151
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Clare DK, Siebert CA, Hecksel C, Hagen C, Mordhorst V, Grange M, Ashton AW, Walsh MA, Grünewald K, Saibil HR, Stuart DI, Zhang P. Electron Bio-Imaging Centre (eBIC): the UK national research facility for biological electron microscopy. Acta Crystallogr D Struct Biol 2017; 73:488-495. [PMID: 28580910 PMCID: PMC5458490 DOI: 10.1107/s2059798317007756] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Accepted: 05/24/2017] [Indexed: 12/13/2022] Open
Abstract
The recent resolution revolution in cryo-EM has led to a massive increase in demand for both time on high-end cryo-electron microscopes and access to cryo-electron microscopy expertise. In anticipation of this demand, eBIC was set up at Diamond Light Source in collaboration with Birkbeck College London and the University of Oxford, and funded by the Wellcome Trust, the UK Medical Research Council (MRC) and the Biotechnology and Biological Sciences Research Council (BBSRC) to provide access to high-end equipment through peer review. eBIC is currently in its start-up phase and began by offering time on a single FEI Titan Krios microscope equipped with the latest generation of direct electron detectors from two manufacturers. Here, the current status and modes of access for potential users of eBIC are outlined. In the first year of operation, 222 d of microscope time were delivered to external research groups, with 95 visits in total, of which 53 were from unique groups. The data collected have generated multiple high- to intermediate-resolution structures (2.8-8 Å), ten of which have been published. A second Krios microscope is now in operation, with two more due to come online in 2017. In the next phase of growth of eBIC, in addition to more microscope time, new data-collection strategies and sample-preparation techniques will be made available to external user groups. Finally, all raw data are archived, and a metadata catalogue and automated pipelines for data analysis are being developed.
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Affiliation(s)
- Daniel K. Clare
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, England
| | - C. Alistair Siebert
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, England
| | - Corey Hecksel
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, England
| | - Christoph Hagen
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, England
| | - Valerie Mordhorst
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, England
| | - Michael Grange
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, England
| | - Alun W. Ashton
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, England
| | - Martin A. Walsh
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, England
- Research Complex at Harwell, Harwell Science and Innovation Campus, Didcot OX11 0FA, England
| | - Kay Grünewald
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, England
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, England
| | - Helen R. Saibil
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, England
- Crystallography, Institute for Structural and Molecular Biology, Birkbeck College, Malet Street, London WC1E 7HX, England
| | - David I. Stuart
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, England
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, England
| | - Peijun Zhang
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, England
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, England
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152
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Cernoch M, Viklicky O. Complement in Kidney Transplantation. Front Med (Lausanne) 2017; 4:66. [PMID: 28611987 PMCID: PMC5447724 DOI: 10.3389/fmed.2017.00066] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Accepted: 05/09/2017] [Indexed: 12/12/2022] Open
Abstract
The complement system is considered to be an important part of innate immune system with a significant role in inflammation processes. The activation can occur through classical, alternative, or lectin pathway, resulting in the creation of anaphylatoxins C3a and C5a, possessing a vast spectrum of immune functions, and the assembly of terminal complement cascade, capable of direct cell lysis. The activation processes are tightly regulated; inappropriate activation of the complement cascade plays a significant role in many renal diseases including organ transplantation. Moreover, complement cascade is activated during ischemia/reperfusion injury processes and influences delayed graft function of kidney allografts. Interestingly, complement system has been found to play a role in both acute cellular and antibody-mediated rejections and thrombotic microangiopathy. Therefore, complement system may represent an interesting therapeutical target in kidney transplant pathologies.
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Affiliation(s)
- Marek Cernoch
- Transplant Laboratory, Transplant Center, Institute for Clinical and Experimental Medicine, Prague, Czechia
| | - Ondrej Viklicky
- Transplant Laboratory, Transplant Center, Institute for Clinical and Experimental Medicine, Prague, Czechia.,Department of Nephrology, Transplant Center, Institute for Clinical and Experimental Medicine, Prague, Czechia
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153
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Berkowicz SR, Giousoh A, Bird PI. Neurodevelopmental MACPFs: The vertebrate astrotactins and BRINPs. Semin Cell Dev Biol 2017; 72:171-181. [PMID: 28506896 DOI: 10.1016/j.semcdb.2017.05.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2016] [Revised: 04/27/2017] [Accepted: 05/11/2017] [Indexed: 02/06/2023]
Abstract
Astrotactins (ASTNs) and Bone morphogenetic protein/retinoic acid inducible neural-specific proteins (BRINPs) are two groups of Membrane Attack Complex/Perforin (MACPF) superfamily proteins that show overlapping expression in the developing and mature vertebrate nervous system. ASTN(1-2) and BRINP(1-3) genes are found at conserved loci in humans that have been implicated in neurodevelopmental disorders (NDDs). Here we review the tissue distribution and cellular localization of these proteins, and discuss recent studies that provide insight into their structure and interactions. We highlight the genetic relationships and co-expression of Brinps and Astns; and review recent knock-out mouse phenotypes that indicate a possible overlap in protein function between ASTNs and BRINPs.
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Affiliation(s)
- Susan R Berkowicz
- Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, 3800, Australia.
| | - Aminah Giousoh
- Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, 3800, Australia
| | - Phillip I Bird
- Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, 3800, Australia
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154
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Leung C, Hodel AW, Brennan AJ, Lukoyanova N, Tran S, House CM, Kondos SC, Whisstock JC, Dunstone MA, Trapani JA, Voskoboinik I, Saibil HR, Hoogenboom BW. Real-time visualization of perforin nanopore assembly. NATURE NANOTECHNOLOGY 2017; 12:467-473. [PMID: 28166206 DOI: 10.1038/nnano.2016.303] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 12/29/2016] [Indexed: 06/06/2023]
Abstract
Perforin is a key protein of the vertebrate immune system. Secreted by cytotoxic lymphocytes as soluble monomers, perforin can self-assemble into oligomeric pores of 10-20 nm inner diameter in the membranes of virus-infected and cancerous cells. These large pores facilitate the entry of pro-apoptotic granzymes, thereby rapidly killing the target cell. To elucidate the pathways of perforin pore assembly, we carried out real-time atomic force microscopy and electron microscopy studies. Our experiments reveal that the pore assembly proceeds via a membrane-bound prepore intermediate state, typically consisting of up to approximately eight loosely but irreversibly assembled monomeric subunits. These short oligomers convert to more closely packed membrane nanopore assemblies, which can subsequently recruit additional prepore oligomers to grow the pore size.
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Affiliation(s)
- Carl Leung
- London Centre for Nanotechnology, University College London, London WC1H 0AH, UK
- Department of Crystallography/Biological Sciences, Institute of Structural and Molecular Biology, Birkbeck College, London WC1E 7HX, 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
| | - Amelia J Brennan
- Killer Cell Biology Laboratory, Peter MacCallum Cancer Centre, East Melbourne, Victoria 3000, Australia
| | - Natalya Lukoyanova
- Department of Crystallography/Biological Sciences, Institute of Structural and Molecular Biology, Birkbeck College, London WC1E 7HX, UK
| | - Sharon Tran
- Killer Cell Biology Laboratory, Peter MacCallum Cancer Centre, East Melbourne, Victoria 3000, Australia
| | - Colin M House
- Cancer Cell Death Laboratory, Peter MacCallum Cancer Centre, East Melbourne, Victoria 3000, Australia
| | - Stephanie C Kondos
- Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Victoria 3800, Australia
| | - James C Whisstock
- Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Victoria 3800, Australia
- The ARC Centre of Excellence in Advanced Molecular Imaging, Monash University, Melbourne, Victoria 3800, Australia
| | - Michelle A Dunstone
- Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Victoria 3800, Australia
- The ARC Centre of Excellence in Advanced Molecular Imaging, Monash University, Melbourne, Victoria 3800, Australia
- Department of Microbiology, Monash University, Melbourne, Victoria 3800, Australia
| | - Joseph A Trapani
- Cancer Cell Death Laboratory, Peter MacCallum Cancer Centre, East Melbourne, Victoria 3000, Australia
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Ilia Voskoboinik
- Killer Cell Biology Laboratory, Peter MacCallum Cancer Centre, East Melbourne, Victoria 3000, Australia
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Helen R Saibil
- Department of Crystallography/Biological Sciences, Institute of Structural and Molecular Biology, Birkbeck College, London WC1E 7HX, 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
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155
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Mizuno M, Suzuki Y, Ito Y. Complement regulation and kidney diseases: recent knowledge of the double-edged roles of complement activation in nephrology. Clin Exp Nephrol 2017; 22:3-14. [DOI: 10.1007/s10157-017-1405-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 03/14/2017] [Indexed: 12/28/2022]
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156
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Survival of Carbapenem-Resistant Klebsiella pneumoniae Sequence Type 258 in Human Blood. Antimicrob Agents Chemother 2017; 61:AAC.02533-16. [PMID: 28115349 DOI: 10.1128/aac.02533-16] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Accepted: 01/18/2017] [Indexed: 12/14/2022] Open
Abstract
Klebsiella pneumoniae is a prominent cause of nosocomial infections worldwide. Bloodstream infections caused by carbapenem-resistant K. pneumoniae, including the epidemic lineage known as multilocus sequence type 258 (ST258), are difficult to treat, and the rate of mortality from such infections is high. Thus, it is imperative that we gain a better understanding of host defense against this pathogen as a step toward developing novel therapies. Here we tested the hypothesis that the resistance of ST258 to bactericidal components of human blood, such as serum complement, is linked to virulence capacity in the context of bacteremia. There was significant variance in the survival of ST258 clinical isolates in heparinized human blood or normal human serum. The rate of survival of ST258 isolates in human blood was, in general, similar to that in normal human serum, suggesting a prominent role for complement (rather than leukocytes) in the healthy host defense against ST258 isolates and related organisms. Indeed, deposition of serum complement-the C5b to C9 (C5b-C9) membrane attack complex-onto the surface of ST258 isolates accompanied serum bactericidal activity. Human serum treated with pharmacological inhibitors of complement, depleted of antibody, or heated at 56°C for 30 min had significantly reduced or absent bactericidal activity. In contrast to heparinized blood from humans, that from BALB/c mice lacked bactericidal activity toward the ST258 isolates tested, but the virulence of these ST258 isolates in a mouse bacteremia model was inexplicably limited. Our data highlight the importance of the complement system in host defense against ST258 bacteremia, and we propose that there is the potential to enhance complement-mediated bactericidal activity using an antibody-based approach.
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157
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Franc V, Yang Y, Heck AJR. Proteoform Profile Mapping of the Human Serum Complement Component C9 Revealing Unexpected New Features of N-, O-, and C-Glycosylation. Anal Chem 2017; 89:3483-3491. [PMID: 28221766 PMCID: PMC5362742 DOI: 10.1021/acs.analchem.6b04527] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
![]()
The human complement
C9 protein (∼65 kDa) is a member of
the complement pathway. It plays an essential role in the membrane
attack complex (MAC), which forms a lethal pore on the cellular surface
of pathogenic bacteria. Here, we charted in detail the structural
microheterogeneity of C9 purified from human blood serum, using an
integrative workflow combining high-resolution native mass spectrometry
and (glyco)peptide-centric proteomics. The proteoform profile of C9
was acquired by high-resolution native mass spectrometry, which revealed
the co-occurrence of ∼50 distinct mass spectrometry (MS) signals.
Subsequent peptide-centric analysis, through proteolytic digestion
of C9 and liquid chromatography (LC)-tandem mass spectrometry (MS/MS)
measurements of the resulting peptide mixtures, provided site-specific
quantitative profiles of three different types of C9 glycosylation
and validation of the native MS data. Our study provides a detailed
specification, validation, and quantification of 15 co-occurring C9
proteoforms and the first direct experimental evidence of O-linked glycans in the N-terminal region.
Additionally, next to the two known glycosylation sites, a third novel,
albeit low abundant, N-glycosylation site on C9 is
identified, which surprisingly does not possess the canonical N-glycosylation sequence N-X-S/T. Our data also reveal a
binding of up to two Ca2+ ions to C9. Mapping all detected
and validated sites of modifications on a structural model of C9,
as present in the MAC, hints at their putative roles in pore formation
or receptor interactions. The applied methods herein represent a powerful
tool for the unbiased in-depth analysis of plasma proteins and may
advance biomarker discovery, as aberrant glycosylation profiles may
be indicative of the pathophysiological state of the patients.
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Affiliation(s)
- Vojtech Franc
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, University of Utrecht , Padualaan 8, 3584 CH Utrecht, The Netherlands.,Netherlands Proteomics Center , Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Yang Yang
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, University of Utrecht , Padualaan 8, 3584 CH Utrecht, The Netherlands.,Netherlands Proteomics Center , Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Albert J R Heck
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, University of Utrecht , Padualaan 8, 3584 CH Utrecht, The Netherlands.,Netherlands Proteomics Center , Padualaan 8, 3584 CH Utrecht, The Netherlands
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158
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Cleavage of DFNA5 by caspase-3 during apoptosis mediates progression to secondary necrotic/pyroptotic cell death. Nat Commun 2017; 8:14128. [PMID: 28045099 PMCID: PMC5216131 DOI: 10.1038/ncomms14128] [Citation(s) in RCA: 939] [Impact Index Per Article: 134.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Accepted: 11/04/2016] [Indexed: 12/29/2022] Open
Abstract
Apoptosis is a genetically regulated cell suicide programme mediated by activation of the effector caspases 3, 6 and 7. If apoptotic cells are not scavenged, they progress to a lytic and inflammatory phase called secondary necrosis. The mechanism by which this occurs is unknown. Here we show that caspase-3 cleaves the GSDMD-related protein DFNA5 after Asp270 to generate a necrotic DFNA5-N fragment that targets the plasma membrane to induce secondary necrosis/pyroptosis. Cells that express DFNA5 progress to secondary necrosis, when stimulated with apoptotic triggers such as etoposide or vesicular stomatitis virus infection, but disassemble into small apoptotic bodies when DFNA5 is deleted. Our findings identify DFNA5 as a central molecule that regulates apoptotic cell disassembly and progression to secondary necrosis, and provide a molecular mechanism for secondary necrosis. Because DFNA5-induced secondary necrosis and GSDMD-induced pyroptosis are dependent on caspase activation, we propose that they are forms of programmed necrosis. DFNA5 is related to the caspase-dependent pyroptosis inducer gasdermin D. Here the authors find that DFNA5 is cleaved by caspase 3 and show this cleavage skews cells away from apoptosis into secondary necrosis, a form of cell death characterized by membrane ballooning similar to pyroptosis.
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159
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Yang CY, Phillips JG, Stuckey JA, Bai L, Sun H, Delproposto J, Brown WC, Chinnaswamy K. Buried Hydrogen Bond Interactions Contribute to the High Potency of Complement Factor D Inhibitors. ACS Med Chem Lett 2016; 7:1092-1096. [PMID: 27994744 DOI: 10.1021/acsmedchemlett.6b00299] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 09/13/2016] [Indexed: 01/16/2023] Open
Abstract
Aberrant activation of the complement system is associated with diseases, including paroxysmal nocturnal hemoglobinuria and age-related macular degeneration. Complement factor D is the rate-limiting enzyme for activating the alternative pathway in the complement system. Recent development led to a class of potent amide containing pyrrolidine derived factor D inhibitors. Here, we used biochemical enzymatic and biolayer interferometry assays to demonstrate that the amide group improves the inhibitor potency by more than 80-fold. Our crystal structures revealed buried hydrogen bond interactions are important. Molecular orbital analysis from quantum chemistry calculations dissects the chemical groups participating in these interactions. Free energy calculation supports the differential contributions of the amide group to the binding affinities of these inhibitors. Cell-based hemolysis assay confirmed these compounds inhibit factor D mediated complement activation via the alternative pathway. Our study highlights the important interactions contributing to the high potency of factor D inhibitors reported recently.
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Affiliation(s)
| | - James G. Phillips
- Department
of Translational Hematology and Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, Ohio 44195, United States
| | | | | | - Haiying Sun
- Jiansu
Key Laboratory of Drug Design and Optimization, Department of Medicinal
Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing 210009, China
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160
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Abstract
The complement system is an important part of the innate and adaptive immune systems. Originally characterized as a single serum component contributing to the killing of bacteria, we now know that there are close to sixty complement proteins, multiple activation pathways and a wide range of effector functions mediated by complement. The system plays a critical role in host defense against bacteria, viruses, fungi and other pathogens. However, inappropriate complement activation contributes to the pathophysiology of autoimmune diseases and many inflammatory syndromes. Over the last several decades, therapeutic approaches to inhibit complement activation at various steps in the pathways have met with initial success, particularly at the level of the terminal pathway. This success, combined with insight from animal model studies, has lead to an unprecedented effort by biotech and pharmaceutical companies to begin developing complement inhibitors. As a result, complement has been brought for the first time to the attention of pharmacologists, toxicologists, project managers and others in the drug development industry, as well as those in the investment world. The purpose of this primer is to provide a broad overview of complement immunobiology to help those new to complement understand the rationale behind the current therapeutic directions and the investment potential of these new therapeutics.
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Affiliation(s)
- Scott R Barnum
- Department of Microbiology, University of Alabama at Birmingham, 845 19th St. S., BBRB/744, Birmingham, AL 35294, United States; Department of Neurology, University of Alabama at Birmingham, 845 19th St. S., BBRB/744, Birmingham, AL 35294, United States.
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161
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The Highly Evolvable Antibody Fc Domain. Trends Biotechnol 2016; 34:895-908. [DOI: 10.1016/j.tibtech.2016.04.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 04/07/2016] [Accepted: 04/11/2016] [Indexed: 11/21/2022]
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162
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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.
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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
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163
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An animal model of Miller Fisher syndrome: Mitochondrial hydrogen peroxide is produced by the autoimmune attack of nerve terminals and activates Schwann cells. Neurobiol Dis 2016; 96:95-104. [PMID: 27597525 DOI: 10.1016/j.nbd.2016.09.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Revised: 08/30/2016] [Accepted: 09/01/2016] [Indexed: 01/08/2023] Open
Abstract
The neuromuscular junction is a tripartite synapse composed of the presynaptic nerve terminal, the muscle and perisynaptic Schwann cells. Its functionality is essential for the execution of body movements and is compromised in a number of disorders, including Miller Fisher syndrome, a variant of Guillain-Barré syndrome: this autoimmune peripheral neuropathy is triggered by autoantibodies specific for the polysialogangliosides GQ1b and GT1a present in motor axon terminals, including those innervating ocular muscles, and in sensory neurons. Their binding to the presynaptic membrane activates the complement cascade, leading to a nerve degeneration that resembles that caused by some animal presynaptic neurotoxins. Here we have studied the intra- and inter-cellular signaling triggered by the binding and complement activation of a mouse monoclonal anti-GQ1b/GT1a antibody to primary cultures of spinal cord motor neurons and cerebellar granular neurons. We found that a membrane attack complex is rapidly assembled following antibody binding, leading to calcium accumulation, which affects mitochondrial functionality. Consequently, using fluorescent probes specific for mitochondrial hydrogen peroxide, we found that this reactive oxygen species is rapidly produced by mitochondria of damaged neurons, and that it triggers the activation of the MAP kinase pathway in Schwann cells. These results throw light on the molecular and cellular pathogenesis of Miller Fisher syndrome, and may well be relevant to other pathologies of the motor axon terminals, including some subtypes of the Guillain Barré syndrome.
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164
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Ramos TN, Arynchyna AA, Blackburn TE, Barnum SR, Johnston JM. Soluble membrane attack complex is diagnostic for intraventricular shunt infection in children. JCI Insight 2016; 1:e87919. [PMID: 27699221 DOI: 10.1172/jci.insight.87919] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Children treated with cerebrospinal fluid (CSF) shunts to manage hydrocephalus frequently develop shunt failure and/or infections, conditions that present with overlapping symptoms. The potential life-threatening nature of shunt infections requires rapid diagnosis; however, traditional microbiology is time consuming, expensive, and potentially unreliable. We set out to identify a biomarker that would identify shunt infection. METHODS CSF was assayed for the soluble membrane attack complex (sMAC) by ELISA in patients with suspected shunt failure or infection. CSF was obtained at the time of initial surgical intervention. Statistical analysis was performed to assess the diagnostic potential of sMAC in pyogenic-infected versus noninfected patients. RESULTS Children with pyogenic shunt infection had significantly increased sMAC levels compared with noninfected patients (3,211 ± 1,111 ng/ml vs. 26 ± 3.8 ng/ml, P = 0.0001). In infected patients undergoing serial CSF draws, sMAC levels were prognostic for both positive and negative clinical outcomes. Children with delayed, broth-only growth of commensal organisms (P. acnes, S. epidermidis, etc.) had the lowest sMAC levels (7.96 ± 1.7 ng/ml), suggesting contamination rather than shunt infection. CONCLUSION Elevated CSF sMAC levels are both sensitive and specific for diagnosing pyogenic shunt infection and may serve as a useful prognostic biomarker during recovery from infection. FUNDING This work was supported in part by the Impact Fund of Children's of Alabama.
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Affiliation(s)
| | - Anastasia A Arynchyna
- Division of Pediatric Neurosurgery, Department of Neurosurgery, Children's of Alabama
| | | | - Scott R Barnum
- Department of Microbiology.,Department of Neurology, University of Alabama at Birmingham (UAB), Birmingham, Alabama, USA
| | - James M Johnston
- Division of Pediatric Neurosurgery, Department of Neurosurgery, Children's of Alabama
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165
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Sharp TH, Koster AJ, Gros P. Heterogeneous MAC Initiator and Pore Structures in a Lipid Bilayer by Phase-Plate Cryo-electron Tomography. Cell Rep 2016; 15:1-8. [PMID: 27052168 DOI: 10.1016/j.celrep.2016.03.002] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 02/09/2016] [Accepted: 02/24/2016] [Indexed: 02/07/2023] Open
Abstract
Pore formation in membranes is important for mammalian immune defense against invading bacteria. Induced by complement activation, the membrane attack complex (MAC) forms through sequential binding and membrane insertion of C5b6, C7, C8, and C9. Using cryo-electron tomography with a Volta phase plate and subtomogram averaging, we imaged C5b-7, C5b-8, and C5b-9 complexes and determined the C5b-9 pore structure in lipid bilayers. The in situ C5b-9 pore structure at 2.3-nm resolution reveals a 10- to 11.5-nm cone-shaped pore starting with C5b678 and multiple copies of C9 that is poorly closed, yielding a seam between C9 and C6 substituting for the shorter β strands in C6 and C7. However, large variations of composite pore complexes are apparent in subtomograms. Oligomerized initiator complexes C5b-7 and C5b-8 show stages of membrane binding, deformation, and perforation that yield ∼3.5-nm-wide pores. These data indicate a dynamic process of pore formation that likely adapts to biological membranes under attack.
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Affiliation(s)
- Thomas H Sharp
- Section Electron Microscopy, Department of Molecular Cell Biology, Leiden University Medical Center, 2300 RC Leiden, the Netherlands.
| | - Abraham J Koster
- Section Electron Microscopy, Department of Molecular Cell Biology, Leiden University Medical Center, 2300 RC Leiden, the Netherlands; NeCEN, Gorlaeus Laboratories, Leiden University, 2333 CC Leiden, the Netherlands
| | - Piet Gros
- Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research and Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands.
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Lukoyanova N, Hoogenboom BW, Saibil HR. The membrane attack complex, perforin and cholesterol-dependent cytolysin superfamily of pore-forming proteins. J Cell Sci 2016; 129:2125-33. [DOI: 10.1242/jcs.182741] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
ABSTRACT
The membrane attack complex and perforin proteins (MACPFs) and bacterial cholesterol-dependent cytolysins (CDCs) are two branches of a large and diverse superfamily of pore-forming proteins that function in immunity and pathogenesis. During pore formation, soluble monomers assemble into large transmembrane pores through conformational transitions that involve extrusion and refolding of two α-helical regions into transmembrane β-hairpins. These transitions entail a dramatic refolding of the protein structure, and the resulting assemblies create large holes in cellular membranes, but they do not use any external source of energy. Structures of the membrane-bound assemblies are required to mechanistically understand and modulate these processes. In this Commentary, we discuss recent advances in the understanding of assembly mechanisms and molecular details of the conformational changes that occur during MACPF and CDC pore formation.
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Affiliation(s)
- Natalya Lukoyanova
- Department of Crystallography/Biological Sciences, Institute of Structural and Molecular Biology, Birkbeck College, London WC1E 7HX, UK
| | - Bart W. Hoogenboom
- London Centre for Nanotechnology, University College London, London WC1H 0AH, UK
- Department of Physics and Astronomy, University College London, London WC1E 6BT, UK
| | - Helen R. Saibil
- Department of Crystallography/Biological Sciences, Institute of Structural and Molecular Biology, Birkbeck College, London WC1E 7HX, UK
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