1
|
Voisin TB, Couves EC, Tate EW, Bubeck D. Dynamics and Molecular Interactions of GPI-Anchored CD59. Toxins (Basel) 2023; 15:430. [PMID: 37505699 PMCID: PMC10467114 DOI: 10.3390/toxins15070430] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 06/13/2023] [Accepted: 06/26/2023] [Indexed: 07/29/2023] Open
Abstract
CD59 is a GPI-anchored cell surface receptor that serves as a gatekeeper to controlling pore formation. It is the only membrane-bound inhibitor of the complement membrane attack complex (MAC), an immune pore that can damage human cells. While CD59 blocks MAC pores, the receptor is co-opted by bacterial pore-forming proteins to target human cells. Recent structures of CD59 in complexes with binding partners showed dramatic differences in the orientation of its ectodomain relative to the membrane. Here, we show how GPI-anchored CD59 can satisfy this diversity in binding modes. We present a PyLipID analysis of coarse-grain molecular dynamics simulations of a CD59-inhibited MAC to reveal residues of complement proteins (C6:Y285, C6:R407 C6:K412, C7:F224, C8β:F202, C8β:K326) that likely interact with lipids. Using modules of the MDAnalysis package to investigate atomistic simulations of GPI-anchored CD59, we discover properties of CD59 that encode the flexibility necessary to bind both complement proteins and bacterial virulence factors.
Collapse
Affiliation(s)
- Tomas B. Voisin
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London SW7 2AZ, UK
| | - Emma C. Couves
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London SW7 2AZ, UK
| | - Edward W. Tate
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, London W12 0BZ, UK
| | - Doryen Bubeck
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London SW7 2AZ, UK
| |
Collapse
|
2
|
Couves EC, Gardner S, Voisin TB, Bickel JK, Stansfeld PJ, Tate EW, Bubeck D. Structural basis for membrane attack complex inhibition by CD59. Nat Commun 2023; 14:890. [PMID: 36797260 PMCID: PMC9935631 DOI: 10.1038/s41467-023-36441-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 02/01/2023] [Indexed: 02/18/2023] Open
Abstract
CD59 is an abundant immuno-regulatory receptor that protects human cells from damage during complement activation. Here we show how the receptor binds complement proteins C8 and C9 at the membrane to prevent insertion and polymerization of membrane attack complex (MAC) pores. We present cryo-electron microscopy structures of two inhibited MAC precursors known as C5b8 and C5b9. We discover that in both complexes, CD59 binds the pore-forming β-hairpins of C8 to form an intermolecular β-sheet that prevents membrane perforation. While bound to C8, CD59 deflects the cascading C9 β-hairpins, rerouting their trajectory into the membrane. Preventing insertion of C9 restricts structural transitions of subsequent monomers and indirectly halts MAC polymerization. We combine our structural data with cellular assays and molecular dynamics simulations to explain how the membrane environment impacts the dual roles of CD59 in controlling pore formation of MAC, and as a target of bacterial virulence factors which hijack CD59 to lyse human cells.
Collapse
Affiliation(s)
- Emma C Couves
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London, SW7 2AZ, United Kingdom
| | - Scott Gardner
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London, SW7 2AZ, United Kingdom
| | - Tomas B Voisin
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London, SW7 2AZ, United Kingdom
| | - Jasmine K Bickel
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London, SW7 2AZ, United Kingdom
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, London, W12 0BZ, United Kingdom
| | - Phillip J Stansfeld
- School of Life Sciences and Department of Chemistry, Gibbet Hill Campus, The University of Warwick, Coventry, CV4 7AL, United Kingdom
| | - Edward W Tate
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, London, W12 0BZ, United Kingdom
| | - Doryen Bubeck
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London, SW7 2AZ, United Kingdom.
| |
Collapse
|
3
|
Bispecific mAb2 Antibodies Targeting CD59 Enhance the Complement-Dependent Cytotoxicity Mediated by Rituximab. Int J Mol Sci 2022; 23:ijms23095208. [PMID: 35563599 PMCID: PMC9103234 DOI: 10.3390/ijms23095208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Revised: 04/29/2022] [Accepted: 05/03/2022] [Indexed: 12/04/2022] Open
Abstract
Inhibition of complement activation via the overexpression of complement-regulatory proteins (CRPs), most notably CD46, CD55 and CD59, is an efficient mechanism of disguise of cancer cells from a host immune system. This phenomenon extends to counteract the potency of therapeutic antibodies that could lyse target cells by eliciting complement cascade. The manifold functions and ubiquitous expression of CRPs preclude their systemic specific inhibition. We selected CD59-specific Fc fragments with a novel antigen binding site (Fcabs) from yeast display libraries using recombinant antigens expressed in bacterial or mammalian cells. To produce a bispecific antibody, we endowed rituximab, a clinically applied anti-CD20 antibody, used for therapy of various lymphoid malignancies, with an anti-CD59 Fcab. This bispecific antibody was able to induce more potent complement-dependent cytotoxicity for CD20 and CD59 expressing Raji cell line measured with lactate dehydrogenase-release assay, but had no effect on the cells with lower levels of the primary CD20 antigen or CD20-negative cells. Such molecules are promising candidates for future therapeutic development as they elicit a higher specific cytotoxicity at a lower concentration and hence cause a lower exhaustion of complement components.
Collapse
|
4
|
Li L, Yang W, Shen Y, Xu X, Li J. Fish complement C8 evolution, functional network analyses, and the theoretical interaction between C8 alpha chain and CD59. Mol Immunol 2020; 128:235-248. [PMID: 33160183 DOI: 10.1016/j.molimm.2020.10.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 10/16/2020] [Accepted: 10/18/2020] [Indexed: 12/19/2022]
Abstract
Complement C8, as a main component of the membrane attack complex, has only been identified in vertebrates. C8 comprises three subunits encoded by individual genes: C8a (alpha chain), C8b (beta chain), and C8g (gamma chain). However, in fish, there have been limited studies on the evolutionary history and systematic function of C8. In the present study, phylogenetic analysis indicated the complete divergence of C8 genes in different fish species. Codon usage bias analysis revealed the evolutionary complexity of C8 genes. Selective pressure analysis found that C8 genes have been affected by negative selection during evolution. Sequence alignment identified the sites that are under selective pressure. The systematic functions of C8 were revealed by gene co-expression and protein-protein interaction (PPI) network analyses. Notably, gene ontology enrichment analysis suggested that C8 proteins in zebrafish function mainly in the neuroendocrine system. Protein structural comparisons showed that putative functional residues and domains were conserved between the C8 subunits of human and grass carp. A preliminary study on the theoretical interaction between C8a and CD59 was performed according to the simulated protein stereo structure. The first functionally-related site was absent in the simulated conformation of the grass carp (Ctenopharyngodon idella) C8a-CD59 protein complex. We speculated that Tyr63 is involved in the functional loss of CD59 binding. The docking of CD59 to four potential sites (Met390, Ser391, Leu392, and Val405) in grass carp C8a was analyzed. The results of the present study provide a deeper understanding of the evolution and function of fish complement C8.
Collapse
Affiliation(s)
- Lisen Li
- Key Laboratory of Freshwater Aquatic Genetic Resources, Ministry of Agriculture and Rural Affairs, Shanghai Ocean University, Shanghai 201306, China
| | - Weining Yang
- Key Laboratory of Freshwater Aquatic Genetic Resources, Ministry of Agriculture and Rural Affairs, Shanghai Ocean University, Shanghai 201306, China
| | - Yubang Shen
- Key Laboratory of Freshwater Aquatic Genetic Resources, Ministry of Agriculture and Rural Affairs, Shanghai Ocean University, Shanghai 201306, China.
| | - Xiaoyan Xu
- Key Laboratory of Freshwater Aquatic Genetic Resources, Ministry of Agriculture and Rural Affairs, Shanghai Ocean University, Shanghai 201306, China
| | - Jiale Li
- Key Laboratory of Freshwater Aquatic Genetic Resources, Ministry of Agriculture and Rural Affairs, Shanghai Ocean University, Shanghai 201306, China; Shanghai Engineering Research Center of Aquaculture, Shanghai Ocean University, Shanghai 201306, China.
| |
Collapse
|
5
|
Parsons ES, Stanley GJ, Pyne ALB, Hodel AW, Nievergelt AP, Menny A, Yon AR, Rowley A, Richter RP, Fantner GE, Bubeck D, Hoogenboom BW. Single-molecule kinetics of pore assembly by the membrane attack complex. Nat Commun 2019; 10:2066. [PMID: 31061395 PMCID: PMC6502846 DOI: 10.1038/s41467-019-10058-7] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 04/12/2019] [Indexed: 12/24/2022] Open
Abstract
The membrane attack complex (MAC) is a hetero-oligomeric protein assembly that kills pathogens by perforating their cell envelopes. The MAC is formed by sequential assembly of soluble complement proteins C5b, C6, C7, C8 and C9, but little is known about the rate-limiting steps in this process. Here, we use rapid atomic force microscopy (AFM) imaging to show that MAC proteins oligomerize within the membrane, unlike structurally homologous bacterial pore-forming toxins. C5b-7 interacts with the lipid bilayer prior to recruiting C8. We discover that incorporation of the first C9 is the kinetic bottleneck of MAC formation, after which rapid C9 oligomerization completes the pore. This defines the kinetic basis for MAC assembly and provides insight into how human cells are protected from bystander damage by the cell surface receptor CD59, which is offered a maximum temporal window to halt the assembly at the point of C9 insertion.
Collapse
Affiliation(s)
- Edward S Parsons
- London Centre for Nanotechnology, University College London, London, WC1H 0AH, UK.
| | - George J Stanley
- London Centre for Nanotechnology, University College London, London, WC1H 0AH, UK
| | - Alice L B Pyne
- London Centre for Nanotechnology, University College London, London, WC1H 0AH, UK
| | - Adrian W Hodel
- London Centre for Nanotechnology, University College London, London, WC1H 0AH, UK
- Institute of Structural and Molecular Biology, University College London, London, WC1E 6BT, UK
| | - Adrian P Nievergelt
- Laboratory for Bio- and Nano-Instrumentation, Swiss Federal Institute of Technology Lausanne (EPFL), 1015, Lausanne, Switzerland
| | - Anaïs Menny
- Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
| | - Alexander R Yon
- London Centre for Nanotechnology, University College London, London, WC1H 0AH, UK
- Institute of Structural and Molecular Biology, University College London, London, WC1E 6BT, UK
| | - Ashlea Rowley
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Ralf P Richter
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
- School of Physics and Astronomy, Faculty of Mathematics and Physical Sciences, University of Leeds, Leeds, LS2 9JT, UK
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Georg E Fantner
- Laboratory for Bio- and Nano-Instrumentation, Swiss Federal Institute of Technology Lausanne (EPFL), 1015, Lausanne, Switzerland
| | - Doryen Bubeck
- Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
| | - Bart W Hoogenboom
- London Centre for Nanotechnology, University College London, London, WC1H 0AH, UK.
- Institute of Structural and Molecular Biology, University College London, London, WC1E 6BT, UK.
- Department of Physics and Astronomy, University College London, London, WC1E 6BT, UK.
| |
Collapse
|
6
|
Menny A, Serna M, Boyd CM, Gardner S, Joseph AP, Morgan BP, Topf M, Brooks NJ, Bubeck D. CryoEM reveals how the complement membrane attack complex ruptures lipid bilayers. Nat Commun 2018; 9:5316. [PMID: 30552328 PMCID: PMC6294249 DOI: 10.1038/s41467-018-07653-5] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 11/12/2018] [Indexed: 01/08/2023] Open
Abstract
The membrane attack complex (MAC) is one of the immune system's first responders. Complement proteins assemble on target membranes to form pores that lyse pathogens and impact tissue homeostasis of self-cells. How MAC disrupts the membrane barrier remains unclear. Here we use electron cryo-microscopy and flicker spectroscopy to show that MAC interacts with lipid bilayers in two distinct ways. Whereas C6 and C7 associate with the outer leaflet and reduce the energy for membrane bending, C8 and C9 traverse the bilayer increasing membrane rigidity. CryoEM reconstructions reveal plasticity of the MAC pore and demonstrate how C5b6 acts as a platform, directing assembly of a giant β-barrel whose structure is supported by a glycan scaffold. Our work provides a structural basis for understanding how β-pore forming proteins breach the membrane and reveals a mechanism for how MAC kills pathogens and regulates cell functions.
Collapse
Affiliation(s)
- Anaïs Menny
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London, SW7 2AZ, UK
| | - Marina Serna
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London, SW7 2AZ, UK
- Spanish National Cancer Research Centre, CNIO, Melchor Fernández Almagro, 3.28029, Madrid, Spain
| | - Courtney M Boyd
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London, SW7 2AZ, UK
| | - Scott Gardner
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London, SW7 2AZ, UK
| | - Agnel Praveen Joseph
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, Malet Street, London, WC1E 7HX, UK
- Scientific Computing Department, Science and Technology Facilities Council, Research Complex at Harwell, Didcot, OX11 0FA, UK
| | - B Paul Morgan
- Division of Infection and Immunity, School of Medicine, Cardiff University, Heath Park, Cardiff, CF14 4XN, UK
| | - Maya Topf
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, Malet Street, London, WC1E 7HX, UK
| | - Nicholas J Brooks
- Department of Chemistry, Imperial College London, London, SW7 2AZ, UK
| | - Doryen Bubeck
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London, SW7 2AZ, UK.
| |
Collapse
|
7
|
Maugeri A, Barchitta M, Mazzone MG, Giuliano F, Agodi A. Complement System and Age-Related Macular Degeneration: Implications of Gene-Environment Interaction for Preventive and Personalized Medicine. BIOMED RESEARCH INTERNATIONAL 2018; 2018:7532507. [PMID: 30225264 PMCID: PMC6129329 DOI: 10.1155/2018/7532507] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Accepted: 07/18/2018] [Indexed: 12/14/2022]
Abstract
Age-related macular degeneration (AMD) is the most common cause of visual loss in developed countries, with a significant economic and social burden on public health. Although genome-wide and gene-candidate studies have been enabled to identify genetic variants in the complement system associated with AMD pathogenesis, the effect of gene-environment interaction is still under debate. In this review we provide an overview of the role of complement system and its genetic variants in AMD, summarizing the consequences of the interaction between genetic and environmental risk factors on AMD onset, progression, and therapeutic response. Finally, we discuss the perspectives of current evidence in the field of genomics driven personalized medicine and public health.
Collapse
Affiliation(s)
- Andrea Maugeri
- Department of Medical and Surgical Sciences and Advanced Technologies “GF Ingrassia”, University of Catania, Via S. Sofia 87, 95123 Catania, Italy
| | - Martina Barchitta
- Department of Medical and Surgical Sciences and Advanced Technologies “GF Ingrassia”, University of Catania, Via S. Sofia 87, 95123 Catania, Italy
| | - Maria Grazia Mazzone
- SIFI SpA, Research and Development Department, Via Ercole Patti 36, 95025 Catania, Italy
| | - Francesco Giuliano
- SIFI SpA, Research and Development Department, Via Ercole Patti 36, 95025 Catania, Italy
| | - Antonella Agodi
- Department of Medical and Surgical Sciences and Advanced Technologies “GF Ingrassia”, University of Catania, Via S. Sofia 87, 95123 Catania, Italy
| |
Collapse
|
8
|
Siqueira GH, de Souza GO, Heinemann MB, Vasconcellos SA, Nascimento ALTO. The role of Lsa23 to mediate the interaction of Leptospira interrogans with the terminal complement components pathway. Microb Pathog 2017; 112:182-189. [PMID: 28963011 DOI: 10.1016/j.micpath.2017.09.058] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Revised: 09/19/2017] [Accepted: 09/26/2017] [Indexed: 11/18/2022]
Abstract
Leptospirosis is a severe worldwide zoonotic disease caused by pathogenic Leptospira spp. It has been demonstrated that pathogenic leptospires are resistant to the bactericidal activity of normal human serum while saprophytic strains are susceptible. Pathogenic strains have the ability to bind soluble complement regulators and these activities are thought to contribute to bacterial immune evasion. One strategy used by some pathogens to evade the complement cascade, which is not well explored, is to block the terminal pathway. We have, thus, examined whether leptospires are able to interact with components of the terminal complement pathway. ELISA screening using anti-leptospires serum has shown that the pathogenic, virulent strain L. interrogans L1-130 can bind to immobilized human C8 (1 μg). However, virulent and saprophyte L. biflexa strains showed the ability to interact with C8 and C9, when these components were employed at physiological concentration (50 μg/mL), but the virulent strain seemed more competent. Lsa23, a putative leptospiral adhesin only present in pathogenic strains, interacts with C8 and C9 in a dose-dependent mode, suggesting that this protein could mediate the binding of virulent Leptospira with these components. To our knowledge, this is the first work reporting the binding of Leptospira to C8 and C9 terminal complement components, suggesting that the inhibition of this pathway is part of the strategy used by leptospires to evade the innate immunity.
Collapse
Affiliation(s)
- Gabriela H Siqueira
- Centro de Biotecnologia, Instituto Butantan, Avenida Vital Brazil, 1500, 05503-900 São Paulo, SP, Brazil
| | - Gisele O de Souza
- Laboratório de Zoonoses Bacterianas do VPS, Faculdade de Medicina Veterinária e Zootecnia, USP, Avenida Prof. Dr. Orlando Marques de Paiva, 87, 05508-270, São Paulo, SP, Brazil
| | - Marcos B Heinemann
- Laboratório de Zoonoses Bacterianas do VPS, Faculdade de Medicina Veterinária e Zootecnia, USP, Avenida Prof. Dr. Orlando Marques de Paiva, 87, 05508-270, São Paulo, SP, Brazil
| | - Silvio A Vasconcellos
- Laboratório de Zoonoses Bacterianas do VPS, Faculdade de Medicina Veterinária e Zootecnia, USP, Avenida Prof. Dr. Orlando Marques de Paiva, 87, 05508-270, São Paulo, SP, Brazil
| | - Ana L T O Nascimento
- Centro de Biotecnologia, Instituto Butantan, Avenida Vital Brazil, 1500, 05503-900 São Paulo, SP, Brazil.
| |
Collapse
|
9
|
Bayly-Jones C, Bubeck D, Dunstone MA. The mystery behind membrane insertion: a review of the complement membrane attack complex. Philos Trans R Soc Lond B Biol Sci 2017; 372:20160221. [PMID: 28630159 PMCID: PMC5483522 DOI: 10.1098/rstb.2016.0221] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/08/2016] [Indexed: 12/14/2022] Open
Abstract
The membrane attack complex (MAC) is an important innate immune effector of the complement terminal pathway that forms cytotoxic pores on the surface of microbes. Despite many years of research, MAC structure and mechanism of action have remained elusive, relying heavily on modelling and inference from biochemical experiments. Recent advances in structural biology, specifically cryo-electron microscopy, have provided new insights into the molecular mechanism of MAC assembly. Its unique 'split-washer' shape, coupled with an irregular giant β-barrel architecture, enable an atypical mechanism of hole punching and represent a novel system for which to study pore formation. This review will introduce the complement terminal pathway that leads to formation of the MAC. Moreover, it will discuss how structures of the pore and component proteins underpin a mechanism for MAC function, modulation and inhibition.This article is part of the themed issue 'Membrane pores: from structure and assembly, to medicine and technology'.
Collapse
Affiliation(s)
- Charles Bayly-Jones
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton Campus, Melbourne, Victoria 3800, Australia
- ARC Centre of Excellence in Advanced Molecular Imaging, Biomedicine Discovery Institute, Monash University, Clayton Campus, Melbourne, Victoria 3800, Australia
| | - Doryen Bubeck
- Department of Life Sciences, Imperial College London, South Kensington Campus, London SW2 7AZ, UK
| | - Michelle A Dunstone
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton Campus, Melbourne, Victoria 3800, Australia
- ARC Centre of Excellence in Advanced Molecular Imaging, Biomedicine Discovery Institute, Monash University, Clayton Campus, Melbourne, Victoria 3800, Australia
| |
Collapse
|
10
|
Neely AE, Mandigo KA, Robinson RL, Ness TL, Weiland MH. Chimeric approach for narrowing a membrane-inserting region within human perforin. Protein Eng Des Sel 2016; 30:105-111. [PMID: 27980121 DOI: 10.1093/protein/gzw069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 11/14/2016] [Accepted: 11/21/2016] [Indexed: 11/13/2022] Open
Abstract
Perforin is a pore-forming, immune protein that functions to deliver an apoptotic cocktail of proteins into a target pathogen. Recent studies of the bacterial cholesterol-dependent cytolysins (CDCs) have provided a model for perforin's pore-forming mechanism. Both perforin and CDC family members share a conserved β-sheet flanked by two clusters of α-helices. Within the CDCs, these helices refold into two transmembrane β-hairpins, TMH1 and TMH2. Based upon structural conservation and electron microscopy imaging, the analogous helices within perforin are predicted to also be membrane inserting; however, these regions are approximately twice the length of the CDC TMHs. To test the membrane-insertion potential of one of these regions, chimeras were created using a well-characterized CDC, perfringolysin-O (PFO), as the backbone of these constructs. PFO's TMH2 region was replaced with perforin's corresponding helical region. Although hemolytic activity was observed, the chimera was poorly soluble. A second chimera contained the same region truncated to match the length of the PFO TMH2 region. The truncated chimera demonstrated improved solubility, significant hemolytic activity and the ability to form pores characteristic of those created by PFO. These results provide the first evidence that perforin's helices function as TMHs and more importantly narrows the residues responsible for membrane insertion.
Collapse
Affiliation(s)
- Amy E Neely
- Department of Chemistry and Physics, Armstrong State University, Savannah, GA 31419, USA
| | - Kimberly A Mandigo
- Department of Chemistry and Physics, Armstrong State University, Savannah, GA 31419, USA
| | - Rebekah L Robinson
- Department of Chemistry and Physics, Armstrong State University, Savannah, GA 31419, USA.,Department of Biology, Armstrong State University, Savannah, GA 31419, USA
| | - Traci L Ness
- Department of Biology, Armstrong State University, Savannah, GA 31419, USA
| | - Mitch H Weiland
- Department of Chemistry and Physics, Armstrong State University, Savannah, GA 31419, USA
| |
Collapse
|
11
|
Morgan BP, Walters D, Serna M, Bubeck D. Terminal complexes of the complement system: new structural insights and their relevance to function. Immunol Rev 2016; 274:141-151. [PMID: 27782334 DOI: 10.1111/imr.12461] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Complement is a key component of innate immunity in health and a powerful driver of inflammation and tissue injury in disease. The biological and pathological effects of complement activation are mediated by activation products. These come in two flavors: (i) proteolytic fragments of complement proteins (C3, C4, C5) generated during activation that bind specific receptors on target cells to mediate effects; (ii) the multimolecular membrane attack complex generated from the five terminal complement proteins that directly binds to and penetrates target cell membranes. Several recent publications have described structural insights that have changed perceptions of the nature of this membrane attack complex. This review will describe these recent advances in understanding of the structure of the membrane attack complex and its by-product the fluid-phase terminal complement complex and relate these new structural insights to functional consequences and cell responses to complement membrane attack.
Collapse
Affiliation(s)
- Bryan Paul Morgan
- Systems Immunity Research Institute, Division of Infection and Immunity, School of Medicine, Cardiff University, Cardiff, UK.
| | - David Walters
- Systems Immunity Research Institute, Division of Infection and Immunity, School of Medicine, Cardiff University, Cardiff, UK
| | - Marina Serna
- Faculty of Natural Sciences, Department of Life Sciences, Imperial College, London, UK
| | - Doryen Bubeck
- Faculty of Natural Sciences, Department of Life Sciences, Imperial College, London, UK
| |
Collapse
|
12
|
Conformational changes during pore formation by the perforin-related protein pleurotolysin. PLoS Biol 2015; 13:e1002049. [PMID: 25654333 PMCID: PMC4318580 DOI: 10.1371/journal.pbio.1002049] [Citation(s) in RCA: 98] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Accepted: 12/10/2014] [Indexed: 12/17/2022] Open
Abstract
Membrane attack complex/perforin-like (MACPF) proteins comprise the largest superfamily of pore-forming proteins, playing crucial roles in immunity and pathogenesis. Soluble monomers assemble into large transmembrane pores via conformational transitions that remain to be structurally and mechanistically characterised. Here we present an 11 Å resolution cryo-electron microscopy (cryo-EM) structure of the two-part, fungal toxin Pleurotolysin (Ply), together with crystal structures of both components (the lipid binding PlyA protein and the pore-forming MACPF component PlyB). These data reveal a 13-fold pore 80 Å in diameter and 100 Å in height, with each subunit comprised of a PlyB molecule atop a membrane bound dimer of PlyA. The resolution of the EM map, together with biophysical and computational experiments, allowed confident assignment of subdomains in a MACPF pore assembly. The major conformational changes in PlyB are a ∼70° opening of the bent and distorted central β-sheet of the MACPF domain, accompanied by extrusion and refolding of two α-helical regions into transmembrane β-hairpins (TMH1 and TMH2). We determined the structures of three different disulphide bond-trapped prepore intermediates. Analysis of these data by molecular modelling and flexible fitting allows us to generate a potential trajectory of β-sheet unbending. The results suggest that MACPF conformational change is triggered through disruption of the interface between a conserved helix-turn-helix motif and the top of TMH2. Following their release we propose that the transmembrane regions assemble into β-hairpins via top down zippering of backbone hydrogen bonds to form the membrane-inserted β-barrel. The intermediate structures of the MACPF domain during refolding into the β-barrel pore establish a structural paradigm for the transition from soluble monomer to pore, which may be conserved across the whole superfamily. The TMH2 region is critical for the release of both TMH clusters, suggesting why this region is targeted by endogenous inhibitors of MACPF function. Animals, plants, fungi, and bacteria all use pore-forming proteins of the membrane attack complex-perforin (MACPF) family as lethal, cell-killing weapons. These proteins are able to insert into the plasma membranes of target cells, creating large pores that short circuit the natural separation between the intracellular and extracellular milieu, with catastrophic results. However, the pore-forming proteins must undergo a substantial transformation from soluble precursors to a large barrel-shaped transmembrane complex as they punch their way into cells. Using a combination of X-ray crystallography and cryo electron microscopy, we have visualized, for the first time, the mechanism of action of one of these pore-forming proteins—pleurotolysin, a MACPF protein from the edible oyster mushroom. This enabled us to propose a model of the pleurotolysin pore by fitting the crystallographic structures of the pore proteins into a three-dimensional map of the pore obtained by cryo electron microscopy. We then designed a set of double mutants that allowed us to chemically trap intermediate states along the trajectory of the pore formation process, and to determine their structures too. By combining these data we proposed a detailed molecular mechanism for pore formation. The pleurotolysin first assembles into rings of 13 subunits, each of which then opens up by about 70° during pore formation. This process is accompanied by refolding and extrusion of two compact regions from each subunit into long hairpins that then zipper together to form an 80-Å wide barrel-shaped channel through the membrane. A combination of structural methods reveals the complex process by which the perforin-like fungal toxin Pleurotolysin rearranges its structure to form a pore that punches a hole in target cell membranes.
Collapse
|
13
|
Abstract
The complement system is an intricate network of serum proteins that mediates humoral innate immunity through an amplification cascade that ultimately leads to recruitment of inflammatory cells or opsonisation or killing of pathogens. One effector arm of this network is the terminal pathway of complement, which leads to the formation of the membrane attack complex (MAC) composed of complement components C5b, C6, C7, C8 and C9. Upon formation of C5 convertases via the classical or alternative pathways of complement activation, C5b is generated from C5 by proteolytic cleavage, nucleating a series of association and polymerisation reactions of the MAC-constituting complement components that culminate in pore formation of pathogenic membranes. Recent structures of MAC components and homologous proteins significantly increased our understanding of oligomerisation, membrane association and integration, shedding light onto the molecular mechanism of this important branch of the innate immune system.
Collapse
|
14
|
Hotze EM, Tweten RK. Membrane assembly of the cholesterol-dependent cytolysin pore complex. BIOCHIMICA ET BIOPHYSICA ACTA 2012; 1818:1028-38. [PMID: 21835159 PMCID: PMC3243806 DOI: 10.1016/j.bbamem.2011.07.036] [Citation(s) in RCA: 143] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Accepted: 07/24/2011] [Indexed: 12/16/2022]
Abstract
The cholesterol-dependent cytolysins (CDCs) are a large family of pore-forming toxins that are produced, secreted and contribute to the pathogenesis of many species of Gram-positive bacteria. The assembly of the CDC pore-forming complex has been under intense study for the past 20 years. These studies have revealed a molecular mechanism of pore formation that exhibits many novel features. The CDCs form large β-barrel pore complexes that are assembled from 35 to 40 soluble CDC monomers. Pore formation is dependent on the presence of membrane cholesterol, which functions as the receptor for most CDCs. Cholesterol binding initiates significant secondary and tertiary structural changes in the monomers, which lead to the assembly of a large membrane embedded β-barrel pore complex. This review will focus on the molecular mechanism of assembly of the CDC membrane pore complex and how these studies have led to insights into the mechanism of pore formation for other pore-forming proteins. This article is part of a Special Issue entitled: Protein Folding in Membranes.
Collapse
Affiliation(s)
- Eileen M. Hotze
- Department of Microbiology and Immunology, The University of Oklahoma Sciences Center, Oklahoma City, Oklahoma 73104, USA
| | - Rodney K. Tweten
- Department of Microbiology and Immunology, The University of Oklahoma Sciences Center, Oklahoma City, Oklahoma 73104, USA
| |
Collapse
|
15
|
Carter AM. Complement activation: an emerging player in the pathogenesis of cardiovascular disease. SCIENTIFICA 2012; 2012:402783. [PMID: 24278688 PMCID: PMC3820556 DOI: 10.6064/2012/402783] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Accepted: 11/06/2012] [Indexed: 05/08/2023]
Abstract
A wealth of evidence indicates a fundamental role for inflammation in the pathogenesis of cardiovascular disease (CVD), contributing to the development and progression of atherosclerotic lesion formation, plaque rupture, and thrombosis. An increasing body of evidence supports a functional role for complement activation in the pathogenesis of CVD through pleiotropic effects on endothelial and haematopoietic cell function and haemostasis. Prospective and case control studies have reported strong relationships between several complement components and cardiovascular outcomes, and in vitro studies and animal models support a functional effect. Complement activation, in particular, generation of C5a and C5b-9, influences many processes involved in the development and progression of atherosclerosis, including promotion of endothelial cell activation, leukocyte infiltration into the extracellular matrix, stimulation of cytokine release from vascular smooth muscle cells, and promotion of plaque rupture. Complement activation also influences thrombosis, involving components of the mannose-binding lectin pathway, and C5b-9 in particular, through activation of platelets, promotion of fibrin formation, and impairment of fibrinolysis. The participation of the complement system in inflammation and thrombosis is consistent with the physiological role of the complement system as a rapid effector system conferring protection following vessel injury. However, in the context of CVD, these same processes contribute to development of atherosclerosis, plaque rupture, and thrombosis.
Collapse
Affiliation(s)
- Angela M. Carter
- Division of Epidemiology, Leeds Institute of Genetics, Health and Therapeutics, Faculty of Medicine and Health and the Multidisciplinary Cardiovascular Research Centre, University of Leeds, Clarendon Way, Leeds LS2 9JT, UK
- *Angela M. Carter:
| |
Collapse
|
16
|
Lovelace LL, Cooper CL, Sodetz JM, Lebioda L. Structure of human C8 protein provides mechanistic insight into membrane pore formation by complement. J Biol Chem 2011; 286:17585-92. [PMID: 21454577 PMCID: PMC3093833 DOI: 10.1074/jbc.m111.219766] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Revised: 03/23/2011] [Indexed: 11/06/2022] Open
Abstract
C8 is one of five complement proteins that assemble on bacterial membranes to form the lethal pore-like "membrane attack complex" (MAC) of complement. The MAC consists of one C5b, C6, C7, and C8 and 12-18 molecules of C9. C8 is composed of three genetically distinct subunits, C8α, C8β, and C8γ. The C6, C7, C8α, C8β, and C9 proteins are homologous and together comprise the MAC family of proteins. All contain N- and C-terminal modules and a central 40-kDa membrane attack complex perforin (MACPF) domain that has a key role in forming the MAC pore. Here, we report the 2.5 Å resolution crystal structure of human C8 purified from blood. This is the first structure of a MAC family member and of a human MACPF-containing protein. The structure shows the modules in C8α and C8β are located on the periphery of C8 and not likely to interact with the target membrane. The C8γ subunit, a member of the lipocalin family of proteins that bind and transport small lipophilic molecules, shows no occupancy of its putative ligand-binding site. C8α and C8β are related by a rotation of ∼22° with only a small translational component along the rotation axis. Evolutionary arguments suggest the geometry of binding between these two subunits is similar to the arrangement of C9 molecules within the MAC pore. This leads to a model of the MAC that explains how C8-C9 and C9-C9 interactions could facilitate refolding and insertion of putative MACPF transmembrane β-hairpins to form a circular pore.
Collapse
Affiliation(s)
- Leslie L. Lovelace
- From the Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208
| | - Christopher L. Cooper
- From the Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208
| | - James M. Sodetz
- From the Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208
| | - Lukasz Lebioda
- From the Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208
| |
Collapse
|
17
|
Wei LN, Loh HH. Transcriptional and epigenetic regulation of opioid receptor genes: present and future. Annu Rev Pharmacol Toxicol 2011; 51:75-97. [PMID: 20868272 DOI: 10.1146/annurev-pharmtox-010510-100605] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Three opioid receptors (ORs) are known: μ opioid receptors (MORs), δ opioid receptors (DORs), and κ opioid receptors (KORs). Each is encoded by a distinct gene, and the three OR genes share a highly conserved genomic structure and promoter features, including an absence of TATA boxes and sensitivity to extracellular stimuli and epigenetic regulation. However, each of the genes is differentially expressed. Transcriptional regulation engages both basal and regulated transcriptional machineries and employs activating and silencing mechanisms. In retinoic acid-induced neuronal differentiation, the opioid receptor genes undergo drastically different chromatin remodeling processes and display varied patterns of epigenetic marks. Regulation of KOR expression is distinctly complex, and KOR exerts a unique function in neurite extension, indicating that KOR is not simply a pharmacological cousin of MOR and DOR. As the expression of OR proteins is ultimately controlled by extensive posttranscriptional processing, the pharmacological implication of OR gene regulation at the transcriptional level remains to be determined.
Collapse
Affiliation(s)
- Li-Na Wei
- Department of Pharmacology, University of Minnesota Medical School, Minneapolis, 55455, USA.
| | | |
Collapse
|
18
|
Bubeck D, Roversi P, Donev R, Morgan BP, Llorca O, Lea SM. Structure of human complement C8, a precursor to membrane attack. J Mol Biol 2010; 405:325-30. [PMID: 21073882 PMCID: PMC3021121 DOI: 10.1016/j.jmb.2010.10.031] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2010] [Revised: 10/13/2010] [Accepted: 10/19/2010] [Indexed: 11/25/2022]
Abstract
Complement component C8 plays a pivotal role in the formation of the membrane attack complex (MAC), an important antibacterial immune effector. C8 initiates membrane penetration and coordinates MAC pore formation. High-resolution structures of C8 subunits have provided some insight into the function of the C8 heterotrimer; however, there is no structural information describing how the intersubunit organization facilitates MAC assembly. We have determined the structure of C8 by electron microscopy and fitted the C8α-MACPF (membrane attack complex/perforin)-C8γ co-crystal structure and a homology model for C8β-MACPF into the density. Here, we demonstrate that both the C8γ protrusion and the C8α-MACPF region that inserts into the membrane upon activation are accessible.
Collapse
Affiliation(s)
- Doryen Bubeck
- University of Oxford, Wellcome Trust Centre for Human Genetics, Oxford OX3 7BN, UK
| | | | | | | | | | | |
Collapse
|
19
|
Marron Fdez de Velasco E, Law PY, Rodríguez RE. Mu opioid receptor from the zebrafish exhibits functional characteristics as those of mammalian mu opioid receptor. Zebrafish 2009; 6:259-68. [PMID: 19761379 DOI: 10.1089/zeb.2009.0594] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The functional characterization of the mu opioid receptor from the zebrafish (zfMOR) is reported here. After transfection in HEK-293 cell line, using both peptidergic and nonpeptidergic opioid ligands in the competition and saturation-binding experiments, in addition to the functional assays of (35)S-GTPgammaS-binding assays and intracellular 3'-5'-cyclic adenosine monophosphate (cAMP) level determinations, we demonstrate that zfMOR exhibits a pharmacological profile similar to that of the mammalian MOR. Besides, the internalization process of zfMOR after opiate agonist treatment (morphine, DAMGO, etorphine) resembles the pattern observed for its mammalian counterpart. These similarities suggest that the zebrafish is a good model for the study of the opioid effects in development.
Collapse
Affiliation(s)
- Ezequiel Marron Fdez de Velasco
- Department of Biochemistry and Molecular Biology, Institute of Neurosciences of Castilla y León, University of Salamanca, Salamanca, Spain
| | | | | |
Collapse
|
20
|
Slade DJ, Lovelace LL, Chruszcz M, Minor W, Lebioda L, Sodetz JM. Crystal structure of the MACPF domain of human complement protein C8 alpha in complex with the C8 gamma subunit. J Mol Biol 2008; 379:331-42. [PMID: 18440555 DOI: 10.1016/j.jmb.2008.03.061] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2008] [Revised: 03/21/2008] [Accepted: 03/21/2008] [Indexed: 11/27/2022]
Abstract
Human C8 is one of five complement components (C5b, C6, C7, C8, and C9) that assemble on bacterial membranes to form a porelike structure referred to as the "membrane attack complex" (MAC). C8 contains three genetically distinct subunits (C8 alpha, C8 beta, C8 gamma) arranged as a disulfide-linked C8 alpha-gamma dimer that is noncovalently associated with C8 beta. C6, C7 C8 alpha, C8 beta, and C9 are homologous. All contain N- and C-terminal modules and an intervening 40-kDa segment referred to as the membrane attack complex/perforin (MACPF) domain. The C8 gamma subunit is unrelated and belongs to the lipocalin family of proteins that display a beta-barrel fold and generally bind small, hydrophobic ligands. Several hundred proteins with MACPF domains have been identified based on sequence similarity; however, the structure and function of most are unknown. Crystal structures of the secreted bacterial protein Plu-MACPF and the human C8 alpha MACPF domain were recently reported and both display a fold similar to those of the bacterial pore-forming cholesterol-dependent cytolysins (CDCs). In the present study, we determined the crystal structure of the human C8 alpha MACPF domain disulfide-linked to C8 gamma (alphaMACPF-gamma) at 2.15 A resolution. The alphaMACPF portion has the predicted CDC-like fold and shows two regions of interaction with C8 gamma. One is in a previously characterized 19-residue insertion (indel) in C8 alpha and fills the entrance to the putative C8 gamma ligand-binding site. The second is a hydrophobic pocket that makes contact with residues on the side of the C8 gamma beta-barrel. The latter interaction induces conformational changes in alphaMACPF that are likely important for C8 function. Also observed is structural conservation of the MACPF signature motif Y/W-G-T/S-H-F/Y-X(6)-G-G in alphaMACPF and Plu-MACPF, and conservation of several key glycine residues known to be important for refolding and pore formation by CDCs.
Collapse
Affiliation(s)
- Daniel J Slade
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208, USA
| | | | | | | | | | | |
Collapse
|
21
|
Afarinesh MR, Sheibani V, Arabzadeh S, Shamsizadeh A. Effect of chronic morphine exposure on response properties of rat barrel cortex neurons. Addict Biol 2008; 13:31-9. [PMID: 18201293 DOI: 10.1111/j.1369-1600.2007.00087.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Chronic exposure to morphine can impair performance in tasks which need sensory processing. Using single unit recordings we investigate the effect of chronic morphine exposure on the firing properties of neurons in layers IV and V of the whisker-related area of rat primary somatosensory cortex. In urethane-anesthetized animals, neuronal activity was recorded in response to principal and adjacent whisker deflections either stimulated independently or in a conditioning test paradigm. A condition test ratio (CTR) was calculated for assessing the inhibitory receptive field. In layer IV, chronic morphine treatment did not change the spontaneous discharge activity. On responses to principal and adjacent whisker deflections did not show any significant changes following chronic morphine exposure. The magnitude Off responses to adjacent whisker deflection decreased while its response latency increased. In addition, there was a significant increase in the latency of Off responses to principal whisker deflection. CTR did not change significantly following morphine exposure. Layer V neurons, on the other hand, did not show any significant changes in their spontaneous activity or their evoked responses following morphine exposure. Our results suggest that chronic morphine exposure has a subtle modulatory effect on response properties of neurons in barrel cortex.
Collapse
|
22
|
Lovelace LL, Chiswell B, Slade DJ, Sodetz JM, Lebioda L. Crystal structure of complement protein C8γ in complex with a peptide containing the C8γ binding site on C8α: Implications for C8γ ligand binding. Mol Immunol 2008; 45:750-6. [PMID: 17692377 DOI: 10.1016/j.molimm.2007.06.359] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2007] [Revised: 06/20/2007] [Accepted: 06/29/2007] [Indexed: 11/24/2022]
Abstract
Human C8 is one of five complement components (C5b, C6, C7, C8 and C9) that interact to form the cytolytic membrane attack complex. It contains three genetically distinct subunits; C8alpha and C8gamma form a disulfide-linked C8alpha-gamma heterodimer that is noncovalently associated with C8beta. The C8alpha subunit is homologous to C8beta, C6, C7 and C9 and together they form the MAC family of proteins. By contrast, C8gamma is the only lipocalin in the complement system. Like other lipocalins, it has a core beta-barrel structure forming a calyx with a distinct binding pocket for a small and as yet unidentified ligand. The binding site on C8alpha for C8gamma was previously localized to a 19-residue segment which contains an insertion (indel) that is unique to C8alpha. Included in the indel is C8alpha Cys 164 which links to Cys 40 in C8gamma. In the present study, C8gamma containing a C40A substitution was co-crystallized with a synthetic indel peptide containing the equivalent of a C8alpha C164A substitution. The X-ray crystal structure shows that the indel peptide completely fills the upper portion of the putative C8gamma ligand binding pocket and is in contact with all four loops at the calyx entrance. The lower part of the C8gamma cavity is either unoccupied or contains disordered solvent. The validity of the structure is supported by the spatial arrangement of C8alpha Ala 164 in the peptide and C8gamma Ala 40, which are within disulfide-bonding distance of each other. Corresponding studies in solution indicate the C8gamma ligand binding site is also occupied by the indel segment of C8alpha in whole C8. These results suggest a role for C8alpha in regulating access to the putative C8gamma ligand binding site.
Collapse
Affiliation(s)
- Leslie L Lovelace
- Department of Chemistry and Biochemistry and School of Medicine, University of South Carolina, Columbia, SC 29208, United States
| | | | | | | | | |
Collapse
|
23
|
Hadders MA, Beringer DX, Gros P. Structure of C8alpha-MACPF reveals mechanism of membrane attack in complement immune defense. Science 2007; 317:1552-4. [PMID: 17872444 DOI: 10.1126/science.1147103] [Citation(s) in RCA: 198] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Membrane attack is important for mammalian immune defense against invading microorganisms and infected host cells. Proteins of the complement membrane attack complex (MAC) and the protein perforin share a common MACPF domain that is responsible for membrane insertion and pore formation. We determined the crystal structure of the MACPF domain of complement component C8alpha at 2.5 angstrom resolution and show that it is structurally homologous to the bacterial, pore-forming, cholesterol-dependent cytolysins. The structure displays two regions that (in the bacterial cytolysins) refold into transmembrane beta hairpins, forming the lining of a barrel pore. Local hydrophobicity explains why C8alpha is the first complement protein to insert into the membrane. The size of the MACPF domain is consistent with known C9 pore sizes. These data imply that these mammalian and bacterial cytolytic proteins share a common mechanism of membrane insertion.
Collapse
Affiliation(s)
- Michael A Hadders
- Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, Netherlands
| | | | | |
Collapse
|
24
|
Rosado CJ, Buckle AM, Law RHP, Butcher RE, Kan WT, Bird CH, Ung K, Browne KA, Baran K, Bashtannyk-Puhalovich TA, Faux NG, Wong W, Porter CJ, Pike RN, Ellisdon AM, Pearce MC, Bottomley SP, Emsley J, Smith AI, Rossjohn J, Hartland EL, Voskoboinik I, Trapani JA, Bird PI, Dunstone MA, Whisstock JC. A common fold mediates vertebrate defense and bacterial attack. Science 2007; 317:1548-51. [PMID: 17717151 DOI: 10.1126/science.1144706] [Citation(s) in RCA: 237] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Proteins containing membrane attack complex/perforin (MACPF) domains play important roles in vertebrate immunity, embryonic development, and neural-cell migration. In vertebrates, the ninth component of complement and perforin form oligomeric pores that lyse bacteria and kill virus-infected cells, respectively. However, the mechanism of MACPF function is unknown. We determined the crystal structure of a bacterial MACPF protein, Plu-MACPF from Photorhabdus luminescens, to 2.0 angstrom resolution. The MACPF domain reveals structural similarity with poreforming cholesterol-dependent cytolysins (CDCs) from Gram-positive bacteria. This suggests that lytic MACPF proteins may use a CDC-like mechanism to form pores and disrupt cell membranes. Sequence similarity between bacterial and vertebrate MACPF domains suggests that the fold of the CDCs, a family of proteins important for bacterial pathogenesis, is probably used by vertebrates for defense against infection.
Collapse
Affiliation(s)
- Carlos J Rosado
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC 3800, Australia
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
25
|
Huang Y, Qiao F, Abagyan R, Hazard S, Tomlinson S. Defining the CD59-C9 binding interaction. J Biol Chem 2006; 281:27398-404. [PMID: 16844690 DOI: 10.1074/jbc.m603690200] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
CD59 is a membrane glycoprotein that regulates formation of the cytolytic membrane attack complex (MAC or C5b-9) on host cell membranes. It functions by binding to C8 (alpha chain) and C9 after their structural rearrangement during MAC assembly. Previous studies indicated that the CD59 binding site in C9 was located within a 25-residue disulfide-bonded loop, and in C8alpha was located within a 51-residue sequence that overlaps the CD59 binding region of C9. By peptide screens and the use of peptides in binding assays, functional assays, and computer modeling and docking studies, we have identified a 6-residue sequence of human C9, spanning residues 365-371, as the primary CD59 recognition domain involved in CD59-mediated regulation of MAC formation. The data also indicate that both C8alpha and C9 bind to a similar or overlapping site on CD59. Furthermore, data from CD59-peptide docking models are consistent with the C9 binding site on CD59 located at a hydrophobic pocket, putatively identified previously by CD59 mutational and modeling studies.
Collapse
Affiliation(s)
- Yuxiang Huang
- Department of Microbiology and Immunology, Medical University of South Carolina, South Carolina 29403, USA
| | | | | | | | | |
Collapse
|
26
|
Slade DJ, Chiswell B, Sodetz JM. Functional Studies of the MACPF Domain of Human Complement Protein C8α Reveal Sites for Simultaneous Binding of C8β, C8γ, and C9. Biochemistry 2006; 45:5290-6. [PMID: 16618117 DOI: 10.1021/bi0601860] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Human C8 is one of five components of the membrane attack complex of complement (MAC). It contains three subunits (C8alpha, C8beta, C8gamma) arranged as a disulfide-linked C8alpha-gamma dimer that is noncovalently associated with C8beta. C8alpha, C8beta, and complement components C6, C7, and C9 form the MAC family of proteins. All contain N- and C-terminal modules and an intervening 40-kDa segment referred to as the membrane attack complex/perforin (MACPF) domain. During MAC formation, C8alpha binds and mediates the self-polymerization of C9 to form a pore-like structure on target cells. The C9 binding site was previously shown to reside within a 52-kDa segment composed of the C8alpha N-terminal modules and MACPF domain (alphaMACPF). In the present study, we examined the role of the MACPF domain in binding C9. Recombinant alphaMACPF and a disulfide-linked alphaMACPF-gamma dimer were successfully produced in Escherichia coli and purified. alphaMACPF was shown to simultaneously bind C8beta, C8gamma, and C9 and form a noncovalent alphaMACPF.C8beta.C8gamma.C9 complex. Similar results were obtained for the recombinant alphaMACPF-gamma dimer. This dimer bound C8beta and C9 to form a hemolytically active (alphaMACPF-gamma).C8beta.C9 complex. These results indicate that the principal binding site for C9 lies within the MACPF domain of C8alpha. They also suggest this site and the binding sites for C8beta and C8gamma are distinct. alphaMACPF is the first human MACPF domain to be produced recombinantly and in a functional form. Such a result suggests that this segment of C8alpha and corresponding segments of the other MAC family members are independently folded domains.
Collapse
Affiliation(s)
- Daniel J Slade
- Department of Chemistry and Biochemistry and School of Medicine, University of South Carolina, Columbia, South Carolina 29208, USA
| | | | | |
Collapse
|
27
|
Pan YX. Diversity and Complexity of the Mu Opioid Receptor Gene: Alternative Pre-mRNA Splicing and Promoters. DNA Cell Biol 2005; 24:736-50. [PMID: 16274294 DOI: 10.1089/dna.2005.24.736] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Mu opioid receptors play an important role in mediating the actions of a class of opioids including morphine and heroin. Binding and pharmacological studies have proposed several mu opioid receptor subtypes: mu(1), mu(2), and morphine-6beta-glucuronide (M6G). The cloning of a mu opioid receptor, MOR-1, has provided an invaluable tool to explore pharmacological and physiological functions of mu opioid receptors at the molecular level. However, only one mu opioid receptor (Oprm) gene has been isolated. Alternative pre-mRNA splicing has been proposed as a molecular explanation for the existence of pharmacologically identified subtypes. In recent years, we have extensively investigated alternative splicing of the Oprm gene, particularly of the mouse Oprm gene. So far we have identified 25 splice variants from the mouse Oprm gene, which are controlled by two diverse promoters, eight splice variants from the rat Oprm gene, and 11 splice variants from the human Oprm gene. Diversity and complexity of the Oprm gene was further demonstrated by functional differences in agonist-induced G protein activation, adenylyl cyclase activity, and receptor internalization among carboxyl terminal variants. This review summarizes these recent results and provides a new perspective on understanding and exploring complex opioid actions in animals and humans.
Collapse
Affiliation(s)
- Ying-Xian Pan
- Department of Neurology, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA.
| |
Collapse
|
28
|
Huang Y, Smith CA, Song H, Morgan BP, Abagyan R, Tomlinson S. Insights into the Human CD59 Complement Binding Interface Toward Engineering New Therapeutics. J Biol Chem 2005; 280:34073-9. [PMID: 16079145 DOI: 10.1074/jbc.m504922200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
CD59 is a 77-amino acid membrane glycoprotein that plays an important role in regulating the terminal pathway of complement by inhibiting formation of the cytolytic membrane attack complex (MAC or C5b-9). The MAC is formed by the self assembly of C5b, C6, C7, C8, and multiple C9 molecules, with CD59 functioning by binding C5b-8 and C5b-9 in the assembling complex. We performed a scanning alanine mutagenesis screen of residues 16-57, a region previously identified to contain the C8/C9 binding interface. We have also created an improved NMR model from previously published data for structural understanding of CD59. Based on the scanning mutagenesis data, refined models, and additional site-specific mutations, we identified a binding interface that is much broader than previously thought. In addition to identifying substitutions that decreased CD59 activity, a surprising number of substitutions significantly enhanced CD59 activity. Because CD59 has significant therapeutic potential for the treatment of various inflammatory conditions, we investigated further the ability to enhance CD59 activity by additional mutagenesis studies. Based on the enhanced activity of membrane-bound mutant CD59 molecules, clinically relevant soluble mutant CD59-based proteins were prepared and shown to have up to a 3-fold increase in complement inhibitory activity.
Collapse
Affiliation(s)
- Yuxiang Huang
- Department of Microbiology and Immunology, Medical University of South Carolina, South Carolina 29403, USA
| | | | | | | | | | | |
Collapse
|
29
|
Giddings KS, Zhao J, Sims PJ, Tweten RK. Human CD59 is a receptor for the cholesterol-dependent cytolysin intermedilysin. Nat Struct Mol Biol 2004; 11:1173-8. [PMID: 15543155 DOI: 10.1038/nsmb862] [Citation(s) in RCA: 181] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2004] [Accepted: 09/30/2004] [Indexed: 11/08/2022]
Abstract
Cholesterol is believed to serve as the common receptor for the cholesterol-dependent cytolysins (CDCs). One member of this toxin family, Streptococcus intermedius intermedilysin (ILY), exhibits a narrow spectrum of cellular specificity that is seemingly inconsistent with this premise. We show here that ILY, via its domain 4 structure, binds to the glycosyl-phosphatidylinositol-linked membrane protein human CD59 (huCD59). CD59 is an inhibitor of the membrane attack complex of human complement. ILY specifically binds to huCD59 via residues that are the binding site for the C8alpha and C9 complement proteins. These studies provide a new model for the mechanism of cellular recognition by a CDC.
Collapse
Affiliation(s)
- Kara S Giddings
- Microbiology and Immunology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
| | | | | | | |
Collapse
|
30
|
Deng J, Gold D, LoVerde PT, Fishelson Z. Inhibition of the complement membrane attack complex by Schistosoma mansoni paramyosin. Infect Immun 2003; 71:6402-10. [PMID: 14573661 PMCID: PMC219572 DOI: 10.1128/iai.71.11.6402-6410.2003] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Larvae and adults of the parasitic blood fluke Schistosoma mansoni are resistant to killing by human complement. An earlier search by Parizade et al. for a schistosome complement inhibitor identified a 94-kDa surface protein which was named SCIP-1 (M. Parizade, R. Arnon, P. J. Lachmann, and Z. Fishelson, J. Exp. Med. 179:1625-1636, 1994). Following partial purification and analysis by mass spectrometry, we have determined SCIP-1 to be a surface-exposed form of the muscle protein paramyosin. As shown by immunofluorescence, anti-paramyosin antibodies label the surface of live schistosomula and adult worms. Like SCIP-1, purified native paramyosin reacts with a polyclonal rabbit anti-human CD59 antiserum, as shown by Western blot analysis. Also, the human complement components C8 and C9 bind to recombinant and native paramyosin. Analysis of paramyosin binding to fragments of C9 generated by thrombin or trypsin has demonstrated that paramyosin binds to C9 at a position located between Gly245 and Arg391. Paramyosin inhibited Zn(2+)-induced C9 polymerization and poly-C9 deposition onto rabbit erythrocytes (E(R)). In addition, paramyosin inhibited lysis of E(R) and of sensitized sheep erythrocytes by human complement. Finally, anti-paramyosin antibodies enhanced in vitro killing of schistosomula by normal and C4-depleted human complement. Taken together, these findings suggest that an exogenous form of S. mansoni paramyosin inhibits activation of the terminal pathway of complement and thus has an important immunomodulatory role in schistosomiasis.
Collapse
Affiliation(s)
- Jiusheng Deng
- Departments of Human Microbiology. Cell and Developmental Biology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | | | | | | |
Collapse
|
31
|
Scibek JJ, Plumb ME, Sodetz JM. Binding of human complement C8 to C9: role of the N-terminal modules in the C8 alpha subunit. Biochemistry 2002; 41:14546-51. [PMID: 12463754 DOI: 10.1021/bi026641j] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Human C8 is one of five components of the membrane attack complex of complement (MAC). It is composed of a disulfide-linked C8alpha-gamma heterodimer and a noncovalently associated C8beta chain. The C8alpha and C8beta subunits contain a pair of N-terminal modules [thrombospondin type 1 (TSP1) + low-density lipoprotein receptor class A (LDLRA)] and a pair of C-terminal modules [epidermal growth factor (EGF) + TSP1]. The middle segment of each protein is referred to as the membrane attack complex/perforin domain (MACPF). During MAC formation, C8alpha mediates binding and self-polymerization of C9 to form a pore-like structure on the membrane of target cells. In this study, the portion of C8alpha involved in binding C9 was identified using recombinant C8alpha constructs in which the N- and/or C-terminal modules were either exchanged with those from C8beta or deleted. Those constructs containing the C8alpha N-terminal TSP1 or LDLRA module together with the C8alpha MACPF domain retained the ability to bind C9 and express C8 hemolytic activity. By contrast, those containing the C8alpha MACPF domain alone or the C8alpha MACPF domain and C8alpha C-terminal modules lost this ability. These results indicate that both N-terminal modules in C8alpha have a role in forming the principal binding site for C9 and that binding may be dependent on a cooperative interaction between these modules and the C8alpha MACPF domain.
Collapse
Affiliation(s)
- Jeffery J Scibek
- Department of Chemistry and Biochemistry and School of Medicine, University of South Carolina, Columbia, South Carolina 29208, USA
| | | | | |
Collapse
|
32
|
Ortlund E, Parker CL, Schreck SF, Ginell S, Minor W, Sodetz JM, Lebioda L. Crystal structure of human complement protein C8gamma at 1.2 A resolution reveals a lipocalin fold and a distinct ligand binding site. Biochemistry 2002; 41:7030-7. [PMID: 12033936 DOI: 10.1021/bi025696i] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
C8gamma is a 22-kDa subunit of human C8, which is one of five components of the cytolytic membrane attack complex of complement (MAC). C8gamma is disulfide-linked to a C8alpha subunit that is noncovalently associated with a C8beta chain. In the present study, the three-dimensional structure of recombinant C8gamma was determined by X-ray diffraction to 1.2 A resolution. The structure displays a typical lipocalin fold forming a calyx with a distinct binding pocket that is indicative of a ligand-binding function for C8gamma. When compared to other lipocalins, the overall structure is most similar to neutrophil gelatinase associated lipocalin (NGAL), a protein released from granules of activated neutrophils. Notable differences include a much deeper binding pocket in C8gamma as well as variation in the identity and position of residues lining the pocket. In C8gamma, these residues allow ligand access to a large hydrophobic cavity at the base of the calyx, whereas corresponding residues in NGAL restrict access. This suggests the natural ligands for C8gamma and NGAL are significantly different in size. Cys40 in C8gamma, which forms the disulfide bond to C8alpha, is located in a partially disordered loop (loop 1, residues 38-52) near the opening of the calyx. Access to the calyx may be regulated by movement of this loop in response to conformational changes in C8alpha during MAC formation.
Collapse
Affiliation(s)
- Eric Ortlund
- Department of Chemistry and Biochemistry and the School of Medicine, University of South Carolina, Columbia, South Carolina 29208, USA
| | | | | | | | | | | | | |
Collapse
|
33
|
Farkas I, Baranyi L, Ishikawa Y, Okada N, Bohata C, Budai D, Fukuda A, Imai M, Okada H. CD59 blocks not only the insertion of C9 into MAC but inhibits ion channel formation by homologous C5b-8 as well as C5b-9. J Physiol 2002; 539:537-45. [PMID: 11882685 PMCID: PMC2290142 DOI: 10.1113/jphysiol.2001.013381] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Activation of the complement system on the cell surface results in the insertion of pore forming membrane attack complexes (MAC, C5b-9). In order to protect themselves from the complement attack, the cells express several regulatory molecules, including the terminal complex regulator CD59 that inhibits assembly of the large MACs by inhibiting the insertion of additional C9 molecules into the C5b-9 complex. Using the whole cell patch clamp method, we were able to measure accumulation of homologous MACs in the membrane of CD59(-) human B-cells, which formed non-selective ion channels with a total conductance of 360 +/- 24 pS as measured at the beginning of the steady-state phase of the inward currents. C5b-8 and small-size MAC (MAC containing only a single C9) can also form ion channels. Nevertheless, in CD59(+) human B-cells in spite of small-size MAC formation, an ion current could not be detected. In addition, restoring CD59 to the membrane of the CD59(-) cells inhibited the serum-evoked inward current. The ion channels formed by the small-size MAC were therefore sealed, indicating that CD59 directly interfered with the pore formation of C5b-8 as well as that of small-size C5b-9. These results offer an explanation as to why CD59-expressing cells are not leaky in spite of a buildup of homologous C5b-8 and small-size MAC. Our experiments also confirmed that ion channel inhibition by CD59 is subject to homologous restriction and that CD59 cannot block the conductivity of MAC when generated by xenogenic (rabbit) serum.
Collapse
Affiliation(s)
- Imre Farkas
- Department of Molecular Biology, Nagoya City University School of Medicine, Nagoya 467-8601, Japan
| | | | | | | | | | | | | | | | | |
Collapse
|
34
|
Sunday ME, Haley KJ, Emanuel RL, Torday JS, Asokananthan N, Sikorski KA, Tooyama I, Kimura H, Renda T, Erspamer V. Fetal alveolar epithelial cells contain [D-Ala(2)]-deltorphin I-like immunoreactivity: delta- and mu-opiate receptors mediate opposite effects in developing lung. Am J Respir Cell Mol Biol 2001; 25:447-56. [PMID: 11694450 DOI: 10.1165/ajrcmb.25.4.4072] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Opiate-like peptides can regulate many cellular functions. We now map [D-Ala(2)]deltorphin I (DADTI)-like immunoreactivity (DADTI-LI) in developing mouse lung and analyze potential functional roles. Most DADTI-LI-positive cells were alveolar cells negative for prosurfactant protein (proSP)-C immunoreactivity. Peak numbers of DADTI-LI-positive cells occurred on embryonic Day 18, decreasing postnatally. To analyze developmental effects of DADTI, e17-18 lung explants were treated with [D-Ala(2)]deltorphin II (DADTII, soluble DADTI analogue, delta-receptor-specific) versus dermorphin (mu-receptor-specific). Type II pneumocyte differentiation, assessed by [(3)H]choline incorporation into saturated phosphatidylcholine and proSP-C immunostaining, was inhibited by DADTII but stimulated by dermorphin. Cell proliferation, measured as [(3)H]-thymidine incorporation and proliferating cell nuclear antigen immunostaining, was stimulated by DADTII and inhibited by dermorphin. All effects were dose-dependent. DADTII-inhibited choline incorporation was reversed by the delta-blocker, naltrindole. Unexpectedly, DADTII-stimulated thymidine incorporation was augmented by naltrindole and reversed by naloxone (mu-blocker). Although dermorphin-stimulated choline incorporation was appropriately blocked by binaltorphimine, dermorphin-inhibited thymidine incorporation was reversed by delta, kappa-, or mu-blockers. The delta- and mu-receptor messenger RNAs occurred pre- and postnatally, whereas kappa-receptor transcripts occurred mainly prenatally. All three receptor proteins were present in epithelial and mesenchymal cells in e18 lung. Thus, DADTI-LI from proSP-C-immunonegative alveolar cells could regulate development via both direct and indirect effects involving multiple opiate receptors.
Collapse
Affiliation(s)
- M E Sunday
- Department of Pathology, Children's Hospital, Enders 909, 300 Longwood Ave., Boston, MA 02115, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
35
|
Plumb ME, Sodetz JM. An indel within the C8 alpha subunit of human complement C8 mediates intracellular binding of C8 gamma and formation of C8 alpha-gamma. Biochemistry 2000; 39:13078-83. [PMID: 11041874 DOI: 10.1021/bi001451z] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Human C8 is one of five complement components (C5b, C6, C7, C8, and C9) that interact to form the cytolytic membrane attack complex, or MAC. It is an oligomeric protein composed of three subunits (C8alpha, C8beta, C8gamma) that are products of different genes. In C8 from serum, these are arranged as a disulfide-linked C8alpha-gamma dimer that is noncovalently associated with C8beta. In this study, the site on C8alpha that mediates intracellular binding of C8gamma to form C8alpha-gamma was identified. From a comparative analysis of indels (insertions/deletions) in C8alpha and its structural homologues C8beta, C6, C7, and C9, it was determined that C8alpha contains a unique insertion (residues 159-175), which includes Cys(164) that forms the disulfide bond to C8gamma. Incorporation of this sequence into C8beta and coexpression of the resulting construct (iC8beta) with C8gamma produced iC8beta-gamma, an atypical disulfide-linked dimer. In related experiments, C8gamma was shown to bind noncovalently to mutant forms of C8alpha and iC8beta in which Cys(164)-->Gly(164) substitutions were made. In addition, C8gamma bound specifically to an immobilized synthetic peptide containing the mutant indel sequence. Together, these results indicate (a) intracellular binding of C8gamma to C8alpha is mediated principally by residues contained within the C8alpha indel, (b) binding is not strictly dependent on Cys(164), and (c) C8gamma must contain a complementary binding site for the C8alpha indel.
Collapse
Affiliation(s)
- M E Plumb
- Department of Chemistry and Biochemistry and the School of Medicine, University of South Carolina, Columbia, South Carolina 29208, USA
| | | |
Collapse
|
36
|
Duttaroy A, Shen J, Shah S, Chen B, Sehba F, Carroll J, Yoburn BC. Opioid receptor upregulation in mu-opioid receptor deficient CXBK and outbred Swiss Webster mice. Life Sci 1999; 65:113-23. [PMID: 10416817 DOI: 10.1016/s0024-3205(99)00228-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Chronic in vivo treatment with opioid antagonists increases opioid receptor density and the potency of opioid agonists without altering receptor mRNA levels. To determine if basal receptor density affects opioid receptor upregulation, we examined the effect of chronic naltrexone treatment on mu-opioid receptor density and mRNA in two mice strains that differ in mu-opioid receptor density. CXBK mice (mu-opioid receptor deficient) and outbred Swiss Webster mice were implanted s.c. with a placebo or 15 mg naltrexone pellet for 8 days, the pellets removed and 24 hr later opioid receptor density (mu, delta) and receptor mRNA level (mu) determined in whole brain; or morphine dose-response studies conducted. In placebo-treated CXBK mice, mu-opioid receptor density was approximately 40% less than in Swiss Webster mice, although mu-opioid receptor mRNA abundance was similar in both strains. In placebo-treated CXBK mice, morphine potency was approximately 6-fold less than Swiss Webster mice. Naltrexone treatment increased morphine potency (1.7-fold) and mu- (approximately 90%) and delta- (approximately 20-40%) opioid receptor density in CXBK and Swiss Webster mouse brain similarly. Mu-opioid receptor mRNA was unchanged by naltrexone treatment in either strain. There was no difference in the basal or naltrexone-treated whole brain G(i alpha2) protein levels in CXBK or Swiss Webster mouse. These data indicate that a deficiency in mu-opioid receptors does not alter the regulation of opioid receptors by opioid antagonists in vivo, and suggest that adaptive responses to chronic opioid antagonist treatment are independent of opioid receptor density.
Collapse
MESH Headings
- Analgesics/pharmacology
- Animals
- Brain Chemistry/drug effects
- Enkephalin, D-Penicillamine (2,5)-
- Enkephalins/metabolism
- Gene Expression
- Male
- Mice/physiology
- Mice, Mutant Strains/physiology
- Naltrexone/pharmacology
- Narcotic Antagonists/pharmacology
- Receptors, Opioid/physiology
- Receptors, Opioid, delta/agonists
- Receptors, Opioid, mu/deficiency
- Receptors, Opioid, mu/genetics
- Up-Regulation
Collapse
Affiliation(s)
- A Duttaroy
- Department of Pharmaceutical Sciences, College of Pharmacy and Allied Health Professions, St. John's University, Queens, NY 11439, USA
| | | | | | | | | | | | | |
Collapse
|
37
|
Plumb ME, Scibek JJ, Barber TD, Dunlap RJ, Platteborze PL, Sodetz JM. Chimeric and truncated forms of human complement protein C8 alpha reveal binding sites for C8 beta and C8 gamma within the membrane attack complex/perforin region. Biochemistry 1999; 38:8478-84. [PMID: 10387094 DOI: 10.1021/bi9904858] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Human C8 is one of five components of the membrane attack complex of complement. It is an oligomeric protein composed of three subunits (C8 alpha, C8 beta, and C8 gamma) that are derived from different genes. C8 alpha and C8 beta are homologous and both contain a pair of tandemly arranged N-terminal modules [thrombospondin type 1 (TSP1) + low-density lipoprotein receptor class A (LDLRA)], an extended middle segment referred to as the membrane attack complex/perforin region (MACPF), and a pair of C-terminal modules [epidermal growth factor (EGF) + TSP1]. During biosynthetic processing, C8 alpha and C8 gamma associate to form a disulfide-linked dimer (C8 alpha-gamma) that binds to C8 beta through a site located on C8 alpha. In this study, the location of binding sites for C8 beta and C8 gamma and the importance of the modules in these interactions were investigated by use of chimeric and truncated forms of C8 alpha in which module pairs were either exchanged for those in C8 beta or deleted. Results show that exchange or deletion of one or both pairs of modules does not abrogate the ability of C8 alpha to form a disulfide-linked dimer when coexpressed with C8 gamma in COS cells. Furthermore, each chimeric and truncated form of C8 alpha-gamma retains the ability to bind C8 beta; however, only those containing the TSP1 + LDLRA modules from C8 alpha are hemolytically active. These results indicate that binding sites for C8 beta and C8 gamma reside within the MACPF region of C8 alpha and that interaction with either subunit is not dependent on the modules. They also suggest that the N-terminal modules in C8 alpha are important for C9 binding and/or expression of C8 activity.
Collapse
Affiliation(s)
- M E Plumb
- Department of Chemistry and Biochemistry, School of Medicine, University of South Carolina, Columbia 29208, USA
| | | | | | | | | | | |
Collapse
|
38
|
Winkler A, Buzas B, Siems WE, Heder G, Cox BM. Effect of Ethanol Drinking on the Gene Expression of Opioid Receptors, Enkephalinase, and Angiotensin-Converting Enzyme in Two Inbred Mice Strains. Alcohol Clin Exp Res 1998. [DOI: 10.1111/j.1530-0277.1998.tb03907.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
|
39
|
Schreck SF, Plumb ME, Platteborze PL, Kaufman KM, Michelotti GA, Letson CS, Sodetz JM. Expression and Characterization of Recombinant Subunits of Human Complement Component C8: Further Analysis of the Function of C8α and C8γ. THE JOURNAL OF IMMUNOLOGY 1998. [DOI: 10.4049/jimmunol.161.1.311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
Human C8 is composed of three nonidentical subunits (C8α, C8β, and C8γ) that are encoded in separate genes. In C8 isolated from serum, these are arranged as a disulfide-linked C8α-γ dimer that is noncovalently associated with C8β. In this study, a recombinant form of C8α-γ was expressed independently of C8β in insect cells and COS-7 cells and was shown to be equivalent to serum-derived C8α-γ with respect to its ability to combine with C8β and form functional C8. Also expressed separately were mutant (mut) forms of C8α and C8γ in which the single interchain disulfide bond was eliminated. MutC8α exhibited the ability to combine with C8β and express hemolytic activity, although at a lower level than human C8. Addition of purified mutC8γ increased this activity, presumably by binding to mutC8α. A possible role for C8γ as a retinol binding protein was also investigated. Absorbance spectroscopy and fluorescence emission and quenching revealed no specific binding of retinol to mutC8γ. Together, these results indicate that 1) the biosynthesis and secretion of C8α-γ is not dependent on C8β, which is consistent with in vivo observations in C8β-deficient humans; 2) C8α can be synthesized independently of C8γ; therefore, protection of C8α from premature membrane interactions during biosynthetic processing is not a likely function of C8γ; 3) C8γ enhances but is not required for expression of C8 activity; and 4) C8γ does not bind retinol; therefore, it cannot function as a retinol transport protein.
Collapse
Affiliation(s)
- Steven F. Schreck
- Department of Chemistry and Biochemistry and School of Medicine, University of South Carolina, Columbia, SC 29208
| | - Mnason E. Plumb
- Department of Chemistry and Biochemistry and School of Medicine, University of South Carolina, Columbia, SC 29208
| | - Peter L. Platteborze
- Department of Chemistry and Biochemistry and School of Medicine, University of South Carolina, Columbia, SC 29208
| | - Kenneth M. Kaufman
- Department of Chemistry and Biochemistry and School of Medicine, University of South Carolina, Columbia, SC 29208
| | - Gregory A. Michelotti
- Department of Chemistry and Biochemistry and School of Medicine, University of South Carolina, Columbia, SC 29208
| | - Carole S. Letson
- Department of Chemistry and Biochemistry and School of Medicine, University of South Carolina, Columbia, SC 29208
| | - James M. Sodetz
- Department of Chemistry and Biochemistry and School of Medicine, University of South Carolina, Columbia, SC 29208
| |
Collapse
|
40
|
Zhao XJ, Zhao J, Zhou Q, Sims PJ. Identity of the residues responsible for the species-restricted complement inhibitory function of human CD59. J Biol Chem 1998; 273:10665-71. [PMID: 9553129 DOI: 10.1074/jbc.273.17.10665] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The membrane-anchored glycoprotein CD59 inhibits assembly of the C5b-9 membrane attack complex (MAC) of human complement. This inhibitory function of CD59 is markedly selective for MAC assembled from human complement components C8 and C9, and CD59 shows little inhibitory function toward MAC assembled from rabbit and many other non-primate species. We have used this species selectivity of CD59 to identify the residues regulating its complement inhibitory function: cDNA of rabbit CD59 was cloned and used to express human/rabbit CD59 chimeras in murine SV-T2 cells. Plasma membrane expression of each CD59 chimera was quantified by use of a 5'-TAG peptide epitope, and each construct was tested for its ability to inhibit assembly of functional MAC from human versus rabbit C8 and C9. These experiments revealed that the species selectivity of CD59 is entirely determined by sequence contained between residues 42 and 58 of the human CD59 polypeptide, whereas chimeric substitution outside this peptide segment has little effect on the MAC inhibitory function of CD59. Substitution of human CD59 residues 42-58 into rabbit CD59 resulted in a molecule that was functionally indistinguishable from native human CD59, whereas the complementary construct (corresponding residues of rabbit CD59 substituted into human CD59) was functionally indistinguishable from rabbit CD59. Based on the solved solution structure of CD59, these data suggest that selectivity for human C8 and C9 resides in a cluster of closely spaced side chains on the surface of CD59 contributed by His44, Asn48, Asp49, Thr51, Thr52, Arg55, and Glu58 of the polypeptide.
Collapse
Affiliation(s)
- X J Zhao
- Blood Research Institute, the Blood Center, Milwaukee, Wisconsin 53201-2178, USA
| | | | | | | |
Collapse
|
41
|
Suzuki H, Yamaji N, Egashira A, Yasunaga K, Sugita Y, Masuho Y. Effect of the sugar chain of soluble recombinant CD59 on complement inhibitory activity. FEBS Lett 1996; 399:272-6. [PMID: 8985161 DOI: 10.1016/s0014-5793(96)01340-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
A soluble recombinant CD59#77 (rCD59#77), consisting of 77 amino acids starting from the N terminus of membrane-bound CD59, was prepared using a gene expression system in CHO cells. The rCD59#77 preparation was composed of glycosylated and non-glycosylated forms (G and NG forms). Unexpectedly, NG form was 7 times more potent than G form in complement inhibitory activity. Postulating that sialic acids on G-form molecules make it difficult for rCD59#77 to access nascent membrane attack complexes on the cell surface, the sialic acids were removed by neuraminidase treatment. However, the inhibitory activity was not changed. Next, one of two putative N-glycosylation sites was mutated by substituting Gln18 for Asn18. The mutant, designated rCD59#77(N/Q), had no sugar moiety and was as active as the NG form of rCD59#77. These results suggest that the bulky sugar moiety at Asn18 is not necessary for the complement-inhibitory activity of rCD59 and actually hampers that function.
Collapse
Affiliation(s)
- H Suzuki
- Molecular Medicine Research Laboratory, Yamanouchi Pharmaceutical Co., Ltd., Tsukuba City, Ibaraki, Japan.
| | | | | | | | | | | |
Collapse
|
42
|
Piros ET, Hales TG, Evans CJ. Functional analysis of cloned opioid receptors in transfected cell lines. Neurochem Res 1996; 21:1277-85. [PMID: 8947917 DOI: 10.1007/bf02532368] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Opioids modulate numerous central and peripheral processes including pain perception neuroendocrine secretion and the immune response. The opioid signal is transduced from receptors through G proteins to various different effectors. Heterogeneity exists at all levels of the transduction process. There are numerous endogenous ligands with differing selectivities for at least three distinct opioid receptors (mu, delta, kappa). G proteins activated by opioid receptors are generally of the pertussis toxin-sensitive Gi/Go class, but there are also opioid actions that are thought to involve Gq and cholera toxin-sensitive G proteins. To further complicate the issue, the actions of opioid receptors may be mediated by G-protein alpha subunits and/or beta gamma subunits. Subsequent to G protein activation several effectors are known to orchestrate the opioid signal. For example activation of opioid receptors increases phosphatidyl inositol turnover, activates K+ channels and reduces adenylyl cyclase and Ca2+ channel activities. Each of these effectors shows considerable heterogeneity. In this review we examine the opioid signal transduction mechanism. Several important questions arise: Why do opioid ligands with similar binding affinities have different potencies in functional assays? To which Ca2+ channel subtypes do opioid receptors couple? Do opioid receptors couple to Ca2+ channels through direct G protein interactions? Does the opioid-induced inhibition of vesicular release occur through modulation of multiple effectors? We are attempting to answer these questions by expressing cloned opioid receptors in GH3 cells. Using this well characterized system we can study the entire opioid signal transduction process from ligand-receptor interaction to G protein-effector coupling and subsequent inhibition of vesicular release.
Collapse
MESH Headings
- Animals
- Cell Line
- Cyclic AMP/metabolism
- GTP-Binding Proteins/metabolism
- Humans
- Inositol Phosphates/metabolism
- Models, Biological
- Narcotics/pharmacology
- Receptors, Opioid/biosynthesis
- Receptors, Opioid/physiology
- Receptors, Opioid, delta/biosynthesis
- Receptors, Opioid, delta/physiology
- Receptors, Opioid, kappa/biosynthesis
- Receptors, Opioid, kappa/physiology
- Receptors, Opioid, mu/biosynthesis
- Receptors, Opioid, mu/physiology
- Recombinant Proteins/biosynthesis
- Signal Transduction
- Transfection/methods
Collapse
Affiliation(s)
- E T Piros
- Department of Psychiatry and Biobehavioral Sciences, University of California, School of Medicine, Los Angeles 90095, USA
| | | | | |
Collapse
|
43
|
Li X, Keith DE, Evans CJ. Mu opioid receptor-like sequences are present throughout vertebrate evolution. J Mol Evol 1996; 43:179-84. [PMID: 8703083 DOI: 10.1007/bf02338825] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/09/2023]
Abstract
The sequence of the mu opioid receptor is highly conserved among human, rat, and mouse. In order to gain insights into the evolution of the mu opioid receptor, polymerase chain reaction (PCR) was used to screen genomic DNA from a number of different species using degenerate oligonucleotides which recognize a highly conserved region. DNA was assayed from representative species of both the protostome and deuterostome branches of the metazoan phylogenetic tree. Mu opioid receptor-like sequences were found in all vertebrate species that were analyzed. These species included bovine, chicken, bullfrog, striped bass, thresher shark, and Pacific hagfish. However, no mu opioid receptor-like sequences were detected from protostomes or from any invertebrates. The PCR results demonstrate that the region of the mu opioid receptor gene between the first intracellular loop and the third transmembrane domain (TM3) has been highly conserved during evolution and that mu opioid receptor-like sequences are present in the earliest stages of vertebrate evolution. Additional opioid receptor-like sequence was obtained from mRNA isolated from Pacific hagfish brain using rapid amplification of cDNA ends (RACE). The sequence of the Pacific hagfish was most homologous with the human mu opioid receptor (72% at the amino acid level between intracellular loop 1 and transmembrane domain 6) although over the same region high homology was also observed with the delta opioid receptor (69%), the kappa receptor (63%), and opioid receptor-like (ORL1) (59%). The hagfish sequence showed low conservation with the mammalian opioid receptors in the first and second extracellular loops but high conservation in the transmembrane and intracellular domains.
Collapse
Affiliation(s)
- X Li
- Department of Psychiatry and Biobehavioral Sciences, School of Medicine, University of California, Los Angeles, 760 Westwood Plaza, Los Angeles, CA 90024-1759, USA
| | | | | |
Collapse
|
44
|
Husler T, Lockert DH, Sims PJ. Role of a disulfide-bonded peptide loop within human complement C9 in the species-selectivity of complement inhibitor CD59. Biochemistry 1996; 35:3263-9. [PMID: 8605162 DOI: 10.1021/bi952862w] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
CD59 antigen is a membrane glycoprotein that inhibits the activity of the C9 component of the C5b-9 membrane attack complex (MAC), thereby protecting human cells from lysis by human complement. The complement-inhibitory activity of CD59 is species-selective, and is most effective toward C9 derived from human or other primate plasma. The species-selective activity of CD59 was recently used to map the segment of human C9 that is recognized by this MAC inhibitor, using recombinant rabbit/human C9 chimeras that retain lytic function within the MAC [Husler, T., Lockert, D. H., Kaufman, K. M., Sodetz, J. M., & Sims, P. J. (1995) J. Biol. Chem. 270,3483-3486]. These experiments suggested that the CD59 recognition domain was contained between residues 334 and 415 in human C9. By analyzing the species-selective lytic activity of recombinant C9 with chimeric substitutions internal to this segment, we now demonstrate that the site in human C9 uniquely recognized by CD59 is centered on those residues contained between C9 Cys359/Cys384, with an additional contribution by residues C-terminal to this segment. Consistent with its role as a CD59 recognition domain, CD59 specifically bound a human C9-derived peptide corresponding to residues 359-384, and antibody (Fab) raised against this C9-derived peptide inhibited the lytic activity of human MAC. Mutant human C9 in which Ala was substituted for Cys359/384 was found to express normal lytic activity and to be fully inhibited by CD59. This suggests that the intrachain Cys359/Cys384 disulfide bond within C9 is not required to maintain the conformation of this segment of C9 for interaction with CD59.
Collapse
Affiliation(s)
- T Husler
- Blood Research Institute, Blood Center of Southeastern Wisconsin, Milwaukee, 53233, USA
| | | | | |
Collapse
|
45
|
Petranka J, Zhao J, Norris J, Tweedy NB, Ware RE, Sims PJ, Rosse WF. Structure-function relationships of the complement regulatory protein, CD59. Blood Cells Mol Dis 1996; 22:281-96. [PMID: 9075580 DOI: 10.1006/bcmd.1996.0111] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
CD59 (membrane inhibitor of reactive lysis, protectin) is a membrane protein whose functions include the inhibition of the insertion of the ninth component of complement into the target membrane. It belongs to a superfamily of proteins including Ly-6, elapid snake venom toxins, and urokinase receptor (UPAR); the members of the superfamily have a similar structure that includes four (in mammals five) disulfide bridges that maintain a three-dimensional conformation consisting of a central core, three finger-like "loops" extending from it and a small loop near the coboxyl end. We have used site directed mutagenesis to explore three aspects of the structure of CD59: 1) the role of the disulfide bridges in expression and function of the molecule; 2) the location of epitopes reacting with monoclonal antibodies to the molecule; and 3) the parts of the molecule that are critical to its function in inhibiting complement lysis. Mutant molecules in which the disulfides maintaining the finger-like loops (Cys3-Cys26, Cys19-Cys39, and Cys45-Cys63) were removed were not expressed on the cell surface. The mutation of the disulfide (Cys6-Cys13) resulted in no change in expression or function. The mutation of Cys64-Cys69 maintaining the small loop resulted in an expressed molecule with increased functional activity. The major epitope for 6 of 7 monoclonal antibodies was centered on Arg53 as the mutation 53Arg-->Ser resulted in a loss of interaction with these antibodies, as did the deletion of four nearby residues (Leu54-Asn57). The alteration 55Arg-->Ser resulted in loss of reactivity for some but not other antibodies. The reactivity with one monoclonal antibody, H19, was abrogated by the mutations 61Tyr-->Gly and 61Tyr-->Ala. Functional activity of the molecule was not adversely altered by mutations in the first and second loops; however, the 61Tyr-->Gly mutation was non-functional. The mutation of 61Tyr-->His diminished function but changes 61Tyr-->Ala and 61Tyr-->Phe had no effect on function. We conclude that the functional site of CD59 is located in this region of the molecule.
Collapse
Affiliation(s)
- J Petranka
- Department of Medicine, Duke University Medical Center, Durham, NC 2710, USA
| | | | | | | | | | | | | |
Collapse
|