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Murugaiah V, Varghese PM, Beirag N, DeCordova S, Sim RB, Kishore U. Complement Proteins as Soluble Pattern Recognition Receptors for Pathogenic Viruses. Viruses 2021; 13:v13050824. [PMID: 34063241 PMCID: PMC8147407 DOI: 10.3390/v13050824] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 04/28/2021] [Indexed: 12/11/2022] Open
Abstract
The complement system represents a crucial part of innate immunity. It contains a diverse range of soluble activators, membrane-bound receptors, and regulators. Its principal function is to eliminate pathogens via activation of three distinct pathways: classical, alternative, and lectin. In the case of viruses, the complement activation results in effector functions such as virion opsonisation by complement components, phagocytosis induction, virolysis by the membrane attack complex, and promotion of immune responses through anaphylatoxins and chemotactic factors. Recent studies have shown that the addition of individual complement components can neutralise viruses without requiring the activation of the complement cascade. While the complement-mediated effector functions can neutralise a diverse range of viruses, numerous viruses have evolved mechanisms to subvert complement recognition/activation by encoding several proteins that inhibit the complement system, contributing to viral survival and pathogenesis. This review focuses on these complement-dependent and -independent interactions of complement components (especially C1q, C4b-binding protein, properdin, factor H, Mannose-binding lectin, and Ficolins) with several viruses and their consequences.
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Affiliation(s)
- Valarmathy Murugaiah
- Biosciences, College of Health, Medicine and Life Sciences, Brunel University London, Uxbridge UB8 3PH, UK; (V.M.); (P.M.V.); (N.B.); (S.D.)
| | - Praveen M. Varghese
- Biosciences, College of Health, Medicine and Life Sciences, Brunel University London, Uxbridge UB8 3PH, UK; (V.M.); (P.M.V.); (N.B.); (S.D.)
| | - Nazar Beirag
- Biosciences, College of Health, Medicine and Life Sciences, Brunel University London, Uxbridge UB8 3PH, UK; (V.M.); (P.M.V.); (N.B.); (S.D.)
| | - Syreeta DeCordova
- Biosciences, College of Health, Medicine and Life Sciences, Brunel University London, Uxbridge UB8 3PH, UK; (V.M.); (P.M.V.); (N.B.); (S.D.)
| | - Robert B. Sim
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK;
| | - Uday Kishore
- Biosciences, College of Health, Medicine and Life Sciences, Brunel University London, Uxbridge UB8 3PH, UK; (V.M.); (P.M.V.); (N.B.); (S.D.)
- Correspondence: or
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2
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Sinha A, Singh AK, Kadni TS, Mullick J, Sahu A. Virus-Encoded Complement Regulators: Current Status. Viruses 2021; 13:v13020208. [PMID: 33573085 PMCID: PMC7912105 DOI: 10.3390/v13020208] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2020] [Revised: 01/21/2021] [Accepted: 01/22/2021] [Indexed: 11/29/2022] Open
Abstract
Viruses require a host for replication and survival and hence are subjected to host immunological pressures. The complement system, a crucial first response of the host immune system, is effective in targeting viruses and virus-infected cells, and boosting the antiviral innate and acquired immune responses. Thus, the system imposes a strong selection pressure on viruses. Consequently, viruses have evolved multiple countermeasures against host complement. A major mechanism employed by viruses to subvert the complement system is encoding proteins that target complement. Since viruses have limited genome size, most of these proteins are multifunctional in nature. In this review, we provide up to date information on the structure and complement regulatory functions of various viral proteins.
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Affiliation(s)
- Anwesha Sinha
- Complement Biology Laboratory, National Centre for Cell Science, S. P. Pune University Campus, Ganeskhind, Pune 411007, India; (A.S.); (A.K.S.); (T.S.K.)
| | - Anup Kumar Singh
- Complement Biology Laboratory, National Centre for Cell Science, S. P. Pune University Campus, Ganeskhind, Pune 411007, India; (A.S.); (A.K.S.); (T.S.K.)
| | - Trupti Satish Kadni
- Complement Biology Laboratory, National Centre for Cell Science, S. P. Pune University Campus, Ganeskhind, Pune 411007, India; (A.S.); (A.K.S.); (T.S.K.)
| | - Jayati Mullick
- Polio Virology Group, Microbial Containment Complex, ICMR-National Institute of Virology, Pune 411021, India;
| | - Arvind Sahu
- Complement Biology Laboratory, National Centre for Cell Science, S. P. Pune University Campus, Ganeskhind, Pune 411007, India; (A.S.); (A.K.S.); (T.S.K.)
- Correspondence: ; Tel.: +91-20-2570-8083; Fax: +91-20-2569-2259
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3
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Agrawal P, Sharma S, Pal P, Ojha H, Mullick J, Sahu A. The imitation game: a viral strategy to subvert the complement system. FEBS Lett 2020; 594:2518-2542. [DOI: 10.1002/1873-3468.13856] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 03/10/2020] [Accepted: 05/23/2020] [Indexed: 11/09/2022]
Affiliation(s)
- Palak Agrawal
- Complement Biology Laboratory National Centre for Cell Science S. P. Pune University Campus Ganeshkhind Pune 411007 India
| | - Samriddhi Sharma
- Complement Biology Laboratory National Centre for Cell Science S. P. Pune University Campus Ganeshkhind Pune 411007 India
| | - Pradipta Pal
- Complement Biology Laboratory National Centre for Cell Science S. P. Pune University Campus Ganeshkhind Pune 411007 India
| | - Hina Ojha
- Complement Biology Laboratory National Centre for Cell Science S. P. Pune University Campus Ganeshkhind Pune 411007 India
| | - Jayati Mullick
- Microbial Containment Complex ICMR‐National Institute of Virology Pune 411021 India
| | - Arvind Sahu
- Complement Biology Laboratory National Centre for Cell Science S. P. Pune University Campus Ganeshkhind Pune 411007 India
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Maloney BE, Perera KD, Saunders DRD, Shadipeni N, Fleming SD. Interactions of viruses and the humoral innate immune response. Clin Immunol 2020; 212:108351. [PMID: 32028020 DOI: 10.1016/j.clim.2020.108351] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 02/01/2020] [Accepted: 02/01/2020] [Indexed: 12/13/2022]
Abstract
The innate immune response is crucial for defense against virus infections where the complement system, coagulation cascade and natural antibodies play key roles. These immune components are interconnected in an intricate network and are tightly regulated to maintain homeostasis and avoid uncontrolled immune responses. Many viruses in turn have evolved to modulate these interactions through various strategies to evade innate immune activation. This review summarizes the current understanding on viral strategies to inhibit the activation of complement and coagulation cascades, evade natural antibody-mediated clearance and utilize complement regulatory mechanisms to their advantage.
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Affiliation(s)
- Bailey E Maloney
- Department of Diagnostic Medicine and Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA
| | - Krishani Dinali Perera
- Department of Diagnostic Medicine and Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA
| | - Danielle R D Saunders
- Department of Diagnostic Medicine and Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA
| | - Naemi Shadipeni
- Department of Diagnostic Medicine and Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA
| | - Sherry D Fleming
- Division of Biology, Kansas State University, Manhattan, KS, USA.
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5
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Shende R, Wong SSW, Rapole S, Beau R, Ibrahim-Granet O, Monod M, Gührs KH, Pal JK, Latgé JP, Madan T, Aimanianda V, Sahu A. Aspergillus fumigatus conidial metalloprotease Mep1p cleaves host complement proteins. J Biol Chem 2018; 293:15538-15555. [PMID: 30139746 PMCID: PMC6177592 DOI: 10.1074/jbc.ra117.001476] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Revised: 08/02/2018] [Indexed: 12/30/2022] Open
Abstract
Innate immunity in animals including humans encompasses the complement system, which is considered an important host defense mechanism against Aspergillus fumigatus, one of the most ubiquitous opportunistic human fungal pathogens. Previously, it has been shown that the alkaline protease Alp1p secreted from A. fumigatus mycelia degrades the complement components C3, C4, and C5. However, it remains unclear how the fungal spores (i.e. conidia) defend themselves against the activities of the complement system immediately after inhalation into the lung. Here, we show that A. fumigatus conidia contain a metalloprotease Mep1p, which is released upon conidial contact with collagen and inactivates all three complement pathways. In particular, Mep1p efficiently inactivated the major complement components C3, C4, and C5 and their activation products (C3a, C4a, and C5a) as well as the pattern-recognition molecules MBL and ficolin-1, either by directly cleaving them or by cleaving them to a form that is further broken down by other proteases of the complement system. Moreover, incubation of Mep1p with human serum significantly inhibited the complement hemolytic activity and conidial opsonization by C3b and their subsequent phagocytosis by macrophages. Together, these results indicate that Mep1p associated with and released from A. fumigatus conidia likely facilitates early immune evasion by disarming the complement defense in the human host.
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Affiliation(s)
- Rajashri Shende
- From the Complement Biology Laboratory and
- the Dr. D. Y. Patil Biotechnology and Bioinformatics Institute, Dr. D. Y. Patil Vidyapeeth, Tathawade, Pune-411033, India
| | | | - Srikanth Rapole
- Proteomics Laboratory, National Centre for Cell Science, S. P. Pune University Campus, Ganeshkhind, Pune-411007, India
| | | | | | - Michel Monod
- the Service de Dermatologie, Laboratoire de Mycologie, Centre Hospitalier Universitaire Vaudois, 1011 Lausanne, Switzerland
| | - Karl-Heinz Gührs
- the Leibniz Institute on Aging-Fritz Lipmann Institute, Jena-07745, Germany, and
| | - Jayanta Kumar Pal
- the Dr. D. Y. Patil Biotechnology and Bioinformatics Institute, Dr. D. Y. Patil Vidyapeeth, Tathawade, Pune-411033, India
| | | | - Taruna Madan
- the ICMR-National Institute for Research in Reproductive Health, Parel, Mumbai-400012, India
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6
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Agrawal P, Nawadkar R, Ojha H, Kumar J, Sahu A. Complement Evasion Strategies of Viruses: An Overview. Front Microbiol 2017; 8:1117. [PMID: 28670306 PMCID: PMC5472698 DOI: 10.3389/fmicb.2017.01117] [Citation(s) in RCA: 104] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 05/31/2017] [Indexed: 12/11/2022] Open
Abstract
Being a major first line of immune defense, the complement system keeps a constant vigil against viruses. Its ability to recognize large panoply of viruses and virus-infected cells, and trigger the effector pathways, results in neutralization of viruses and killing of the infected cells. This selection pressure exerted by complement on viruses has made them evolve a multitude of countermeasures. These include targeting the recognition molecules for the avoidance of detection, targeting key enzymes and complexes of the complement pathways like C3 convertases and C5b-9 formation - either by encoding complement regulators or by recruiting membrane-bound and soluble host complement regulators, cleaving complement proteins by encoding protease, and inhibiting the synthesis of complement proteins. Additionally, viruses also exploit the complement system for their own benefit. For example, they use complement receptors as well as membrane regulators for cellular entry as well as their spread. Here, we provide an overview on the complement subversion mechanisms adopted by the members of various viral families including Poxviridae, Herpesviridae, Adenoviridae, Flaviviridae, Retroviridae, Picornaviridae, Astroviridae, Togaviridae, Orthomyxoviridae and Paramyxoviridae.
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Affiliation(s)
- Palak Agrawal
- Complement Biology Laboratory, National Centre for Cell Science, Savitribai Phule Pune UniversityPune, India
| | - Renuka Nawadkar
- Complement Biology Laboratory, National Centre for Cell Science, Savitribai Phule Pune UniversityPune, India
| | - Hina Ojha
- Complement Biology Laboratory, National Centre for Cell Science, Savitribai Phule Pune UniversityPune, India
| | - Jitendra Kumar
- Complement Biology Laboratory, National Centre for Cell Science, Savitribai Phule Pune UniversityPune, India
| | - Arvind Sahu
- Complement Biology Laboratory, National Centre for Cell Science, Savitribai Phule Pune UniversityPune, India
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7
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Abou-El-Hassan H, Zaraket H. Viral-derived complement inhibitors: current status and potential role in immunomodulation. Exp Biol Med (Maywood) 2016; 242:397-410. [PMID: 27798122 DOI: 10.1177/1535370216675772] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The complement system is one of the body's major innate immune defense mechanisms in vertebrates. Its function is to detect foreign bodies and promote their elimination through opsonisation or lysis. Complement proteins play an important role in the immunopathogenesis of several disorders. However, excessive complement activation does not confer more protection but instead leads to several autoimmune and inflammatory diseases. With inappropriate activation of the complement system, activated complement proteins and glycoproteins may damage both healthy and diseased tissues. Development of complement inhibitors represents an effective approach in controlling dysregulated complement activity and reducing disease severity, yet few studies have investigated the nature and role of novel complement inhibitory proteins of viral origin. Viral complement inhibitors have important implications in understanding the importance of complement inhibition and their role as a promising novel therapeutic approach in diseases caused by dysregulated complement function. In this review, we discuss the role and importance of complement inhibitors derived from several viruses in the scope of human inflammatory and autoimmune diseases.
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Affiliation(s)
- Hadi Abou-El-Hassan
- 1 Faculty of Medicine, American University of Beirut Medical Center, Beirut, Lebanon.,2 Center for Infectious Diseases Research, Faculty of Medicine, American University of Beirut, Beirut, Lebanon
| | - Hassan Zaraket
- 2 Center for Infectious Diseases Research, Faculty of Medicine, American University of Beirut, Beirut, Lebanon.,3 Department of Experimental Pathology, Immunology, and Microbiology, Faculty of Medicine, American University of Beirut, Beirut, Lebanon
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8
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Banerjee S, Uppal T, Strahan R, Dabral P, Verma SC. The Modulation of Apoptotic Pathways by Gammaherpesviruses. Front Microbiol 2016; 7:585. [PMID: 27199919 PMCID: PMC4847483 DOI: 10.3389/fmicb.2016.00585] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Accepted: 04/11/2016] [Indexed: 12/11/2022] Open
Abstract
Apoptosis or programmed cell death is a tightly regulated process fundamental for cellular development and elimination of damaged or infected cells during the maintenance of cellular homeostasis. It is also an important cellular defense mechanism against viral invasion. In many instances, abnormal regulation of apoptosis has been associated with a number of diseases, including cancer development. Following infection of host cells, persistent and oncogenic viruses such as the members of the Gammaherpesvirus family employ a number of different mechanisms to avoid the host cell’s “burglar” alarm and to alter the extrinsic and intrinsic apoptotic pathways by either deregulating the expressions of cellular signaling genes or by encoding the viral homologs of cellular genes. In this review, we summarize the recent findings on how gammaherpesviruses inhibit cellular apoptosis via virus-encoded proteins by mediating modification of numerous signal transduction pathways. We also list the key viral anti-apoptotic proteins that could be exploited as effective targets for novel antiviral therapies in order to stimulate apoptosis in different types of cancer cells.
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Affiliation(s)
- Shuvomoy Banerjee
- Amity Institute of Virology and Immunology, Amity University Noida, India
| | - Timsy Uppal
- Department of Microbiology and Immunology, Center for Molecular Medicine, School of Medicine, University of Nevada, Reno Reno, NV, USA
| | - Roxanne Strahan
- Department of Microbiology and Immunology, Center for Molecular Medicine, School of Medicine, University of Nevada, Reno Reno, NV, USA
| | - Prerna Dabral
- Department of Microbiology and Immunology, Center for Molecular Medicine, School of Medicine, University of Nevada, Reno Reno, NV, USA
| | - Subhash C Verma
- Department of Microbiology and Immunology, Center for Molecular Medicine, School of Medicine, University of Nevada, Reno Reno, NV, USA
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9
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Dissection of functional sites in herpesvirus saimiri complement control protein homolog. J Virol 2012; 87:282-95. [PMID: 23077301 DOI: 10.1128/jvi.01867-12] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Herpesvirus saimiri is known to encode a homolog of human complement regulators named complement control protein homolog (CCPH). We have previously reported that this virally encoded inhibitor effectively inactivates complement by supporting factor I-mediated inactivation of complement proteins C3b and C4b (termed cofactor activity), as well as by accelerating the irreversible decay of the classical/lectin and alternative pathway C3 convertases (termed decay-accelerating activity). To fine map its functional sites, in the present study, we have generated a homology model of CCPH and performed substitution mutagenesis of its conserved residues. Functional analyses of 24 substitution mutants of CCPH indicated that (i) amino acids R118 and F144 play a critical role in imparting C3b and C4b cofactor activities, (ii) amino acids R35, K142, and K191 are required for efficient decay of the C3 convertases, (iii) positively charged amino acids of the linker regions, which are dubbed to be critical for functioning in other complement regulators, are not crucial for its function, and (iv) S100K and G110D mutations substantially enhance its decay-accelerating activities without affecting the cofactor activities. Overall, our data point out that ionic interactions form a major component of the binding interface between CCPH and its interacting partners.
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10
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Yadav VN, Pyaram K, Ahmad M, Sahu A. Species selectivity in poxviral complement regulators is dictated by the charge reversal in the central complement control protein modules. THE JOURNAL OF IMMUNOLOGY 2012; 189:1431-9. [PMID: 22732591 DOI: 10.4049/jimmunol.1200946] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Variola and vaccinia viruses, the two most important members of the family Poxviridae, are known to encode homologs of the human complement regulators named smallpox inhibitor of complement enzymes (SPICE) and vaccinia virus complement control protein (VCP), respectively, to subvert the host complement system. Intriguingly, consistent with the host tropism of these viruses, SPICE has been shown to be more human complement-specific than VCP, and in this study we show that VCP is more bovine complement-specific than SPICE. Based on mutagenesis and mechanistic studies, we suggest that the major determinant for the switch in species selectivity of SPICE and VCP is the presence of oppositely charged residues in the central complement control modules, which help enhance their interaction with factor I and C3b, the proteolytically cleaved form of C3. Thus, our results provide a molecular basis for the species selectivity in poxviral complement regulators.
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Affiliation(s)
- Viveka Nand Yadav
- National Centre for Cell Science, Pune University, Ganeshkhind, Pune 411007, India
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11
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Sreejith RK, Suresh CG, Bhosale SH, Bhavnani V, Kumar A, Gaikwad SM, Pal JK. Conformational Transitions of the Catalytic Domain of Heme-Regulated Eukaryotic Initiation Factor 2α Kinase, a Key Translational Regulatory Molecule. J Fluoresc 2011; 22:431-41. [DOI: 10.1007/s10895-011-0976-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2011] [Accepted: 09/13/2011] [Indexed: 01/18/2023]
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12
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Pyaram K, Yadav VN, Reza MJ, Sahu A. Virus–complement interactions: an assiduous struggle for dominance. Future Virol 2010. [DOI: 10.2217/fvl.10.60] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The complement system is a major component of the innate immune system that recognizes invading pathogens and eliminates them by means of an array of effector mechanisms, in addition to using direct lytic destruction. Viruses, in spite of their small size and simple composition, are also deftly recognized and neutralized by the complement system. In turn, as a result of years of coevolution with the host, viruses have developed multiple mechanisms to evade the host complement. These complex interactions between the complement system and viruses have been an area of focus for over three decades. In this article, we provide a broad overview of the field using key examples and up-to-date information on the complement-evasion strategies of viruses.
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Affiliation(s)
- Kalyani Pyaram
- National Centre for Cell Science, Pune University Campus, Ganeshkhind, Pune 411007, India
| | - Viveka Nand Yadav
- National Centre for Cell Science, Pune University Campus, Ganeshkhind, Pune 411007, India
| | - Malik Johid Reza
- National Centre for Cell Science, Pune University Campus, Ganeshkhind, Pune 411007, India
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13
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Ahmad M, Raut S, Pyaram K, Kamble A, Mullick J, Sahu A. Domain Swapping Reveals Complement Control Protein Modules Critical for Imparting Cofactor and Decay-Accelerating Activities in Vaccinia Virus Complement Control Protein. THE JOURNAL OF IMMUNOLOGY 2010; 185:6128-37. [DOI: 10.4049/jimmunol.1001617] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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14
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Steer B, Adler B, Jonjic S, Stewart JP, Adler H. A gammaherpesvirus complement regulatory protein promotes initiation of infection by activation of protein kinase Akt/PKB. PLoS One 2010; 5:e11672. [PMID: 20657771 PMCID: PMC2908122 DOI: 10.1371/journal.pone.0011672] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2010] [Accepted: 06/27/2010] [Indexed: 12/22/2022] Open
Abstract
Background Viruses have evolved to evade the host's complement system. The open reading frames 4 (ORF4) of gammaherpesviruses encode homologs of regulators of complement activation (RCA) proteins, which inhibit complement activation at the level of C3 and C4 deposition. Besides complement regulation, these proteins are involved in heparan sulfate and glycosaminoglycan binding, and in case of MHV-68, also in viral DNA synthesis in macrophages. Methodology/Principal Findings Here, we made use of MHV-68 to study the role of ORF4 during infection of fibroblasts. While attachment and penetration of virions lacking the RCA protein were not affected, we observed a delayed delivery of the viral genome to the nucleus of infected cells. Analysis of the phosphorylation status of a variety of kinases revealed a significant reduction in phosphorylation of the protein kinase Akt in cells infected with ORF4 mutant virus, when compared to cells infected with wt virus. Consistent with a role of Akt activation in initial stages of infection, inhibition of Akt signaling in wt virus infected cells resulted in a phenotype resembling the phenotype of the ORF4 mutant virus, and activation of Akt by addition of insulin partially reversed the phenotype of the ORF4 mutant virus. Importantly, the homologous ORF4 of KSHV was able to rescue the phenotype of the MHV-68 ORF4 mutant, indicating that ORF4 is functionally conserved and that ORF4 of KSHV might have a similar function in infection initiation. Conclusions/Significance In summary, our studies demonstrate that ORF4 contributes to efficient infection by activation of the protein kinase Akt and thus reveal a novel function of a gammaherpesvirus RCA protein.
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Affiliation(s)
- Beatrix Steer
- The Institute of Molecular Immunology, Clinical Cooperation Group Hematopoietic Cell Transplantation, Helmholtz Zentrum München - German Research Center for Environmental Health, Munich, Germany
| | - Barbara Adler
- Max von Pettenkofer-Institute, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Stipan Jonjic
- Department of Histology and Embryology, Faculty of Medicine, University of Rijeka, Rijeka, Croatia
| | - James P. Stewart
- Centre for Comparative Infectious Diseases, Department of Medical Microbiology, University of Liverpool, Liverpool, United Kingdom
| | - Heiko Adler
- The Institute of Molecular Immunology, Clinical Cooperation Group Hematopoietic Cell Transplantation, Helmholtz Zentrum München - German Research Center for Environmental Health, Munich, Germany
- * E-mail:
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15
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Kadam AP, Sahu A. Identification of Complin, a novel complement inhibitor that targets complement proteins factor B and C2. THE JOURNAL OF IMMUNOLOGY 2010; 184:7116-24. [PMID: 20483772 DOI: 10.4049/jimmunol.1000200] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Complement factor B (fB) is a key constituent of the alternative pathway (AP). Its central role in causing inflammation and tissue injury through activation of the AP urges the need for its therapeutic targeting. In the current study, we have screened phage-displayed random peptide libraries against fB and identified a novel cyclic hendecapeptide that inhibits activation of fB and the AP. Structure-activity studies revealed that: 1) the cysteine-constrained structure of the peptide is essential for its activity; 2) Ile5, Arg6, Leu7, and Tyr8 contribute significantly to its inhibitory activity; and 3) retro-inverso modification of the peptide results in loss of its activity. Binding studies performed using surface plasmon resonance suggested that the peptide has two binding sites on fB, which are located on the Ba and Bb fragments. Studies on the mechanism of inhibition revealed that the peptide does not block the interaction of fB with the activated form of C3, thereby suggesting that the peptide inhibits fB activation primarily by inhibiting its cleavage by factor D. The peptide showed a weak effect on preformed C3 and C5 convertases. Like inhibition of fB cleavage, the peptide also inhibited C2 cleavage by activated C1s and activation of the classical as well as lectin pathways. Based on its inhibitory activities, we named the peptide Complin.
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Affiliation(s)
- Archana P Kadam
- National Centre for Cell Science, Pune University Campus, Ganeshkhind, Pune, India
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16
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Pyaram K, Kieslich CA, Yadav VN, Morikis D, Sahu A. Influence of electrostatics on the complement regulatory functions of Kaposica, the complement inhibitor of Kaposi's sarcoma-associated herpesvirus. THE JOURNAL OF IMMUNOLOGY 2010; 184:1956-67. [PMID: 20089702 DOI: 10.4049/jimmunol.0903261] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Kaposica, the complement regulator of Kaposi's sarcoma-associated herpesvirus, inhibits complement by supporting factor I-mediated inactivation of the proteolytically activated form of C3 (C3b) and C4 (C4b) (cofactor activity [CFA]) and by accelerating the decay of classical and alternative pathway C3-convertases (decay-accelerating activity [DAA]). Previous data suggested that electrostatic interactions play a critical role in the binding of viral complement regulators to their targets, C3b and C4b. We therefore investigated how electrostatic potential on Kaposica influences its activities. We built a homology structure of Kaposica and calculated the electrostatic potential of the molecule, using the Poisson-Boltzmann equation. Mutants were then designed to alter the overall positive potential of the molecule or of each of its domains and linkers by mutating Lys/Arg to Glu/Gln, and the functional activities of the expressed mutants were analyzed. Our data indicate that 1) positive potential at specific sites and not the overall positive potential on the molecule guides the CFAs and classical pathway DAA; 2) positive potential around the linkers between complement control protein domains (CCPs) 1-2 and 2-3 is more important for DAAs than for CFAs; 3) positive potential in CCP1 is crucial for binding to C3b and C4b, and thereby its functional activities; 4) conversion to negative or enhancement of negative potential for CCPs 2-4 has a marked effect on C3b-linked activities as opposed to C4b-linked activities; and 5) reversal of the electrostatic potential of CCP4 to negative has a differential effect on classical and alternative pathway DAAs. Together, our data provide functional relevance to conservation of positive potential in CCPs 1 and 4 and the linkers of viral complement regulators.
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Affiliation(s)
- Kalyani Pyaram
- National Centre for Cell Science, Pune University Campus, Ganeshkhind, Pune, India
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17
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Conformational characterization of human eukaryotic initiation factor 2α: A single tryptophan protein. Biochem Biophys Res Commun 2009; 390:273-9. [DOI: 10.1016/j.bbrc.2009.09.106] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2009] [Accepted: 09/24/2009] [Indexed: 11/22/2022]
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18
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Mapping of functional domains in herpesvirus saimiri complement control protein homolog: complement control protein domain 2 is the smallest structural unit displaying cofactor and decay-accelerating activities. J Virol 2009; 83:10299-304. [PMID: 19640995 DOI: 10.1128/jvi.00217-09] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Herpesvirus saimiri encodes a functional homolog of human regulator-of-complement-activation proteins named CCPH that inactivates complement by accelerating the decay of C3 convertases and by serving as a cofactor in factor I-mediated inactivation of their subunits C3b and C4b. Here, we map the functional domains of CCPH. We demonstrate that short consensus repeat 2 (SCR2) is the minimum domain essential for classical/lectin pathway C3 convertase decay-accelerating activity as well as for factor I cofactor activity for C3b and C4b. Thus, CCPH is the first example wherein a single SCR domain has been shown to display complement regulatory functions.
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19
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Avirutnan P, Mehlhop E, Diamond MS. Complement and its role in protection and pathogenesis of flavivirus infections. Vaccine 2009; 26 Suppl 8:I100-7. [PMID: 19388173 PMCID: PMC2768071 DOI: 10.1016/j.vaccine.2008.11.061] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The complement system is a family of serum and cell surface proteins that recognize pathogen-associated molecular patterns, altered-self ligands, and immune complexes. Activation of the complement cascade triggers several antiviral functions including pathogen opsonization and/or lysis, and priming of adaptive immune responses. In this review, we will examine the role of complement activation in protection and/or pathogenesis against infection by Flaviviruses, with an emphasis on experiments with West Nile and Dengue viruses.
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Affiliation(s)
- Panisadee Avirutnan
- Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, United States
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Okroj M, Mark L, Stokowska A, Wong SW, Rose N, Blackbourn DJ, Villoutreix BO, Spiller OB, Blom AM. Characterization of the complement inhibitory function of rhesus rhadinovirus complement control protein (RCP). J Biol Chem 2008; 284:505-514. [PMID: 18990693 DOI: 10.1074/jbc.m806669200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Rhesus rhadinovirus (RRV) is currently the closest known, fully sequenced homolog of human Kaposi sarcoma-associated herpesvirus. Both these viruses encode complement inhibitors as follows: Kaposi sarcoma-associated herpesvirus-complement control protein (KCP) and RRV-complement control protein (RCP). Previously we characterized in detail the functional properties of KCP as a complement inhibitor. Here, we performed comparative analyses for two variants of RCP protein, encoded by RRV strains H26-95 and 17577. Both RCP variants and KCP inhibited human and rhesus complement when tested in hemolytic assays measuring all steps of activation via the classical and the alternative pathway. RCP variants from both RRV strains supported C3b and C4b degradation by factor I and decay acceleration of the classical C3 convertase, similar to KCP. Additionally, the 17577 RCP variant accelerated decay of the alternative C3 convertase, which was not seen for KCP. In contrast to KCP, RCP showed no affinity to heparin and is the first described complement inhibitor in which the binding site for C3b/C4b does not interact with heparin. Molecular modeling shows a structural disruption in the region of RCP that corresponds to the KCP-heparin-binding site. This makes RRV a superior model for future in vivo investigations of complement evasion, as RCP does not play a supportive role in viral attachment as KCP does.
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Affiliation(s)
- Marcin Okroj
- Department of Laboratory Medicine, Lund University, University Hospital Malmo¨, Malmo¨ S-20502, Sweden, the Vaccine and Gene Therapy Institute, Oregon Health and Science University, Beaverton, Oregon 97006, the National Institute for Biological Standards and Control, Herts EN6 3QG, United Kingdom, the Cancer Research UK Institute for Cancer Studies, University of Birmingham, Birmingham B15 2TT, United Kingdom, INSERM MTi, University Paris Diderot, Paris 75013, France, and the Department of Child Health, Cardiff University, Wales School of Medicine, Cardiff CF14 4XN, United Kingdom
| | - Linda Mark
- Department of Laboratory Medicine, Lund University, University Hospital Malmo¨, Malmo¨ S-20502, Sweden, the Vaccine and Gene Therapy Institute, Oregon Health and Science University, Beaverton, Oregon 97006, the National Institute for Biological Standards and Control, Herts EN6 3QG, United Kingdom, the Cancer Research UK Institute for Cancer Studies, University of Birmingham, Birmingham B15 2TT, United Kingdom, INSERM MTi, University Paris Diderot, Paris 75013, France, and the Department of Child Health, Cardiff University, Wales School of Medicine, Cardiff CF14 4XN, United Kingdom
| | - Anna Stokowska
- Department of Laboratory Medicine, Lund University, University Hospital Malmo¨, Malmo¨ S-20502, Sweden, the Vaccine and Gene Therapy Institute, Oregon Health and Science University, Beaverton, Oregon 97006, the National Institute for Biological Standards and Control, Herts EN6 3QG, United Kingdom, the Cancer Research UK Institute for Cancer Studies, University of Birmingham, Birmingham B15 2TT, United Kingdom, INSERM MTi, University Paris Diderot, Paris 75013, France, and the Department of Child Health, Cardiff University, Wales School of Medicine, Cardiff CF14 4XN, United Kingdom
| | - Scott W Wong
- Department of Laboratory Medicine, Lund University, University Hospital Malmo¨, Malmo¨ S-20502, Sweden, the Vaccine and Gene Therapy Institute, Oregon Health and Science University, Beaverton, Oregon 97006, the National Institute for Biological Standards and Control, Herts EN6 3QG, United Kingdom, the Cancer Research UK Institute for Cancer Studies, University of Birmingham, Birmingham B15 2TT, United Kingdom, INSERM MTi, University Paris Diderot, Paris 75013, France, and the Department of Child Health, Cardiff University, Wales School of Medicine, Cardiff CF14 4XN, United Kingdom
| | - Nicola Rose
- Department of Laboratory Medicine, Lund University, University Hospital Malmo¨, Malmo¨ S-20502, Sweden, the Vaccine and Gene Therapy Institute, Oregon Health and Science University, Beaverton, Oregon 97006, the National Institute for Biological Standards and Control, Herts EN6 3QG, United Kingdom, the Cancer Research UK Institute for Cancer Studies, University of Birmingham, Birmingham B15 2TT, United Kingdom, INSERM MTi, University Paris Diderot, Paris 75013, France, and the Department of Child Health, Cardiff University, Wales School of Medicine, Cardiff CF14 4XN, United Kingdom
| | - David J Blackbourn
- Department of Laboratory Medicine, Lund University, University Hospital Malmo¨, Malmo¨ S-20502, Sweden, the Vaccine and Gene Therapy Institute, Oregon Health and Science University, Beaverton, Oregon 97006, the National Institute for Biological Standards and Control, Herts EN6 3QG, United Kingdom, the Cancer Research UK Institute for Cancer Studies, University of Birmingham, Birmingham B15 2TT, United Kingdom, INSERM MTi, University Paris Diderot, Paris 75013, France, and the Department of Child Health, Cardiff University, Wales School of Medicine, Cardiff CF14 4XN, United Kingdom
| | - Bruno O Villoutreix
- Department of Laboratory Medicine, Lund University, University Hospital Malmo¨, Malmo¨ S-20502, Sweden, the Vaccine and Gene Therapy Institute, Oregon Health and Science University, Beaverton, Oregon 97006, the National Institute for Biological Standards and Control, Herts EN6 3QG, United Kingdom, the Cancer Research UK Institute for Cancer Studies, University of Birmingham, Birmingham B15 2TT, United Kingdom, INSERM MTi, University Paris Diderot, Paris 75013, France, and the Department of Child Health, Cardiff University, Wales School of Medicine, Cardiff CF14 4XN, United Kingdom
| | - O Brad Spiller
- Department of Laboratory Medicine, Lund University, University Hospital Malmo¨, Malmo¨ S-20502, Sweden, the Vaccine and Gene Therapy Institute, Oregon Health and Science University, Beaverton, Oregon 97006, the National Institute for Biological Standards and Control, Herts EN6 3QG, United Kingdom, the Cancer Research UK Institute for Cancer Studies, University of Birmingham, Birmingham B15 2TT, United Kingdom, INSERM MTi, University Paris Diderot, Paris 75013, France, and the Department of Child Health, Cardiff University, Wales School of Medicine, Cardiff CF14 4XN, United Kingdom
| | - Anna M Blom
- Department of Laboratory Medicine, Lund University, University Hospital Malmo¨, Malmo¨ S-20502, Sweden, the Vaccine and Gene Therapy Institute, Oregon Health and Science University, Beaverton, Oregon 97006, the National Institute for Biological Standards and Control, Herts EN6 3QG, United Kingdom, the Cancer Research UK Institute for Cancer Studies, University of Birmingham, Birmingham B15 2TT, United Kingdom, INSERM MTi, University Paris Diderot, Paris 75013, France, and the Department of Child Health, Cardiff University, Wales School of Medicine, Cardiff CF14 4XN, United Kingdom.
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21
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Cummings KL, Waggoner SN, Tacke R, Hahn YS. Role of complement in immune regulation and its exploitation by virus. Viral Immunol 2008; 20:505-24. [PMID: 18158725 DOI: 10.1089/vim.2007.0061] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Complement is activated during the early phase of viral infection and promotes destruction of virus particles as well as the initiation of inflammatory responses. Recently, complement and complement receptors have been reported to play an important role in the regulation of innate as well as adaptive immune responses during infection. The regulation of host immune responses by complement involves modulation of dendritic cell activity in addition to direct effects on T-cell function. Intriguingly, many viruses encode homologs of complement regulatory molecules or proteins that interact with complement receptors on antigen-presenting cells and lymphocytes. The evolution of viral mechanisms to alter complement function may augment pathogen persistence and limit immune-mediated tissue destruction. These observations suggest that complement may play an important role in both innate and adaptive immune responses to infection as well as virus-mediated modulation of host immunity.
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Affiliation(s)
- Kara L Cummings
- Beirne Carter Center for Immunology Research and Department of Microbiology, University of Virginia, Charlottesville, Virginia
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22
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Identification of hot spots in the variola virus complement inhibitor (SPICE) for human complement regulation. J Virol 2008; 82:3283-94. [PMID: 18216095 DOI: 10.1128/jvi.01935-07] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Variola virus, the causative agent of smallpox, encodes a soluble complement regulator named SPICE. Previously, SPICE has been shown to be much more potent in inactivating human complement than the vaccinia virus complement control protein (VCP), although they differ only in 11 amino acid residues. In the present study, we have expressed SPICE, VCP, and mutants of VCP by substituting each or more of the 11 non-variant VCP residues with the corresponding residue of SPICE to identify hot spots that impart functional advantage to SPICE over VCP. Our data indicate that (i) SPICE is approximately 90-fold more potent than VCP in inactivating human C3b, and the residues Y98, Y103, K108 and K120 are predominantly responsible for its enhanced activity; (ii) SPICE is 5.4-fold more potent in inactivating human C4b, and residues Y98, Y103, K108, K120 and L193 mainly dictate this increase; (iii) the classical pathway decay-accelerating activity of activity is only twofold higher than that of VCP, and the 11 mutations in SPICE do not significantly affect this activity; (iv) SPICE possesses significantly greater binding ability to human C3b compared to VCP, although its binding to human C4b is lower than that of VCP; (v) residue N144 is largely responsible for the increased binding of SPICE to human C3b; and (vi) the human specificity of SPICE is dictated primarily by residues Y98, Y103, K108, and K120 since these are enough to formulate VCP as potent as SPICE. Together, these results suggest that principally 4 of the 11 residues that differ between SPICE and VCP partake in its enhanced function against human complement.
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Blom AM, Mark L, Spiller OB. Viral Heparin-Binding Complement Inhibitors – A Recurring Theme. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2007; 598:105-25. [PMID: 17892208 DOI: 10.1007/978-0-387-71767-8_9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Anna M Blom
- Lund University, Department of Laboratory Medicine, The Wallenberg Laboratory, 4th floor, Malmö University Hospital, entrance 46, S-205 02 Malmö, Sweden
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Kuttner-Kondo L, Hourcade DE, Anderson VE, Muqim N, Mitchell L, Soares DC, Barlow PN, Medof ME. Structure-based mapping of DAF active site residues that accelerate the decay of C3 convertases. J Biol Chem 2007; 282:18552-18562. [PMID: 17395591 DOI: 10.1074/jbc.m611650200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Focused complement activation on foreign targets depends on regulatory proteins that decay the bimolecular C3 convertases. Although this process is central to complement control, how the convertases engage and disassemble is not established. The second and third complement control protein (CCP) modules of the cell surface regulator, decay-accelerating factor (DAF, CD55), comprise the simplest structure mediating this activity. Positioning the functional effects of 31 substitution mutants of DAF CCP2 to -4 on partial structures was previously reported. In light of the high resolution crystal structure of the DAF four-CCP functional region, we now reexamine the effects of these and 40 additional mutations. Moreover, we map six monoclonal antibody epitopes and overlap their effects with those of the amino acid substitutions. The data indicate that the interaction of DAF with the convertases is mediated predominantly by two patches approximately 13 A apart, one centered around Arg69 and Arg96 on CCP2 and the other around Phe148 and Leu171 on CCP3. These patches on the same face of the adjacent modules bracket an intermodular linker of critical length (16 A.) Although the key DAF residues in these patches are present or there are conservative substitutions in all other C3 convertase regulators that mediate decay acceleration and/or provide factor I-cofactor activity, the linker region is highly conserved only in the former. Intra-CCP regions also differ. Linker region comparisons suggest that the active CCPs of the decay accelerators are extended, whereas those of the cofactors are tilted. Intra-CCP comparisons suggest that the two classes of regulators bind different regions on their respective ligands.
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Affiliation(s)
- Lisa Kuttner-Kondo
- Institute of Pathology, Case Western Reserve University, Cleveland, Ohio 44106
| | - Dennis E Hourcade
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Vernon E Anderson
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106
| | - Nasima Muqim
- Institute of Pathology, Case Western Reserve University, Cleveland, Ohio 44106
| | - Lynne Mitchell
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Dinesh C Soares
- Institute of Structural and Molecular Biology and School of Chemistry, University of Edinburgh, Edinburgh EH9 3JJ, Scotland, United Kingdom
| | - Paul N Barlow
- Institute of Structural and Molecular Biology and School of Chemistry, University of Edinburgh, Edinburgh EH9 3JJ, Scotland, United Kingdom
| | - M Edward Medof
- Institute of Pathology, Case Western Reserve University, Cleveland, Ohio 44106.
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25
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Rich RL, Myszka DG. Survey of the year 2006 commercial optical biosensor literature. J Mol Recognit 2007; 20:300-66. [DOI: 10.1002/jmr.862] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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