, Gulati S, Rice PA. Gonococcal lipooligosaccharide sialylation: virulence factor and target for novel immunotherapeutics. Pathog Dis 2017; 75:3777971. [PMID: 28460033 PMCID: PMC5449626 DOI: 10.1093/femspd/ftx049] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2017] [Accepted: 04/26/2017] [Indexed: 12/13/2022] Open
Abstract
Gonorrhea has become resistant to most conventional antimicrobials used in clinical practice. The global spread of multidrug-resistant isolates of Neisseria gonorrhoeae could lead to an era of untreatable gonorrhea. New therapeutic modalities with novel mechanisms of action that do not lend themselves to the development of resistance are urgently needed. Gonococcal lipooligosaccharide (LOS) sialylation is critical for complement resistance and for establishing infection in humans and experimental mouse models. Here we describe two immunotherapeutic approaches that target LOS sialic acid: (i) a fusion protein that comprises the region in the complement inhibitor factor H (FH) that binds to sialylated gonococci and IgG Fc (FH/Fc fusion protein) and (ii) analogs of sialic acid that are incorporated into LOS but fail to protect the bacterium against killing. Both molecules showed efficacy in the mouse vaginal colonization model of gonorrhea and may represent promising immunotherapeutic approaches to target multidrug-resistant isolates. Disabling key gonococcal virulence mechanisms is an effective therapeutic strategy because the reduction of virulence is likely to be accompanied by a loss of fitness, rapid elimination by host immunity and consequently, decreased transmission.
Collapse
Affiliation(s)
- Sanjay Ram
- Division of Infectious Diseases and Immunology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Jutamas Shaughnessy
- Division of Infectious Diseases and Immunology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Rosane B. de Oliveira
- Division of Infectious Diseases and Immunology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Lisa A. Lewis
- Division of Infectious Diseases and Immunology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Sunita Gulati
- Division of Infectious Diseases and Immunology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Peter A. Rice
- Division of Infectious Diseases and Immunology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| |
Collapse
|
5
|
Caesar JJE, Lavender H, Ward PN, Exley RM, Eaton J, Chittock E, Malik TH, Goiecoechea De Jorge E, Pickering MC, Tang CM, Lea SM. Competition between antagonistic complement factors for a single protein on N. meningitidis rules disease susceptibility. eLife 2014; 3. [PMID: 25534642 PMCID: PMC4273445 DOI: 10.7554/elife.04008] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Accepted: 11/25/2014] [Indexed: 11/13/2022] Open
Abstract
Genome-wide association studies have found variation within the complement factor H gene family links to host susceptibility to meningococcal disease caused by infection with Neisseria meningitidis (Davila et al., 2010). Mechanistic insights have been challenging since variation within this locus is complex and biological roles of the factor H-related proteins, unlike factor H, are incompletely understood. N. meningitidis subverts immune responses by hijacking a host-immune regulator, complement factor H (CFH), to the bacterial surface (Schneider et al., 2006; Madico et al., 2007; Schneider et al., 2009). We demonstrate that complement factor-H related 3 (CFHR3) promotes immune activation by acting as an antagonist of CFH. Conserved sequences between CFH and CFHR3 mean that the bacterium cannot sufficiently distinguish between these two serum proteins to allow it to hijack the regulator alone. The level of protection from complement attack achieved by circulating N. meningitidis therefore depends on the relative levels of CFH and CFHR3 in serum. These data may explain the association between genetic variation in both CFH and CFHR3 and susceptibility to meningococcal disease.
Collapse
Affiliation(s)
- Joseph J E Caesar
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Hayley Lavender
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Philip N Ward
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Rachel M Exley
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Jack Eaton
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Emily Chittock
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Talat H Malik
- Centre for Complement and Inflammation Research, Department of Medicine, Imperial College, London, United Kingdom
| | - Elena Goiecoechea De Jorge
- Centre for Complement and Inflammation Research, Department of Medicine, Imperial College, London, United Kingdom
| | - Matthew C Pickering
- Centre for Complement and Inflammation Research, Department of Medicine, Imperial College, London, United Kingdom
| | - Christoph M Tang
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Susan M Lea
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| |
Collapse
|
6
|
Johnson S, Tan L, van der Veen S, Caesar J, Goicoechea De Jorge E, Harding RJ, Bai X, Exley RM, Ward PN, Ruivo N, Trivedi K, Cumber E, Jones R, Newham L, Staunton D, Ufret-Vincenty R, Borrow R, Pickering MC, Lea SM, Tang CM. Design and evaluation of meningococcal vaccines through structure-based modification of host and pathogen molecules. PLoS Pathog 2012; 8:e1002981. [PMID: 23133374 PMCID: PMC3486911 DOI: 10.1371/journal.ppat.1002981] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Accepted: 09/04/2012] [Indexed: 11/18/2022] Open
Abstract
Neisseria meningitis remains a leading cause of sepsis and meningitis, and vaccines are required to prevent infections by this important human pathogen. Factor H binding protein (fHbp) is a key antigen that elicits protective immunity against the meningococcus and recruits the host complement regulator, fH. As the high affinity interaction between fHbp and fH could impair immune responses, we sought to identify non-functional fHbps that could act as effective immunogens. This was achieved by alanine substitution of fHbps from all three variant groups (V1, V2 and V3 fHbp) of the protein; while some residues affected fH binding in each variant group, the distribution of key amino underlying the interaction with fH differed between the V1, V2 and V3 proteins. The atomic structure of V3 fHbp in complex with fH and of the C-terminal barrel of V2 fHbp provide explanations to the differences in the precise nature of their interactions with fH, and the instability of the V2 protein. To develop transgenic models to assess the efficacy of non-functional fHbps, we determined the structural basis of the low level of interaction between fHbp and murine fH; in addition to changes in amino acids in the fHbp binding site, murine fH has a distinct conformation compared with the human protein that would sterically inhibit binding to fHbp. Non-functional V1 fHbps were further characterised by binding and structural studies, and shown in non-transgenic and transgenic mice (expressing chimeric fH that binds fHbp and precisely regulates complement system) to retain their immunogenicity. Our findings provide a catalogue of non-functional fHbps from all variant groups that can be included in new generation meningococcal vaccines, and establish proof-in-principle for clinical studies to compare their efficacy with wild-type fHbps. Vaccines are currently available against several serogroups of Neisseria meningitidis. However broadly effective serogroup B vaccines are still required as capsule-based approaches cannot be implemented with this serogroup because of the risks of auto-immunity. As a result, vaccines based on proteins in the bacterial outer membrane are being developed. Factor H binding protein (fHbp) is an important meningococcal immunogen which is able to bind the human complement regulator factor H (fH) at high affinity; this interaction could impair the efficacy of fHbp-based vaccines. Here we perform structure:function analyses to define non-functional fHbps and to explain the basis for the host specificity of the fHbp:fH interaction. The vaccine candidacy of non-functional fHbps was compared with wild-type proteins in a relevant transgenic model. These findings should allow the design and evaluation of future fHbp vaccines against this important human pathogen.
Collapse
Affiliation(s)
- Steven Johnson
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Lionel Tan
- Centre for Molecular Microbiology and Infection, Imperial College, London, United Kingdom
| | - Stijn van der Veen
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Joseph Caesar
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Elena Goicoechea De Jorge
- Centre for Complement and Inflammation Research (CCIR), Department of Medicine, Imperial College, London, United Kingdom
| | - Rachel J. Harding
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Xilian Bai
- Vaccine Evaluation Unit, Public Health Laboratory, Manchester Medical Microbiology Partnership, Manchester, United Kingdom
| | - Rachel M. Exley
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Philip N. Ward
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Nicola Ruivo
- Centre for Molecular Microbiology and Infection, Imperial College, London, United Kingdom
| | - Kaushali Trivedi
- Centre for Molecular Microbiology and Infection, Imperial College, London, United Kingdom
| | - Elspeth Cumber
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Rhian Jones
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Luke Newham
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - David Staunton
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Rafael Ufret-Vincenty
- Department of Ophthalmology, UT Southwestern Medical Center, Dallas, Texas, United States of America
| | - Ray Borrow
- Vaccine Evaluation Unit, Public Health Laboratory, Manchester Medical Microbiology Partnership, Manchester, United Kingdom
| | - Matthew C. Pickering
- Centre for Complement and Inflammation Research (CCIR), Department of Medicine, Imperial College, London, United Kingdom
- * E-mail: (MCP); (SML); (CMT)
| | - Susan M. Lea
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
- * E-mail: (MCP); (SML); (CMT)
| | - Christoph M. Tang
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
- Centre for Molecular Microbiology and Infection, Imperial College, London, United Kingdom
- * E-mail: (MCP); (SML); (CMT)
| |
Collapse
|
7
|
Donoso LA, Vrabec T, Kuivaniemi H. The role of complement Factor H in age-related macular degeneration: a review. Surv Ophthalmol 2010; 55:227-46. [PMID: 20385334 DOI: 10.1016/j.survophthal.2009.11.001] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2009] [Revised: 10/20/2009] [Accepted: 11/03/2009] [Indexed: 11/19/2022]
Abstract
Factor H is a 155kDa sialic acid containing glycoprotein that plays an integral role in the regulation of the complement-mediated immune system that is involved in microbial defense, immune complex processing, and programmed cell death. These events take place primarily in fluid phase and on the cell surface and are particularly important in the context of distinguishing self from non-self. Activation of the complement system occurs within seconds and results in a proteolytic cascade eventually forming the membrane attack complex leading to cell lysis. Factor H protects host cells from injury resulting from unrestrained complement activation. Mutations and SNPs (single nucleotide polymorphisms) in Factor H have been implicated in a variety of human conditions including age-related macular degeneration (AMD), atypical hemolytic uremic syndrome, and membranoproliferative glomuleronephritis type II or dense deposit disease. It should not be surprising that these seemingly unrelated diseases involving mutations in Factor H may share common features. Because the immune process involves, in part, an inflammatory response and common or similar surface antigens, it is also not unexpected to observe features of inflammation, including deposition of bioactive complement fragments such as C3a and C5a, a cellular influx of immune related cells such as lymphocytes, and the potential for multiple organ involvement. We review recent developments in molecular genetics; SNPs, including Y402H; the three-dimensional structure; and mass spectroscopy of Factor H as it relates to the pathogenesis of eye disease. In addition, we discuss the concepts of molecular mimicry, sequestered or hidden antigens, and antigenic cross reactivity, and propose that AMD should not simply be considered to be an eye disease, but rather a systemic vascular disease where the eye has the ability to self regulate a local immune response. Identification of the initial event or inciting antigen has yet to be determined and will significantly advance the understanding of the pathogenesis of AMD.
Collapse
Affiliation(s)
- Larry A Donoso
- The Philadelphia Retina Endowment Fund, The Eye Research Institute, Philadelphia, PA, USA.
| | | | | |
Collapse
|
8
|
Roversi P, Johnson S, Lea SM. With phases: how two wrongs can sometimes make a right. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2010; 66:420-5. [PMID: 20382995 PMCID: PMC2852306 DOI: 10.1107/s0907444909048112] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/15/2009] [Accepted: 11/12/2009] [Indexed: 11/10/2022]
Abstract
In isolation, both weak isomorphous/anomalous difference signals from heavy-atom derivatization and phases from partial molecular-replacement solutions for a subset of the asymmetric unit often fall short of producing interpretable electron-density maps. Phases generated from very partial molecular-replacement models (if generated carefully) can be used to reliably locate heavy-atom sites, even if the signal is not sufficiently strong to allow robust finding of the sites using Patterson interpretation or direct methods. Additional advantages are that using molecular-replacement phases to define the heavy-atom substructure avoids the need for subsequent hand determination and/or origin-choice reconciliation and that the partial model can be used to aid the mask determination during solvent flattening. Two case studies are presented in which it was only by combining experimental and molecular-replacement phasing approaches that the crystal structures could be determined.
Collapse
Affiliation(s)
- Pietro Roversi
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, England
| | | | | |
Collapse
|
9
|
Schneider MC, Prosser BE, Caesar JJE, Kugelberg E, Li S, Zhang Q, Quoraishi S, Lovett JE, Deane JE, Sim RB, Roversi P, Johnson S, Tang CM, Lea SM. Neisseria meningitidis recruits factor H using protein mimicry of host carbohydrates. Nature 2009; 458:890-3. [PMID: 19225461 PMCID: PMC2670278 DOI: 10.1038/nature07769] [Citation(s) in RCA: 261] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2008] [Accepted: 01/12/2009] [Indexed: 11/08/2022]
Abstract
The complement system is an essential component of the innate and acquired immune system, and consists of a series of proteolytic cascades that are initiated by the presence of microorganisms. In health, activation of complement is precisely controlled through membrane-bound and soluble plasma-regulatory proteins including complement factor H (fH; ref. 2), a 155 kDa protein composed of 20 domains (termed complement control protein repeats). Many pathogens have evolved the ability to avoid immune-killing by recruiting host complement regulators and several pathogens have adapted to avoid complement-mediated killing by sequestering fH to their surface. Here we present the structure of a complement regulator in complex with its pathogen surface-protein ligand. This reveals how the important human pathogen Neisseria meningitidis subverts immune responses by mimicking the host, using protein instead of charged-carbohydrate chemistry to recruit the host complement regulator, fH. The structure also indicates the molecular basis of the host-specificity of the interaction between fH and the meningococcus, and informs attempts to develop novel therapeutics and vaccines.
Collapse
Affiliation(s)
- Muriel C Schneider
- Centre for Molecular Microbiology and Infection, Imperial College, London SW7 2AZ, UK
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Hakobyan S, Harris CL, van den Berg CW, Fernandez-Alonso MC, de Jorge EG, de Cordoba SR, Rivas G, Mangione P, Pepys MB, Morgan BP. Complement factor H binds to denatured rather than to native pentameric C-reactive protein. J Biol Chem 2008; 283:30451-60. [PMID: 18786923 PMCID: PMC2662140 DOI: 10.1074/jbc.m803648200] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2008] [Revised: 08/20/2008] [Indexed: 11/06/2022] Open
Abstract
Binding of the complement regulatory protein, factor H, to C-reactive protein has been reported and implicated as the biological basis for association of the H402 polymorphic variant of factor H with macular degeneration. Published studies utilize solid-phase or fluid-phase binding assays to show that the factor H Y402 variant binds C-reactive protein more strongly than H402. Diminished binding of H402 variant to C-reactive protein in retinal drusen is posited to permit increased complement activation, driving inflammation and pathology. We used well validated native human C-reactive protein and pure factor H Y402H variants to test interactions. When factor H variants were incubated with C-reactive protein in the fluid phase at physiological concentrations, no association occurred. When C-reactive protein was immobilized on plastic, either non-specifically by adsorption in the presence of Ca(2+) to maintain its native fold and pentameric subunit assembly or by specific Ca(2+)-dependent binding to immobilized natural ligands, no specific binding of either factor H variant from the fluid phase was observed. In contrast, both factor H variants reproducibly bound to C-reactive protein immobilized in the absence of Ca(2+), conditions that destabilize the native fold and pentameric assembly. Both factor H variants strongly bound C-reactive protein that was denatured by heat treatment before immobilization, confirming interaction with denatured but not native C-reactive protein. We conclude that the reported binding of factor H to C-reactive protein results from denaturation of the C-reactive protein during immobilization. Differential binding to C-reactive protein, thus, does not explain association of the Y402H polymorphism with macular degeneration.
Collapse
Affiliation(s)
- Svetlana Hakobyan
- Department of Medical Biochemistry and Immunology and Pharmacology, School of Medicine, Cardiff University, Cardiff CF14 4XN, UK
| | | | | | | | | | | | | | | | | | | |
Collapse
|
11
|
Barlow PN, Hageman GS, Lea SM. Complement factor H: using atomic resolution structure to illuminate disease mechanisms. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008; 632:117-142. [PMID: 19025119 PMCID: PMC4863441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Complement Factor H has recently come to the fore with variant forms implicated in a range of serious disease states. This review aims to bring together recent data concerning the structure and biological activity of this molecule to highlight the way in which a molecular understanding of function may open novel therapeutic possibilities. In particular we examine the evidence for and against the hypothesis that sequence variations in factor H may predispose to disease if they perturb its ability to recognise and respond appropriately to polyanionic carbohydrates on host surfaces that require protection from complement-mediated damage.
Collapse
Affiliation(s)
- Paul N. Barlow
- Schools of Chemistry and Biological Sciences, Joseph Black Chemistry Building, University of Edinburgh, Edinburgh EH9 2PB, UK
| | - Gregory S. Hageman
- Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, IA, USA
| | - Susan M. Lea
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK
| |
Collapse
|
12
|
Prosser BE, Johnson S, Roversi P, Herbert AP, Blaum BS, Tyrrell J, Jowitt TA, Clark SJ, Tarelli E, Uhrín D, Barlow PN, Sim RB, Day AJ, Lea SM. Structural basis for complement factor H linked age-related macular degeneration. J Exp Med 2007; 204:2277-83. [PMID: 17893204 PMCID: PMC2118454 DOI: 10.1084/jem.20071069] [Citation(s) in RCA: 150] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2007] [Accepted: 08/31/2007] [Indexed: 11/04/2022] Open
Abstract
Nearly 50 million people worldwide suffer from age-related macular degeneration (AMD), which causes severe loss of central vision. A single-nucleotide polymorphism in the gene for the complement regulator factor H (FH), which causes a Tyr-to-His substitution at position 402, is linked to approximately 50% of attributable risks for AMD. We present the crystal structure of the region of FH containing the polymorphic amino acid His402 in complex with an analogue of the glycosaminoglycans (GAGs) that localize the complement regulator on the cell surface. The structure demonstrates direct coordination of ligand by the disease-associated polymorphic residue, providing a molecular explanation of the genetic observation. This glycan-binding site occupies the center of an extended interaction groove on the regulator's surface, implying multivalent binding of sulfated GAGs. This finding is confirmed by structure-based site-directed mutagenesis, nuclear magnetic resonance-monitored binding experiments performed for both H402 and Y402 variants with this and another model GAG, and analysis of an extended GAG-FH complex.
Collapse
Affiliation(s)
- Beverly E Prosser
- Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE, England, UK
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|