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Sant'Anna MRV, Pereira-Filho AA, Mendes-Sousa AF, Silva NCS, Gontijo NF, Pereira MH, Koerich LB, D'Avila Pessoa GC, Andersen J, Araujo RN. Inhibition of vertebrate complement system by hematophagous arthropods: inhibitory molecules, mechanisms, physiological roles, and applications. INSECT SCIENCE 2024. [PMID: 38246860 DOI: 10.1111/1744-7917.13317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 10/28/2023] [Accepted: 12/07/2023] [Indexed: 01/23/2024]
Abstract
In arthropods, hematophagy has arisen several times throughout evolution. This specialized feeding behavior offered a highly nutritious diet obtained during blood feeds. On the other hand, blood-sucking arthropods must overcome problems brought on by blood intake and digestion. Host blood complement acts on the bite site and is still active after ingestion, so complement activation is a potential threat to the host's skin feeding environment and to the arthropod gut enterocytes. During evolution, blood-sucking arthropods have selected, either in their saliva or gut, anticomplement molecules that inactivate host blood complement. This review presents an overview of the complement system and discusses the arthropod's salivary and gut anticomplement molecules studied to date, exploring their mechanism of action and other aspects related to the arthropod-host-pathogen interface. The possible therapeutic applications of arthropod's anticomplement molecules are also discussed.
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Affiliation(s)
- Mauricio Roberto Vianna Sant'Anna
- Department of Parasitology, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
- Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular, Rio de Janeiro, RJ, Brazil
| | - Adalberto Alves Pereira-Filho
- Department of Parasitology, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | | | - Naylene Carvalho Sales Silva
- Department of Parasitology, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Nelder Figueiredo Gontijo
- Department of Parasitology, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
- Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular, Rio de Janeiro, RJ, Brazil
| | - Marcos Horácio Pereira
- Department of Parasitology, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
- Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular, Rio de Janeiro, RJ, Brazil
| | - Leonardo Barbosa Koerich
- Department of Parasitology, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
- Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular, Rio de Janeiro, RJ, Brazil
| | - Grasielle Caldas D'Avila Pessoa
- Department of Parasitology, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
- Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular, Rio de Janeiro, RJ, Brazil
| | - John Andersen
- Vector Molecular Biology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, USA
| | - Ricardo Nascimento Araujo
- Department of Parasitology, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
- Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular, Rio de Janeiro, RJ, Brazil
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2
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C AM, Wessler S, Ponnuraj K. Inhibition of Listeria Monocytogenes HtrA Protease with Camostat, Gabexate and Nafamostat Mesylates and the Binding Mode of the Inhibitors. Protein J 2023:10.1007/s10930-023-10114-8. [PMID: 37093417 PMCID: PMC10123570 DOI: 10.1007/s10930-023-10114-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/12/2023] [Indexed: 04/25/2023]
Abstract
In many bacteria, the High Temperature requirement A (HtrA) protein functions as a chaperone and protease. HtrA is an important factor in stress tolerance and plays a significant role in the virulence of several pathogenic bacteria. Camostat, gabexate and nafamostat mesylates are serine protease inhibitors and have recently shown a great impact in the inhibition studies of SARS-CoV2. In this study, the inhibition of Listeria monocytogenes HtrA (LmHtrA) protease activity was analysed using these three inhibitors. The cleavage assay, using human fibrinogen and casein as substrates, revealed that the three inhibitors effectively inhibit the protease activity of LmHtrA. The agar plate assay and spectrophotometric analysis concluded that the inhibition of nafamostat (IC50 value of 6.6 ± 0.4 µM) is more effective compared to the other two inhibitors. Previous studies revealed that at the active site of the protease, these inhibitors are hydrolysed and one of the hydrolysates is covalently bound to the active site serine. To understand the mode of binding of these inhibitors at the active site of LmHtrA, docking of the inhibitors followed by molecular dynamics simulations were carried out. Analysis of the LmHtrA-inhibitor complex structures revealed that the covalently bound inhibitor is unable to occupy the S1 pocket of the LmHtrA which is in contrast to the previously determined camostat and nafamostat complex structures. This observation provides the first glimpse of the substrate specificity of LmHtrA which is not known. The obtained results also suggest that the development of novel inhibitors of LmHtrA and its homologs with active site architecture similar to LmHtrA can be pursued with suitable modification of these inhibitors. To date, only a very few studies have been carried out on identifying the inhibitors of HtrA proteolytic activity.
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Affiliation(s)
- Amrutha M C
- Centre of Advanced Study in Crystallography and Biophysics, University of Madras, Guindy Campus, Chennai, 600 025, India
| | - Silja Wessler
- Department of Biosciences and Medical Biology, University of Salzburg, Hellbrunner Str. 34, Salzburg, A-5020, Austria
| | - Karthe Ponnuraj
- Centre of Advanced Study in Crystallography and Biophysics, University of Madras, Guindy Campus, Chennai, 600 025, India.
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Schubart A, Flohr S, Junt T, Eder J. Low-molecular weight inhibitors of the alternative complement pathway. Immunol Rev 2023; 313:339-357. [PMID: 36217774 PMCID: PMC10092480 DOI: 10.1111/imr.13143] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Dysregulation of the alternative complement pathway predisposes individuals to a number of diseases. It can either be evoked by genetic alterations in or by stabilizing antibodies to important pathway components and typically leads to severe diseases such as paroxysmal nocturnal hemoglobinuria, atypical hemolytic uremic syndrome, C3 glomerulopathy, and age-related macular degeneration. In addition, the alternative pathway may also be involved in many other diseases where its amplifying function for all complement pathways might play a role. To identify specific alternative pathway inhibitors that qualify as therapeutics for these diseases, drug discovery efforts have focused on the two central proteases of the pathway, factor B and factor D. Although drug discovery has been challenging for a number of reasons, potent and selective low-molecular weight (LMW) oral inhibitors have now been discovered for both proteases and several molecules are in clinical development for multiple complement-mediated diseases. While the clinical development of these inhibitors initially focuses on diseases with systemic and/or peripheral tissue complement activation, the availability of LMW inhibitors may also open up the prospect of inhibiting complement in the central nervous system where its activation may also play an important role in several neurodegenerative diseases.
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Affiliation(s)
- Anna Schubart
- Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Stefanie Flohr
- Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Tobias Junt
- Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Jörg Eder
- Novartis Institutes for BioMedical Research, Basel, Switzerland
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Gavriilaki E, Papakonstantinou A, Agrios KA. Novel Insights into Factor D Inhibition. Int J Mol Sci 2022; 23:ijms23137216. [PMID: 35806224 PMCID: PMC9267021 DOI: 10.3390/ijms23137216] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 06/23/2022] [Accepted: 06/23/2022] [Indexed: 01/15/2023] Open
Abstract
Complement-mediated diseases or complementopathies, such as Paroxysmal nocturnal hemoglobinuria (PNH), cold agglutinin disease (CAD), and transplant-associated thrombotic microangiopathy (TA-TMA), demand advanced complement diagnostics and therapeutics be adopted in a vast field of medical specialties, such as hematology, transplantation, rheumatology, and nephrology. The miracle of complement inhibitors as “orphan drugs” has dramatically improved morbidity and mortality in patients with otherwise life-threatening complementopathies. Efficacy has been significantly improved by upstream inhibition in patients with PNH. Different molecules may exert diverse characteristics in vitro and in vivo. Further studies remain to show safety and efficacy of upstream inhibition in other complementopathies. In addition, cost and availability issues are major drawbacks of current treatments. Therefore, further developments are warranted to address the unmet clinical needs in the field of complementopathies. This state-of-the-art narrative review aims to delineate novel insights into factor D inhibition as a promising target for complementopathies.
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Affiliation(s)
- Eleni Gavriilaki
- Hematology Department, G Papanicolaou Hospital, 57010 Thessaloniki, Greece
- Correspondence: (E.G.); (K.A.A.)
| | - Anna Papakonstantinou
- Department of Urology, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece;
| | - Konstantinos A. Agrios
- Department of Chemistry, Villanova University, 800 Lancaster Ave., Villanova, PA 19085, USA
- Correspondence: (E.G.); (K.A.A.)
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Sultan EY, Rizk DE, Kenawy HI, Hassan R. A small fragment of factor B as a potential inhibitor of complement alternative pathway activity. Immunobiology 2021; 226:152106. [PMID: 34147816 DOI: 10.1016/j.imbio.2021.152106] [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: 03/11/2021] [Revised: 06/06/2021] [Accepted: 06/08/2021] [Indexed: 10/21/2022]
Abstract
BACKGROUND The complement system is a key player in innate immunity and a modulator of the adaptive immune system. Among the three pathways of complement, the alternative pathway (AP) accounts for most of the complement activation. Factor B (FB) is a major protease of the AP, making it a promising target to inhibit the AP activity in conditions of uncontrolled complement activation. METHODS Based on the data obtained from sequence analysis and conformational changes associated with FB, we expressed and purified a recombinant FB fragment (FBfr). We tested the inhibitory activity of the protein against the AP by in vitro assays. RESULTS FBfr protein was proven to inhibit the complement AP activity when tested by C3b deposition assay and rabbit erythrocyte hemolytic assay. CONCLUSION Our recombinant FBfr was able to compete with the native human FB, which allowed it to inhibit the AP activity. This novel compound is a good candidate for further characterization and testing to be used in complement diagnostic tests and as a drug lead in the field of complement therapeutics.
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Affiliation(s)
- Enas Yasser Sultan
- Department of Microbiology & Immunology, Faculty of Pharmacy, Mansoura University, Egypt
| | - Dina Eid Rizk
- Department of Microbiology & Immunology, Faculty of Pharmacy, Mansoura University, Egypt
| | - Hany Ibrahim Kenawy
- Department of Microbiology & Immunology, Faculty of Pharmacy, Mansoura University, Egypt.
| | - Ramadan Hassan
- Department of Microbiology & Immunology, Faculty of Pharmacy, Mansoura University, Egypt
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6
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Gauthier A, Wagner E, Thibeault R, Lavoie A. A Novel Case of Complement Factor B Deficiency. J Clin Immunol 2020; 41:277-279. [PMID: 33165708 DOI: 10.1007/s10875-020-00906-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Accepted: 10/30/2020] [Indexed: 01/16/2023]
Affiliation(s)
- Amélie Gauthier
- Department of Allergy and Immunology, CHU de Québec-CHUL, Laval University Hospital Center, Laval University, Quebec City, G1V 4G2, Canada.
| | - Eric Wagner
- Immunology and Histocompatibility Laboratory, CHU de Québec-Université Laval and Department of Microbiology-Infectiology and Immunology, Laval University, Quebec City, QC, G1V 4G2, Canada
| | - Roseline Thibeault
- Department of Pediatrics, CHU de Québec-CHUL, Laval University, Quebec City, G1V 4G2, Canada
| | - Aubert Lavoie
- Department of Allergy and Immunology, CHU de Québec-CHUL, Laval University Hospital Center, Laval University, Quebec City, G1V 4G2, Canada
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Solmaz I, Kocak E, Kaplan O, Celebier M, Anlar B. Analysis of plasma protein biomarkers in childhood onset multiple sclerosis. J Neuroimmunol 2020; 348:577359. [DOI: 10.1016/j.jneuroim.2020.577359] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2020] [Revised: 07/24/2020] [Accepted: 08/06/2020] [Indexed: 12/19/2022]
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Gyulkhandanyan A, Rezaie AR, Roumenina L, Lagarde N, Fremeaux-Bacchi V, Miteva MA, Villoutreix BO. Analysis of protein missense alterations by combining sequence- and structure-based methods. Mol Genet Genomic Med 2020; 8:e1166. [PMID: 32096919 PMCID: PMC7196459 DOI: 10.1002/mgg3.1166] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 01/20/2020] [Accepted: 01/27/2020] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Different types of in silico approaches can be used to predict the phenotypic consequence of missense variants. Such algorithms are often categorized as sequence based or structure based, when they necessitate 3D structural information. In addition, many other in silico tools, not dedicated to the analysis of variants, can be used to gain additional insights about the possible mechanisms at play. METHODS Here we applied different computational approaches to a set of 20 known missense variants present on different proteins (CYP, complement factor B, antithrombin and blood coagulation factor VIII). The tools that were used include fast computational approaches and web servers such as PolyPhen-2, PopMusic, DUET, MaestroWeb, SAAFEC, Missense3D, VarSite, FlexPred, PredyFlexy, Clustal Omega, meta-PPISP, FTMap, ClusPro, pyDock, PPM, RING, Cytoscape, and ChannelsDB. RESULTS We observe some conflicting results among the methods but, most of the time, the combination of several engines helped to clarify the potential impacts of the amino acid substitutions. CONCLUSION Combining different computational approaches including some that were not developed to investigate missense variants help to predict the possible impact of the amino acid substitutions. Yet, when the modified residues are involved in a salt-bridge, the tools tend to fail, even when the analysis is performed in 3D. Thus, interactive structural analysis with molecular graphics packages such as Chimera or PyMol or others are still needed to clarify automatic prediction.
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Affiliation(s)
- Aram Gyulkhandanyan
- INSERM U973, Laboratory MTi, University Paris Diderot, Paris, France
- Laboratory SABNP, University of Evry, INSERM U1204, Université Paris-Saclay, Evry, France
| | - Alireza R Rezaie
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Lubka Roumenina
- INSERM, UMR_S 1138, Centre de Recherche des Cordeliers, Paris, France
- Sorbonne Universités, Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Nathalie Lagarde
- INSERM U973, Laboratory MTi, University Paris Diderot, Paris, France
- Laboratoire GBCM, EA7528, Conservatoire national des arts et métiers, Hesam Université, Paris, France
| | - Veronique Fremeaux-Bacchi
- INSERM, UMR_S 1138, Centre de Recherche des Cordeliers, Paris, France
- Sorbonne Universités, Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, Paris, France
- Assistance Publique-Hôpitaux de Paris, Service d'Immunologie Biologique, Hôpital Européen Georges Pompidou, Paris, France
| | - Maria A Miteva
- INSERM U973, Laboratory MTi, University Paris Diderot, Paris, France
- Inserm U1268 MCTR, CNRS UMR 8038 CiTCoM, Faculté de Pharmacie de Paris, Univ. De Paris, Paris, France
| | - Bruno O Villoutreix
- INSERM U973, Laboratory MTi, University Paris Diderot, Paris, France
- INSERM, Institut Pasteur de Lille, U1177-Drugs and Molecules for Living Systems, Université de Lille, Lille, France
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9
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Denesyuk AI, Johnson MS, Salo-Ahen OMH, Uversky VN, Denessiouk K. NBCZone: Universal three-dimensional construction of eleven amino acids near the catalytic nucleophile and base in the superfamily of (chymo)trypsin-like serine fold proteases. Int J Biol Macromol 2020; 153:399-411. [PMID: 32151723 PMCID: PMC7124590 DOI: 10.1016/j.ijbiomac.2020.03.025] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 03/02/2020] [Accepted: 03/03/2020] [Indexed: 10/25/2022]
Abstract
(Chymo)trypsin-like serine fold proteases belong to the serine/cysteine proteases found in eukaryotes, prokaryotes, and viruses. Their catalytic activity is carried out using a triad of amino acids, a nucleophile, a base, and an acid. For this superfamily of proteases, we propose the existence of a universal 3D structure comprising 11 amino acids near the catalytic nucleophile and base - Nucleophile-Base Catalytic Zone (NBCZone). The comparison of NBCZones among 169 eukaryotic, prokaryotic, and viral (chymo)trypsin-like proteases suggested the existence of 15 distinct groups determined by the combination of amino acids located at two "key" structure-functional positions 54T and 55T near the catalytic base His57T. Most eukaryotic and prokaryotic proteases fell into two major groups, [ST]A and TN. Usually, proteases of [ST]A group contain a disulfide bond between cysteines Cys42T and Cys58T of the NBCZone. In contrast, viral proteases were distributed among seven groups, and lack this disulfide bond. Furthermore, only the [ST]A group of eukaryotic proteases contains glycine at position 43T, which is instrumental for activation of these enzymes. In contrast, due to the side chains of residues at position 43T prokaryotic and viral proteases do not have the ability to carry out the structural transition of the eukaryotic zymogen-zyme type.
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Affiliation(s)
- Alexander I Denesyuk
- Institute for Biological Instrumentation of the Russian Academy of Sciences, Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", 142290 Pushchino, Russia; Structural Bioinformatics Laboratory, Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, 20520 Turku, Finland.
| | - Mark S Johnson
- Structural Bioinformatics Laboratory, Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, 20520 Turku, Finland
| | - Outi M H Salo-Ahen
- Structural Bioinformatics Laboratory, Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, 20520 Turku, Finland; Pharmaceutical Sciences Laboratory, Pharmacy, Faculty of Science and Engineering, Åbo Akademi University, 20520 Turku, Finland
| | - Vladimir N Uversky
- Institute for Biological Instrumentation of the Russian Academy of Sciences, Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", 142290 Pushchino, Russia; Department of Molecular Medicine and USF Health Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA.
| | - Konstantin Denessiouk
- Structural Bioinformatics Laboratory, Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, 20520 Turku, Finland; Pharmaceutical Sciences Laboratory, Pharmacy, Faculty of Science and Engineering, Åbo Akademi University, 20520 Turku, Finland
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10
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Mainolfi N, Ehara T, Karki RG, Anderson K, Mac Sweeney A, Liao SM, Argikar UA, Jendza K, Zhang C, Powers J, Klosowski DW, Crowley M, Kawanami T, Ding J, April M, Forster C, Serrano-Wu M, Capparelli M, Ramqaj R, Solovay C, Cumin F, Smith TM, Ferrara L, Lee W, Long D, Prentiss M, De Erkenez A, Yang L, Liu F, Sellner H, Sirockin F, Valeur E, Erbel P, Ostermeier D, Ramage P, Gerhartz B, Schubart A, Flohr S, Gradoux N, Feifel R, Vogg B, Wiesmann C, Maibaum J, Eder J, Sedrani R, Harrison RA, Mogi M, Jaffee BD, Adams CM. Discovery of 4-((2 S,4 S)-4-Ethoxy-1-((5-methoxy-7-methyl-1 H-indol-4-yl)methyl)piperidin-2-yl)benzoic Acid (LNP023), a Factor B Inhibitor Specifically Designed To Be Applicable to Treating a Diverse Array of Complement Mediated Diseases. J Med Chem 2020; 63:5697-5722. [PMID: 32073845 DOI: 10.1021/acs.jmedchem.9b01870] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The alternative pathway (AP) of the complement system is a key contributor to the pathogenesis of several human diseases including age-related macular degeneration, paroxysmal nocturnal hemoglobinuria (PNH), atypical hemolytic uremic syndrome (aHUS), and various glomerular diseases. The serine protease factor B (FB) is a key node in the AP and is integral to the formation of C3 and C5 convertase. Despite the prominent role of FB in the AP, selective orally bioavailable inhibitors, beyond our own efforts, have not been reported previously. Herein we describe in more detail our efforts to identify FB inhibitors by high-throughput screening (HTS) and leveraging insights from several X-ray cocrystal structures during optimization efforts. This work culminated in the discovery of LNP023 (41), which is currently being evaluated clinically in several diverse AP mediated indications.
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Affiliation(s)
- Nello Mainolfi
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - Takeru Ehara
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - Rajeshri G Karki
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - Karen Anderson
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - Aengus Mac Sweeney
- Novartis Institutes for BioMedical Research, Novartis Pharma AG, CH-4056 Basel, Switzerland
| | - Sha-Mei Liao
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - Upendra A Argikar
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - Keith Jendza
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - Chun Zhang
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - James Powers
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - Daniel W Klosowski
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - Maura Crowley
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - Toshio Kawanami
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - Jian Ding
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - Myriam April
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - Cornelia Forster
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - Michael Serrano-Wu
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - Michael Capparelli
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - Rrezarta Ramqaj
- Novartis Institutes for BioMedical Research, Novartis Pharma AG, CH-4056 Basel, Switzerland
| | - Catherine Solovay
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - Frederic Cumin
- Novartis Institutes for BioMedical Research, Novartis Pharma AG, CH-4056 Basel, Switzerland
| | - Thomas M Smith
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - Luciana Ferrara
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - Wendy Lee
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - Debby Long
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - Melissa Prentiss
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - Andrea De Erkenez
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - Louis Yang
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - Fang Liu
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - Holger Sellner
- Novartis Institutes for BioMedical Research, Novartis Pharma AG, CH-4056 Basel, Switzerland
| | - Finton Sirockin
- Novartis Institutes for BioMedical Research, Novartis Pharma AG, CH-4056 Basel, Switzerland
| | - Eric Valeur
- Novartis Institutes for BioMedical Research, Novartis Pharma AG, CH-4056 Basel, Switzerland
| | - Paulus Erbel
- Novartis Institutes for BioMedical Research, Novartis Pharma AG, CH-4056 Basel, Switzerland
| | - Daniela Ostermeier
- Novartis Institutes for BioMedical Research, Novartis Pharma AG, CH-4056 Basel, Switzerland
| | - Paul Ramage
- Novartis Institutes for BioMedical Research, Novartis Pharma AG, CH-4056 Basel, Switzerland
| | - Bernd Gerhartz
- Novartis Institutes for BioMedical Research, Novartis Pharma AG, CH-4056 Basel, Switzerland
| | - Anna Schubart
- Novartis Institutes for BioMedical Research, Novartis Pharma AG, CH-4056 Basel, Switzerland
| | - Stefanie Flohr
- Novartis Institutes for BioMedical Research, Novartis Pharma AG, CH-4056 Basel, Switzerland
| | - Nathalie Gradoux
- Novartis Institutes for BioMedical Research, Novartis Pharma AG, CH-4056 Basel, Switzerland
| | - Roland Feifel
- Novartis Institutes for BioMedical Research, Novartis Pharma AG, CH-4056 Basel, Switzerland
| | - Barbara Vogg
- Novartis Institutes for BioMedical Research, Novartis Pharma AG, CH-4056 Basel, Switzerland
| | - Christian Wiesmann
- Novartis Institutes for BioMedical Research, Novartis Pharma AG, CH-4056 Basel, Switzerland
| | - Jürgen Maibaum
- Novartis Institutes for BioMedical Research, Novartis Pharma AG, CH-4056 Basel, Switzerland
| | - Jörg Eder
- Novartis Institutes for BioMedical Research, Novartis Pharma AG, CH-4056 Basel, Switzerland
| | - Richard Sedrani
- Novartis Institutes for BioMedical Research, Novartis Pharma AG, CH-4056 Basel, Switzerland
| | - Richard A Harrison
- Novartis Institutes for BioMedical Research, Novartis Pharma AG, CH-4056 Basel, Switzerland
| | - Muneto Mogi
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - Bruce D Jaffee
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
| | - Christopher M Adams
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, United States
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Role of the I16-D194 ionic interaction in the trypsin fold. Sci Rep 2019; 9:18035. [PMID: 31792294 PMCID: PMC6889508 DOI: 10.1038/s41598-019-54564-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Accepted: 11/15/2019] [Indexed: 12/20/2022] Open
Abstract
Activity in trypsin-like proteases is the result of proteolytic cleavage at R15 followed by an ionic interaction that ensues between the new N terminus of I16 and the side chain of the highly conserved D194. This mechanism of activation, first proposed by Huber and Bode, organizes the oxyanion hole and primary specificity pocket for substrate binding and catalysis. Using the clotting protease thrombin as a relevant model, we unravel contributions of the I16-D194 ionic interaction to Na+ binding, stability of the transition state and the allosteric E*-E equilibrium of the trypsin fold. The I16T mutation abolishes the I16-D194 interaction and compromises the architecture of the oxyanion hole. The D194A mutation also abrogates the I16-D194 interaction but, surprisingly, has no effect on the architecture of the oxyanion hole that remains intact through a new H-bond established between G43 and G193. In both mutants, loss of the I16-D194 ionic interaction compromises Na+ binding, reduces stability of the transition state, collapses the 215–217 segment into the primary specific pocket and abrogates the allosteric E*-E equilibrium in favor of a rigid conformation that binds ligand at the active site according to a simple lock-and-key mechanism. These findings refine the structural role of the I16-D194 ionic interaction in the Huber-Bode mechanism of activation and reveal a functional linkage with the allosteric properties of the trypsin fold like Na+ binding and the E*-E equilibrium.
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12
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Abstract
Complement is a key component of the innate immune system; however, its dysregulation due to genetic mutations or the presence of autoantibodies can cause a number of diseases including age-related macular degeneration, paroxysmal nocturnal hemoglobinuria, and C3 glomerulopathy. The alternative pathway acts as an amplification loop of the complement system. It is triggered by the activation of factor B, the proteolytically active component of the C3 and C5 convertases. We report the discovery of a small-molecule inhibitor of factor B and demonstrate that it can efficiently block the alternative pathway in vivo in animals and ex vivo in patient samples. The compound is highly selective and potent and is currently in clinical development for a number of complement-mediated diseases. Dysregulation of the alternative complement pathway (AP) predisposes individuals to a number of diseases including paroxysmal nocturnal hemoglobinuria, atypical hemolytic uremic syndrome, and C3 glomerulopathy. Moreover, glomerular Ig deposits can lead to complement-driven nephropathies. Here we describe the discovery of a highly potent, reversible, and selective small-molecule inhibitor of factor B, a serine protease that drives the central amplification loop of the AP. Oral administration of the inhibitor prevents KRN-induced arthritis in mice and is effective upon prophylactic and therapeutic dosing in an experimental model of membranous nephropathy in rats. In addition, inhibition of factor B prevents complement activation in sera from C3 glomerulopathy patients and the hemolysis of human PNH erythrocytes. These data demonstrate the potential therapeutic value of using a factor B inhibitor for systemic treatment of complement-mediated diseases and provide a basis for its clinical development.
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13
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Estelius J, Lengqvist J, Ossipova E, Idborg H, Le Maître E, Andersson MLA, Brundin L, Khademi M, Svenungsson E, Jakobsson PJ, Lampa J. Mass spectrometry-based analysis of cerebrospinal fluid from arthritis patients-immune-related candidate proteins affected by TNF blocking treatment. Arthritis Res Ther 2019; 21:60. [PMID: 30770760 PMCID: PMC6377734 DOI: 10.1186/s13075-019-1846-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 02/06/2019] [Indexed: 12/16/2022] Open
Abstract
Background Signs of inflammation in cerebrospinal fluid (CSF) of rheumatoid arthritis patients correlate positively with fatigue, a central nervous system (CNS)-related symptom that can be partially suppressed by TNF blockade. This suggests a possible role for CNS inflammation in arthritis that may be affected by TNF blockade. We therefore investigated the effects of TNF blockade on the arthritis CSF proteome and how candidate proteins related to clinical measures of disease activity and inflammation. Methods Mass spectrometry-based quantitative proteomic analysis was performed on CSF from seven polyarthritis patients before and during infliximab treatment. Treatment-associated proteins were identified using univariate (Wilcoxon signed rank test) and multivariate (partial least squares discriminant analysis (PLS-DA)) strategies. Relations between selected candidate proteins and clinical measures were investigated using the Spearman correlations. Additionally, selected proteins were cross-referenced to other studies investigating human CSF in a thorough literature search to ensure feasibility of our results. Results Univariate analysis of arthritis CSF proteome revealed a decrease of 35 proteins, predominantly involved in inflammatory processes, following TNF blockade. Seven candidate proteins, Contactin-1 (CNTN1), fibrinogen gamma chain (FGG), hemopexin (HPX), cell adhesion molecule-3 (CADM3), alpha-1B-glycoprotein (A1BG), complement factor B (CFB), and beta-2-microglobulin (B2M), were selected for further studies based on identification by both univariate and multivariate analyses and reported detection in human CSF and known associations to arthritis. Decreased levels of FGG and CFB in CSF after treatment showed strong correlations with both erythrocyte sedimentation rate and disability scores, while CNTN1 and CADM3 were associated with pain. Conclusion Several immune-related proteins in the CSF of arthritis patients decreased during TNF blockade, including FGG and CFB that both correlated strongly with systemic inflammation. Our findings stress that also intrathecal inflammatory pathways are related to arthritis symptoms and may be affected by TNF blockade. Electronic supplementary material The online version of this article (10.1186/s13075-019-1846-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Johanna Estelius
- Rheumatology Unit, Department of Medicine, Solna, Center of Molecular Medicine (CMM), Karolinska Institutet, Karolinska University Hospital, SE-17176, Stockholm, Sweden
| | - Johan Lengqvist
- Rheumatology Unit, Department of Medicine, Solna, Center of Molecular Medicine (CMM), Karolinska Institutet, Karolinska University Hospital, SE-17176, Stockholm, Sweden
| | - Elena Ossipova
- Rheumatology Unit, Department of Medicine, Solna, Center of Molecular Medicine (CMM), Karolinska Institutet, Karolinska University Hospital, SE-17176, Stockholm, Sweden
| | - Helena Idborg
- Rheumatology Unit, Department of Medicine, Solna, Center of Molecular Medicine (CMM), Karolinska Institutet, Karolinska University Hospital, SE-17176, Stockholm, Sweden
| | - Erwan Le Maître
- Rheumatology Unit, Department of Medicine, Solna, Center of Molecular Medicine (CMM), Karolinska Institutet, Karolinska University Hospital, SE-17176, Stockholm, Sweden
| | - Magnus L A Andersson
- Neuroimmunology Unit, Department of Clinical Neuroscience, Center of Molecular Medicine (CMM), Karolinska Institutet, Karolinska University Hospital, SE-17176, Stockholm, Sweden
| | - Lou Brundin
- Neuroimmunology Unit, Department of Clinical Neuroscience, Center of Molecular Medicine (CMM), Karolinska Institutet, Karolinska University Hospital, SE-17176, Stockholm, Sweden
| | - Mohsen Khademi
- Neuroimmunology Unit, Department of Clinical Neuroscience, Center of Molecular Medicine (CMM), Karolinska Institutet, Karolinska University Hospital, SE-17176, Stockholm, Sweden
| | - Elisabet Svenungsson
- Rheumatology Unit, Department of Medicine, Solna, Center of Molecular Medicine (CMM), Karolinska Institutet, Karolinska University Hospital, SE-17176, Stockholm, Sweden
| | - Per-Johan Jakobsson
- Rheumatology Unit, Department of Medicine, Solna, Center of Molecular Medicine (CMM), Karolinska Institutet, Karolinska University Hospital, SE-17176, Stockholm, Sweden
| | - Jon Lampa
- Rheumatology Unit, Department of Medicine, Solna, Center of Molecular Medicine (CMM), Karolinska Institutet, Karolinska University Hospital, SE-17176, Stockholm, Sweden.
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14
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Kenny LC, Kell DB. Immunological Tolerance, Pregnancy, and Preeclampsia: The Roles of Semen Microbes and the Father. Front Med (Lausanne) 2018; 4:239. [PMID: 29354635 PMCID: PMC5758600 DOI: 10.3389/fmed.2017.00239] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Accepted: 12/12/2017] [Indexed: 12/18/2022] Open
Abstract
Although it is widely considered, in many cases, to involve two separable stages (poor placentation followed by oxidative stress/inflammation), the precise originating causes of preeclampsia (PE) remain elusive. We have previously brought together some of the considerable evidence that a (dormant) microbial component is commonly a significant part of its etiology. However, apart from recognizing, consistent with this view, that the many inflammatory markers of PE are also increased in infection, we had little to say about immunity, whether innate or adaptive. In addition, we focused on the gut, oral and female urinary tract microbiomes as the main sources of the infection. We here marshall further evidence for an infectious component in PE, focusing on the immunological tolerance characteristic of pregnancy, and the well-established fact that increased exposure to the father's semen assists this immunological tolerance. As well as these benefits, however, semen is not sterile, microbial tolerance mechanisms may exist, and we also review the evidence that semen may be responsible for inoculating the developing conceptus (and maybe the placenta) with microbes, not all of which are benign. It is suggested that when they are not, this may be a significant cause of PE. A variety of epidemiological and other evidence is entirely consistent with this, not least correlations between semen infection, infertility and PE. Our view also leads to a series of other, testable predictions. Overall, we argue for a significant paternal role in the development of PE through microbial infection of the mother via insemination.
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Affiliation(s)
- Louise C. Kenny
- The Irish Centre for Fetal and Neonatal Translational Research (INFANT), University College Cork, Cork, Ireland
- Department of Obstetrics and Gynecology, University College Cork, Cork, Ireland
- Faculty of Health and Life Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Douglas B. Kell
- School of Chemistry, The University of Manchester, Manchester, United Kingdom
- The Manchester Institute of Biotechnology, The University of Manchester, Manchester, United Kingdom
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15
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Yang CS, Wei YS, Tsai HL, Cheong IS, Chang SJ, Chou HC, Lee YR, Chan HL. Proteomic analysis of prognostic plasma biomarkers in peripheral arterial occlusive disease. MOLECULAR BIOSYSTEMS 2017; 13:1297-1303. [DOI: 10.1039/c7mb00229g] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
A comprehensive patient-based plasma proteomic approach for the identification of potential plasma biomarkers for the screening and detection of good/poor prognosis of peripheral arterial occlusive disease (PAOD).
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Affiliation(s)
- Cheng-San Yang
- Division of Plastic Surgery
- Department of Surgery
- Ditmanson Medical Foundation Chia-Yi Christian Hospital
- Chiayi
- Taiwan
| | - Yu-Shan Wei
- Institute of Bioinformatics and Structural Biology and Department of Medical Science
- National Tsing Hua University
- Hsinchu
- Taiwan
| | - Han-Lin Tsai
- Division of Cardiology
- Department of Internal Medicine
- Ditmanson Medical Foundation Chia-Yi Christian Hospital
- Chiayi
- Taiwan
| | - Ian-Seng Cheong
- Divisions of Urology
- Department of Surgery
- Ditmanson Medical Foundation Chia-Yi Christian Hospital
- Chiayi
- Taiwan
| | - Shing-Jyh Chang
- Gynecologic Oncology Section
- Department of Obstetrics and Gynecology
- Hsinchu Mackay Memorial Hospital
- Hsinchu
- Taiwan
| | - Hsiu-Chuan Chou
- Department of Biomedical Engineering and Environmental Sciences
- National Tsing Hua University
- Hsinchu
- Taiwan
| | - Ying-Ray Lee
- Department of Medical Research
- Ditmanson Medical Foundation Chia-Yi Christian Hospital
- Chiayi
- Taiwan
| | - Hong-Lin Chan
- Institute of Bioinformatics and Structural Biology and Department of Medical Science
- National Tsing Hua University
- Hsinchu
- Taiwan
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16
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Ricklin D, Reis ES, Mastellos DC, Gros P, Lambris JD. Complement component C3 - The "Swiss Army Knife" of innate immunity and host defense. Immunol Rev 2016; 274:33-58. [PMID: 27782325 PMCID: PMC5427221 DOI: 10.1111/imr.12500] [Citation(s) in RCA: 265] [Impact Index Per Article: 33.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
As a preformed defense system, complement faces a delicate challenge in providing an immediate, forceful response to pathogens even at first encounter, while sparing host cells in the process. For this purpose, it engages a tightly regulated network of plasma proteins, cell surface receptors, and regulators. Complement component C3 plays a particularly versatile role in this process by keeping the cascade alert, acting as a point of convergence of activation pathways, fueling the amplification of the complement response, exerting direct effector functions, and helping to coordinate downstream immune responses. In recent years, it has become evident that nature engages the power of C3 not only to clear pathogens but also for a variety of homeostatic processes ranging from tissue regeneration and synapse pruning to clearing debris and controlling tumor cell progression. At the same time, its central position in immune surveillance makes C3 a target for microbial immune evasion and, if improperly engaged, a trigger point for various clinical conditions. In our review, we look at the versatile roles and evolutionary journey of C3, discuss new insights into the molecular basis for C3 function, provide examples of disease involvement, and summarize the emerging potential of C3 as a therapeutic target.
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Affiliation(s)
- Daniel Ricklin
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA.
| | - Edimara S Reis
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Dimitrios C Mastellos
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA
- National Center for Scientific Research 'Demokritos', Athens, Greece
| | - Piet Gros
- Utrecht University, Utrecht, The Netherlands
| | - John D Lambris
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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17
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Abstract
Integrins comprise a large family of αβ heterodimeric cell adhesion receptors that are expressed on all cells except red blood cells and that play essential roles in the regulation of cell growth and function. The leukocyte integrins, which include members of the β
1, β
2, β
3, and β
7 integrin family, are critical for innate and adaptive immune responses but also can contribute to many inflammatory and autoimmune diseases when dysregulated. This review focuses on the β
2 integrins, the principal integrins expressed on leukocytes. We review their discovery and role in host defense, the structural basis for their ligand recognition and activation, and their potential as therapeutic targets.
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Affiliation(s)
- M Amin Arnaout
- Leukocyte Biology & Inflammation Program, Structural Biology Program, Nephrology, Center for Regenerative Medicine, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
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18
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Jusko M, Miedziak B, Ermert D, Magda M, King BC, Bielecka E, Riesbeck K, Eick S, Potempa J, Blom AM. FACIN, a Double-Edged Sword of the Emerging Periodontal Pathogen Filifactor alocis: A Metabolic Enzyme Moonlighting as a Complement Inhibitor. THE JOURNAL OF IMMUNOLOGY 2016; 197:3245-3259. [PMID: 27638863 DOI: 10.4049/jimmunol.1600739] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 08/20/2016] [Indexed: 02/01/2023]
Abstract
Periodontal disease is one of the most common inflammatory infectious diseases worldwide and it is associated with other syndromes, such as cardiovascular disease or rheumatoid arthritis. Recent advances in sequencing allowed for identification of novel periodontopathogens such as Gram-positive Filifactor alocis, but its virulence mechanisms remain largely unknown. We confirmed that F. alocis is a prevalent species in periodontitis patients, and we also observed strong correlation of this bacterium with clinical parameters, highlighting its role in the pathogenesis of the disease. Further, we found that preincubation of human serum with F. alocis resulted in abolished bactericidal activity and that F. alocis was surviving readily in full blood. We demonstrated that one of the key contributors to F. alocis complement resistance is a unique protein, FACIN (F. alocis complement inhibitor), which binds to C3, resulting in suppression of all complement pathways. Interestingly, FACIN is a nonclassical cell surface protein, a cytosolic enzyme acetylornithine transaminase, for which we now identified a moonlighting function. FACIN binds to C3 alone, but more importantly it also captures activated complement factor 3 within the complex with factor B, thereby locking in the convertase in an inactive state. Because of the indispensable role of alternative pathway convertase in amplifying complement cascades, its inhibition by FACIN results in a very potent downregulation of activated complement factor 3 opsonization on the pathogen surface, accompanied by reduction of downstream C5 cleavage.
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Affiliation(s)
- Monika Jusko
- Section of Protein Chemistry, Department of Translational Medicine, Lund University, 205 02 Malmö, Sweden
| | - Beata Miedziak
- Section of Protein Chemistry, Department of Translational Medicine, Lund University, 205 02 Malmö, Sweden
| | - David Ermert
- Section of Protein Chemistry, Department of Translational Medicine, Lund University, 205 02 Malmö, Sweden
| | - Michal Magda
- Section of Protein Chemistry, Department of Translational Medicine, Lund University, 205 02 Malmö, Sweden
| | - Ben C King
- Section of Protein Chemistry, Department of Translational Medicine, Lund University, 205 02 Malmö, Sweden
| | - Ewa Bielecka
- Section of Protein Chemistry, Department of Translational Medicine, Lund University, 205 02 Malmö, Sweden.,Department of Microbiology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Krakow, Poland
| | - Kristian Riesbeck
- Section of Clinical Microbiology, Department of Translational Medicine, Lund University, 202 13 Malmö, Sweden
| | - Sigrun Eick
- Laboratory of Oral Microbiology, Department of Periodontology, University of Bern, 3010 Bern, Switzerland; and
| | - Jan Potempa
- Department of Microbiology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Krakow, Poland.,Centre for Oral Health and Systemic Diseases, University of Louisville School of Dentistry, Louisville, KY 40202
| | - Anna M Blom
- Section of Protein Chemistry, Department of Translational Medicine, Lund University, 205 02 Malmö, Sweden;
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19
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Silva NCS, Vale VF, Franco PF, Gontijo NF, Valenzuela JG, Pereira MH, Sant'Anna MRV, Rodrigues DS, Lima WS, Fux B, Araujo RN. Saliva of Rhipicephalus (Boophilus) microplus (Acari: Ixodidae) inhibits classical and alternative complement pathways. Parasit Vectors 2016; 9:445. [PMID: 27515662 PMCID: PMC4982215 DOI: 10.1186/s13071-016-1726-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 07/25/2016] [Indexed: 01/17/2023] Open
Abstract
Background Rhipicephalus (Boophilus) microplus is the main ectoparasite affecting livestock worldwide. For a successful parasitism, ticks need to evade several immune responses of their hosts, including the activation of the complement system. In spite of the importance of R. microplus, previous work only identified one salivary molecule that blocks the complement system. The current study describes complement inhibitory activities induced by R. microplus salivary components and mechanisms elicited by putative salivary proteins on both classical and alternative complement pathways. Results We found that R. microplus saliva from fully- and partially engorged females was able to inhibit both pathways. Saliva acts strongly at the initial steps of both complement activation pathways. In the classical pathway, the saliva blocked C4 cleavage, and hence, deposition of C4b on the activation surface, suggesting that the inhibition occurs at some point between C1q and C4. In the alternative pathway, saliva acts by binding to initial components of the cascade (C3b and properdin) thereby preventing the C3 convertase formation and reducing C3b production and deposition as well as cleavage of factor B. Saliva has no effect on formation or decay of the C6 to C8 components of the membrane attack complex. Conclusion The saliva of R. microplus is able to inhibit the early steps of classical and alternative pathways of the complement system. Saliva acts by blocking C4 cleavage and deposition of C4b on the classical pathway activation surface and, in the alternative pathway, saliva bind to initial components of the cascade (C3b and properdin) thereby preventing the C3 convertase formation and the production and deposition of additional C3b. Electronic supplementary material The online version of this article (doi:10.1186/s13071-016-1726-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Naylene C S Silva
- Departamento de Parasitologia, Laboratório de Fisiologia de Insetos Hematófagos, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Vladimir F Vale
- Departamento de Parasitologia, Laboratório de Fisiologia de Insetos Hematófagos, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.,Laboratório de Simulídeos e Oncocercose, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, RJ, Brazil
| | - Paula F Franco
- Departamento de Parasitologia, Laboratório de Fisiologia de Insetos Hematófagos, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Nelder F Gontijo
- Departamento de Parasitologia, Laboratório de Fisiologia de Insetos Hematófagos, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.,Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular, Rio de Janeiro, 21941-591, Brazil
| | - Jesus G Valenzuela
- Vector Molecular Biology Section, LMVR, National Institute of Allergy and Infectious Diseases, NIH, Rockville, MD, USA
| | - Marcos H Pereira
- Departamento de Parasitologia, Laboratório de Fisiologia de Insetos Hematófagos, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.,Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular, Rio de Janeiro, 21941-591, Brazil
| | - Mauricio R V Sant'Anna
- Departamento de Parasitologia, Laboratório de Fisiologia de Insetos Hematófagos, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Daniel S Rodrigues
- Empresa de Pesquisa Agropecuária de Minas Gerais, Fazenda Experimental Santa Rita, Rodovia MG 424 km 64, Caixa Postal 295, Prudente de Morais, 35701-970, MG, Brazil
| | - Walter S Lima
- Departamento de Parasitologia, Laboratório de Fisiologia de Insetos Hematófagos, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Blima Fux
- Departamento de Patologia, Universidade Federal do Espírito Santo, Vitória, MG, Brazil
| | - Ricardo N Araujo
- Departamento de Parasitologia, Laboratório de Fisiologia de Insetos Hematófagos, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil. .,Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular, Rio de Janeiro, 21941-591, Brazil.
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20
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Krishnan V. Pilins in gram-positive bacteria: A structural perspective. IUBMB Life 2015; 67:533-43. [PMID: 26178080 DOI: 10.1002/iub.1400] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 06/17/2015] [Indexed: 11/11/2022]
Abstract
Pilins or fimbrilins are a class of proteins found in bacterial surface pilus, a hair-like surface appendage. Both the Gram-negative and -positive bacteria produce pilins to assemble pili on their cell-surface for different purposes including adherence, twitching motility, conjugation, immunomodulation, biofilm formation, and electron transfer. Immunogenic properties of the pilins make them attractive vaccine candidates. The polymerized pilins play a key role in the initiation of host adhesion, which is a critical step for bacterial colonization and infection. Because of their key role in adhesion and exposure on the cell surface, targeting the pilins-mediated adhesion (anti-adhesion therapy) is also seen as a promising alternative approach for preventing and treating bacterial infections, one that may overcome their ever-increasing repertoires of resistance mechanisms. Individual pilins interact with each other non-covalently to assemble the pilus fiber with the help of associated proteins like chaperones and Usher in Gram-negative bacteria. In contrast, the pilins in Gram-positive bacteria often connect with each other covalently, with the help of sortases. Certain unique structural features present on the pilins distinguish them from one another across different bacterial strains, and these dictate their cellular targets and functions. While the structure of pilins has been extensively studied in Gram-negative pathogenic bacteria, the pilins in Gram-positive pathogenic bacteria have been in only during the last decade. Recently, the discovery of pilins in non-pathogenic bacteria, such as Lactobacillus rhamnosus GG, has received great attention, though traditionally the attention was on pathogenic bacteria. This review summarizes and discusses the current structural knowledge of pilins in Gram-positive bacteria with emphasis on those pilins which are sortase substrates.
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Affiliation(s)
- Vengadesan Krishnan
- Regional Centre for Biotechnology, NCR-Biotech Science Cluster, Faridabad-121 001, Haryana, India
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21
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Hasenbein M, Werner I, Deanovic LA, Geist J, Fritsch EB, Javidmehr A, Foe C, Fangue NA, Connon RE. Transcriptomic profiling permits the identification of pollutant sources and effects in ambient water samples. THE SCIENCE OF THE TOTAL ENVIRONMENT 2014; 468-469:688-698. [PMID: 24061060 DOI: 10.1016/j.scitotenv.2013.08.081] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Revised: 08/22/2013] [Accepted: 08/24/2013] [Indexed: 06/02/2023]
Abstract
Contaminant exposure is one possible contributor to population declines of endangered fish species in the Sacramento-San Joaquin Estuary, California, including the endangered delta smelt (Hypomesus transpacificus). Herein we investigated transcriptional responses in larval delta smelt resulting from exposure to water samples collected at the Department of Water Resources Field Station at Hood, a site of concern, situated upstream of known delta smelt habitat and spawning sites and downstream of the Sacramento Regional Wastewater Treatment Plant (SRWTP). Microarray assessments indicate impacts on energy metabolism, DNA repair mechanisms and RNA processing, the immune system, development and muscle function. Transcription responses of fish exposed to water samples from Hood were compared with exposures to 9% effluent samples from SRWTP, water from the Sacramento River at Garcia Bend (SRGB), upstream of the effluent discharge, and SRGB water spiked with 2mg/L total ammonium (9% effluent equivalent). Results indicate that transcriptomic profiles from Hood are similar to 9% SRWTP effluent and ammonium spiked SRGB water, but significantly different from SRGB. SRGB samples however were also significantly different from laboratory controls, suggesting that SRWTP effluent is not solely responsible for the responses determined at Hood, that ammonium exposure likely enhances the effect of multiple-contaminant exposures, and that the observed mortality at Hood is due to the combination of both effluent discharge and contaminants arising from upstream of the tested sites.
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Affiliation(s)
- Matthias Hasenbein
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA; Aquatic Systems Biology Unit, Department of Ecology and Ecosystem Management, Technische Universität München, Mühlenweg 22, D-85354 Freising, Germany; Department of Wildlife, Fish & Conservation Biology, University of California, Davis, CA 95616, USA
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22
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Lovett JE, Abbott RJM, Roversi P, Johnson S, Caesar JJE, Doria M, Jeschke G, Timmel CR, Lea SM. Investigating the structure of the factor B vWF-A domain/CD55 protein-protein complex using DEER spectroscopy: successes and pitfalls. Mol Phys 2013; 111:2865-2872. [PMID: 24954957 PMCID: PMC4056885 DOI: 10.1080/00268976.2013.827754] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Accepted: 07/05/2013] [Indexed: 01/03/2023]
Abstract
The electron paramagnetic resonance technique of double electron-electron resonance (DEER) was used to measure nanometre-scale distances between nitroxide spin labels attached to the complement regulatory protein CD55 (also known as decay accelerating factor) and the von Willebrand factor A (vWF-A) domain of factor B. Following a thorough assessment of the quality of the data, distances obtained from good-quality measurements are compared to predicted distances from a previously hypothesised model for the complex and are found to be incompatible. The success of using these distances as restraints in multi-body docking routines is presented critically.
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Affiliation(s)
- Janet E Lovett
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK ; EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh, UK
| | - Rachel J M Abbott
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Pietro Roversi
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Steven Johnson
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Joseph J E Caesar
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK ; Centre for Advanced Electron Spin Resonance, Inorganic Chemistry Laboratory, University of Oxford, Oxford, UK
| | - Marianna Doria
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK ; Centre for Advanced Electron Spin Resonance, Inorganic Chemistry Laboratory, University of Oxford, Oxford, UK
| | - Gunnar Jeschke
- Laboratory for Physical Chemistry, ETH Zürich, Zürich, Switzerland
| | - Christiane R Timmel
- Centre for Advanced Electron Spin Resonance, Inorganic Chemistry Laboratory, University of Oxford, Oxford, UK
| | - Susan M Lea
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
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Krishnan V, Dwivedi P, Kim BJ, Samal A, Macon K, Ma X, Mishra A, Doran KS, Ton-That H, Narayana SVL. Structure of Streptococcus agalactiae tip pilin GBS104: a model for GBS pili assembly and host interactions. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2013; 69:1073-89. [PMID: 23695252 PMCID: PMC3663123 DOI: 10.1107/s0907444913004642] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Accepted: 02/18/2013] [Indexed: 11/10/2022]
Abstract
The crystal structure of a 75 kDa central fragment of GBS104, a tip pilin from the 2063V/R strain of Streptococcus agalactiae (group B streptococcus; GBS), is reported. In addition, a homology model of the remaining two domains of GBS104 was built and a model of full-length GBS104 was generated by combining the homology model (the N1 and N4 domains) and the crystal structure of the 75 kDa fragment (the N2 and N3 domains). This rod-shaped GBS104 model is constructed of three IgG-like domains (the N1, N2 and N4 domains) and one vWFA-like domain (the N3 domain). The N1 and N2 domains of GBS104 are assembled with distinct and remote segments contributed by the N- and C-termini. The metal-binding site in the N3 domain of GBS104 is in the closed/low-affinity conformation. Interestingly, this domain hosts two long arms that project away from the metal-binding site. Using site-directed mutagenesis, two cysteine residues that lock the N3 domain of GBS104 into the open/high-affinity conformation were introduced. Both wild-type and disulfide-locked recombinant proteins were tested for binding to extracellular matrix proteins such as collagen, fibronectin, fibrinogen and laminin, and an increase in fibronectin binding affinity was identified for the disulfide-locked N3 domain, suggesting that induced conformational changes may play a possible role in receptor binding.
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Affiliation(s)
- Vengadesan Krishnan
- UNESCO Regional Centre for Biotechnology (RCB), Gurgaon 122 016, Haryana, India
| | - Prabhat Dwivedi
- University of Texas Health Science Center, Houston, TX 77030, USA
| | - Brandon J. Kim
- Department of Biology and Center for Microbial Sciences, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182, USA
| | - Alexandra Samal
- Center for Biophysical Sciences and Engineering, School of Optometry, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Kevin Macon
- Center for Biophysical Sciences and Engineering, School of Optometry, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Xin Ma
- University of Texas Health Science Center, Houston, TX 77030, USA
| | - Arunima Mishra
- University of Texas Health Science Center, Houston, TX 77030, USA
| | - Kelly S. Doran
- Department of Biology and Center for Microbial Sciences, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182, USA
| | - Hung Ton-That
- University of Texas Health Science Center, Houston, TX 77030, USA
| | - Sthanam V. L. Narayana
- Center for Biophysical Sciences and Engineering, School of Optometry, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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Abstract
Protein C is activated by thrombin with a value of k(cat)/K(m) = 0.11mM(-1)s(-1) that increases 1700-fold in the presence of the cofactor thrombomodulin. The molecular origin of this effect triggering an important feedback loop in the coagulation cascade remains elusive. Acidic residues in the activation domain of protein C are thought to electrostatically clash with the active site of thrombin. However, functional and structural data reported here support an alternative scenario. The thrombin precursor prethrombin-2 has R15 at the site of activation in ionic interaction with E14e, D14l, and E18, instead of being exposed to solvent for proteolytic attack. Residues E160, D167, and D172 around the site of activation at R169 of protein C occupy the same positions as E14e, D14l, and E18 in prethrombin-2. Caging of R169 by E160, D167, and D172 is responsible for much of the poor activity of thrombin toward protein C. The E160A/D167A/D172A mutant is activated by thrombin 63-fold faster than wild-type in the absence of thrombomodulin and, over a slower time scale, spontaneously converts to activated protein C. These findings establish a new paradigm for cofactor-assisted reactions in the coagulation cascade.
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25
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Garcia BL, Ramyar KX, Ricklin D, Lambris JD, Geisbrecht BV. Advances in understanding the structure, function, and mechanism of the SCIN and Efb families of Staphylococcal immune evasion proteins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 946:113-33. [PMID: 21948365 DOI: 10.1007/978-1-4614-0106-3_7] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Our understanding of both the nature and diversity of Staphylococcal immune evasion proteins has increased tremendously throughout the last several years. Among this group of molecules, members of the SCIN and Efb families of complement inhibitors have been the subject of particularly intense study. This work has demonstrated that both types of proteins exert their primary function by inhibiting C3 convertases, which lie at the heart of the complement-mediated immune response. Despite this similarity, however, significant differences in structure/function relationships and mechanisms of action exist between these bacterial proteins. Furthermore, divergent secondary effects on host immune responses have also been described for these two protein families. This chapter summarizes recent advances toward understanding the structure, function, and mechanism of the SCIN and Efb families, and suggests potential directions for the field over the coming years.
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Affiliation(s)
- Brandon L Garcia
- School of Biological Sciences, University of Missouri, Kansas City, MO 64110, USA.
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26
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Pozzi N, Chen Z, Zapata F, Pelc LA, Barranco-Medina S, Di Cera E. Crystal structures of prethrombin-2 reveal alternative conformations under identical solution conditions and the mechanism of zymogen activation. Biochemistry 2011; 50:10195-202. [PMID: 22049947 DOI: 10.1021/bi2015019] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Prethrombin-2 is the immediate zymogen precursor of the clotting enzyme thrombin, which is generated upon cleavage at R15 and separation of the A chain and catalytic B chain. The X-ray structure of prethrombin-2 determined in the free form at 1.9 Å resolution shows the 215-217 segment collapsed into the active site and occluding 49% of the volume available for substrate binding. Remarkably, some of the crystals harvested from the same crystallization well, under identical solution conditions, diffract to 2.2 Å resolution in the same space group but produce a structure in which the 215-217 segment moves >5 Å and occludes 24% of the volume available for substrate binding. The two alternative conformations of prethrombin-2 have the side chain of W215 relocating >9 Å within the active site and are relevant to the allosteric E*-E equilibrium of the mature enzyme. Another unanticipated feature of prethrombin-2 bears on the mechanism of prothrombin activation. R15 is found buried within the protein in ionic interactions with E14e, D14l, and E18, thereby making its exposure to solvent necessary for proteolytic attack and conversion to thrombin. On the basis of this structural observation, we constructed the E14eA/D14lA/E18A triple mutant to reduce the level of electrostatic coupling with R15 and promote zymogen activation. The mutation causes prethrombin-2 to spontaneously convert to thrombin, without the need for the snake venom ecarin or the physiological prothrombinase complex.
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Affiliation(s)
- Nicola Pozzi
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, Missouri 63104, United States
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27
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Design and development of TT30, a novel C3d-targeted C3/C5 convertase inhibitor for treatment of human complement alternative pathway-mediated diseases. Blood 2011; 118:4705-13. [PMID: 21860027 DOI: 10.1182/blood-2011-06-359646] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
To selectively modulate human complement alternative pathway (CAP) activity implicated in a wide range of acute and chronic inflammatory conditions and to provide local cell surface and tissue-based inhibition of complement-induced damage, we developed TT30, a novel therapeutic fusion protein linking the human complement receptor type 2 (CR2/CD21) C3 fragment (C3frag = iC3b, C3dg, C3d)-binding domain with the CAP inhibitory domain of human factor H (fH). TT30 efficiently blocks ex vivo CAP-dependent C3frag accumulation on activated surfaces, membrane attack complex (MAC) formation and hemolysis of RBCs in a CR2-dependent manner, and with a ∼ 150-fold potency gain over fH, without interference of C3 activation or MAC formation through the classic and lectin pathways. TT30 protects RBCs from hemolysis and remains bound and detectable for at least 24 hours. TT30 selectively inhibits CAP in cynomolgus monkeys and is bioavailable after subcutaneous injection. Using a unique combination of targeting and effector domains, TT30 controls cell surface CAP activation and has substantial potential utility for the treatment of human CAP-mediated diseases.
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28
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Allostery in trypsin-like proteases suggests new therapeutic strategies. Trends Biotechnol 2011; 29:577-85. [PMID: 21726912 DOI: 10.1016/j.tibtech.2011.06.001] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2011] [Revised: 05/19/2011] [Accepted: 06/02/2011] [Indexed: 11/21/2022]
Abstract
Trypsin-like proteases (TLPs) are a large family of enzymes responsible for digestion, blood coagulation, fibrinolysis, development, fertilization, apoptosis and immunity. A current paradigm posits that the irreversible transition from an inactive zymogen to the active protease form enables productive interaction with substrate and catalysis. Analysis of the entire structural database reveals two distinct conformations of the active site: one fully accessible to substrate (E) and the other occluded by the collapse of a specific segment (E*). The allosteric E*-E equilibrium provides a reversible mechanism for activity and regulation in addition to the irreversible zymogen to protease conversion and points to new therapeutic strategies aimed at inhibiting or activating the enzyme. In this review, we discuss relevant examples, with emphasis on the rational engineering of anticoagulant thrombin mutants.
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29
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Niu W, Chen Z, Gandhi PS, Vogt AD, Pozzi N, Pelc LA, Zapata F, Di Cera E. Crystallographic and kinetic evidence of allostery in a trypsin-like protease. Biochemistry 2011; 50:6301-7. [PMID: 21707111 DOI: 10.1021/bi200878c] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Protein allostery is based on the existence of multiple conformations in equilibrium linked to distinct functional properties. Although evidence of allosteric transitions is relatively easy to identify by functional studies, structural detection of a pre-existing equilibrium between alternative conformations remains challenging even for textbook examples of allosteric proteins. Kinetic studies show that the trypsin-like protease thrombin exists in equilibrium between two conformations where the active site is either collapsed (E*) or accessible to substrate (E). However, structural demonstration that the two conformations exist in the same enzyme construct free of ligands has remained elusive. Here we report the crystal structure of the thrombin mutant N143P in the E form, which complements the recently reported structure in the E* form, and both the E and E* forms of the thrombin mutant Y225P. The side chain of W215 moves 10.9 Å between the two forms, causing a displacement of 6.6 Å of the entire 215-217 segment into the active site that in turn opens or closes access to the primary specificity pocket. Rapid kinetic measurements of p-aminobenzamidine binding to the active site confirm the existence of the E*-E equilibrium in solution for wild-type and the mutants N143P and Y225P. These findings provide unequivocal proof of the allosteric nature of thrombin and lend strong support to the recent proposal that the E*-E equilibrium is a key property of the trypsin fold.
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Affiliation(s)
- Weiling Niu
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, Missouri 63104, USA
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30
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Vengadesan K, Narayana SVL. Structural biology of Gram-positive bacterial adhesins. Protein Sci 2011; 20:759-72. [PMID: 21404359 DOI: 10.1002/pro.613] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Revised: 02/16/2011] [Accepted: 02/21/2011] [Indexed: 11/08/2022]
Abstract
The structural biology of Gram-positive cell surface adhesins is an emerging field of research, whereas Gram-negative pilus assembly and anchoring have been extensively investigated and are well understood. Gram-positive surface proteins known as MSCRAMMs (microbial surface components recognizing adhesive matrix molecules) and individual proteins that assemble into long, hair-like organelles known as pili have similar features at the primary sequence level as well as at the tertiary structural level. Some of these conserved features are essential for their transportation from the cytoplasm and for cell wall anchoring. More importantly, the MSCRAMMs and the individual pilins are assembled with building blocks that are variants of structural modules used for human immunoglobulins. MSCRAMMs target the host's extracellular matrix proteins, such as collagen, fibrinogen, and fibronectin, and they have received considerable attention from structural biologists in the last decade, who have primarily been interested in understanding their interactions with host tissue. The recent focus is on the newly discovered pili of Gram-positive bacteria, and in this review, we highlight the advances in understanding of the individual pilus constituents and their associations and stress the similarities between the individual pilins and surface proteins.
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Affiliation(s)
- Krishnan Vengadesan
- School of Optometry and Center for Biophysical Sciences and Engineering, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
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31
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Di Cera E. Thrombin as an Anticoagulant. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2011; 99:145-84. [DOI: 10.1016/b978-0-12-385504-6.00004-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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32
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Abstract
Prothrombin is the zymogen precursor of the clotting enzyme thrombin, which is generated by two sequential cleavages at R271 and R320 by the prothrombinase complex. The structure of prothrombin is currently unknown. Prethrombin-1 differs from prothrombin for the absence of 155 residues in the N-terminal domain and is composed of a single polypeptide chain containing fragment 2 (residues 156-271), A chain (residues 272-320), and B chain (residues 321-579). The X-ray crystal structure of prethrombin-1 solved at 2.2-Å resolution shows an overall conformation significantly different (rmsd = 3.6 Å) from that of its active form meizothrombin desF1 carrying a cleavage at R320. Fragment 2 is rotated around the y axis by 29° and makes only few contacts with the B chain. In the B chain, the oxyanion hole is disrupted due to absence of the I16-D194 ion pair and the Na(+) binding site and adjacent primary specificity pocket are highly perturbed. A remarkable feature of the structure is that the autolysis loop assumes a helical conformation enabling W148 and W215, located 17 Å apart in meizothrombin desF1, to come within 3.3 Å of each other and completely occlude access to the active site. These findings suggest that the zymogen form of thrombin possesses conformational plasticity comparable to that of the mature enzyme and have significant implications for the mechanism of prothrombin activation and the zymogen → protease conversion in trypsin-like proteases.
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33
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Rodríguez de Córdoba S, Harris CL, Morgan BP, Llorca O. Lessons from functional and structural analyses of disease-associated genetic variants in the complement alternative pathway. Biochim Biophys Acta Mol Basis Dis 2010; 1812:12-22. [PMID: 20837143 DOI: 10.1016/j.bbadis.2010.09.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2010] [Revised: 09/03/2010] [Accepted: 09/07/2010] [Indexed: 11/15/2022]
Abstract
Complement is an essential component of innate immunity and a major trigger of inflammatory responses. A critical step in complement activation is the formation of the C3 convertase of the alternative pathway (AP), a labile bimolecular complex formed by activated fragments of the C3 and factor B components that is fundamental to provide exponential amplification of the initial complement trigger. Regulation of the AP C3 convertase is essential to maintain complement homeostasis in plasma and to protect host cells and tissues from damage by complement. During the last decade, several studies have associated genetic variations in components and regulators of the AP C3 convertase with a number of chronic inflammatory diseases and susceptibility to infection. The functional characterization of these protein variants has helped to decipher the critical pathogenic mechanisms involved in some of these complement related disorders. In addition, these functional data together with recent 3D structures of the AP C3 convertase have provided fundamental insights into the assembly, activation and regulation of the AP C3 convertase.
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Affiliation(s)
- Santiago Rodríguez de Córdoba
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Ramiro de Maeztu 9, 28040 Madrid, Spain.
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34
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Vogt AD, Bah A, Di Cera E. Evidence of the E*-E equilibrium from rapid kinetics of Na+ binding to activated protein C and factor Xa. J Phys Chem B 2010; 114:16125-30. [PMID: 20809655 DOI: 10.1021/jp105502c] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Na(+) binding to thrombin enhances the procoagulant and prothrombotic functions of the enzyme and obeys a mechanism that produces two kinetic phases: one fast (in the microsecond time scale) due to Na(+) binding to the low activity form E to produce the high activity form E:Na(+) and another considerably slower (in the millisecond time scale) that reflects a pre-equilibrium between E and the inactive form E*. In this study, we demonstrate that this mechanism also exists in other Na(+)-activated clotting proteases like factor Xa and activated protein C. These findings, along with recent structural data, suggest that the E*-E equilibrium is a general feature of the trypsin fold.
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Affiliation(s)
- Austin D Vogt
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, Missouri 63104, USA
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35
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The structure of tumor endothelial marker 8 (TEM8) extracellular domain and implications for its receptor function for recognizing anthrax toxin. PLoS One 2010; 5:e11203. [PMID: 20585457 PMCID: PMC2887854 DOI: 10.1371/journal.pone.0011203] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2010] [Accepted: 05/20/2010] [Indexed: 12/02/2022] Open
Abstract
Anthrax toxin, which is released from the Gram-positive bacterium Bacillus anthracis, is composed of three proteins: protective antigen (PA), lethal factor (LF), and edema factor (EF). PA binds a receptor on the surface of the target cell and further assembles into a homo-heptameric pore through which EF and LF translocate into the cytosol. Two distinct cellular receptors for anthrax toxin, TEM8/ANTXR1 and CMG2/ANTXR2, have been identified, and it is known that their extracellular domains bind PA with low and high affinities, respectively. Here, we report the crystal structure of the TEM8 extracellular vWA domain at 1.7 Å resolution. The overall structure has a typical integrin fold and is similar to that of the previously published CMG2 structure. In addition, using structure-based mutagenesis, we demonstrate that the putative interface region of TEM8 with PA (consisting of residues 56, 57, and 154–160) is responsible for the PA-binding affinity differences between the two receptors. In particular, Leu56 was shown to be a key factor for the lower affinity of TEM8 towards PA compared with CMG2. Because of its high affinity for PA and low expression in normal tissues, an isolated extracellular vWA domain of the L56A TEM8 variant may serve as a potent antitoxin and a potential therapeutic treatment for anthrax infection. Moreover, as TEM8 is often over-expressed in tumor cells, our TEM8 crystal structure may provide new insights into how to design PA mutants that preferentially target tumor cells.
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36
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Molecular mechanisms of complement evasion: learning from staphylococci and meningococci. Nat Rev Microbiol 2010; 8:393-9. [PMID: 20467445 DOI: 10.1038/nrmicro2366] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The complement system is a crucial component of the innate immune response in humans. Recent studies in Staphylococcus aureus and Neisseria meningitidis have revealed how these bacteria escape complement-mediated killing. In addition, new structural data have provided detailed insights into the molecular mechanisms of host defence mediated by the complement system and how bacterial proteins interfere with this process. This information is fundamental to our understanding of bacterial pathogenesis and may facilitate the design of better vaccines.
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37
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Kadam AP, Sahu A. Identification of Complin, a novel complement inhibitor that targets complement proteins factor B and C2. THE JOURNAL OF IMMUNOLOGY 2010; 184:7116-24. [PMID: 20483772 DOI: 10.4049/jimmunol.1000200] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Complement factor B (fB) is a key constituent of the alternative pathway (AP). Its central role in causing inflammation and tissue injury through activation of the AP urges the need for its therapeutic targeting. In the current study, we have screened phage-displayed random peptide libraries against fB and identified a novel cyclic hendecapeptide that inhibits activation of fB and the AP. Structure-activity studies revealed that: 1) the cysteine-constrained structure of the peptide is essential for its activity; 2) Ile5, Arg6, Leu7, and Tyr8 contribute significantly to its inhibitory activity; and 3) retro-inverso modification of the peptide results in loss of its activity. Binding studies performed using surface plasmon resonance suggested that the peptide has two binding sites on fB, which are located on the Ba and Bb fragments. Studies on the mechanism of inhibition revealed that the peptide does not block the interaction of fB with the activated form of C3, thereby suggesting that the peptide inhibits fB activation primarily by inhibiting its cleavage by factor D. The peptide showed a weak effect on preformed C3 and C5 convertases. Like inhibition of fB cleavage, the peptide also inhibited C2 cleavage by activated C1s and activation of the classical as well as lectin pathways. Based on its inhibitory activities, we named the peptide Complin.
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Affiliation(s)
- Archana P Kadam
- National Centre for Cell Science, Pune University Campus, Ganeshkhind, Pune, India
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38
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Tawadrous H, Maga T, Sharma J, Kupferman J, Smith RJH, Schoeneman M. A novel mutation in the complement factor B gene (CFB) and atypical hemolytic uremic syndrome. Pediatr Nephrol 2010; 25:947-51. [PMID: 20108004 DOI: 10.1007/s00467-009-1415-3] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2009] [Revised: 11/13/2009] [Accepted: 11/27/2009] [Indexed: 01/28/2023]
Abstract
We report the case of an 8-year-old girl diagnosed with atypical hemolytic uremic syndrome (aHUS) with a complement factor B (CFB) gene mutation. aHUS is a disease of complement dysregulation. In approximately 50% of patients, mutations are identified in genes encoding regulators of complement-complement factor H (CFH), membrane cofactor protein or complement factor I (CFI)-or activators of complement-complement factor B (CFB) or C3. The mutation in this patient was identified in exon 12 of CFB and changes a lysine at amino acid position 533 to an arginine (c.1598A>G p.Lys533Arg). The two other mutations previously reported in CFB associated with aHUS are c.858C>G, p.F286L in exon 6 and c.967A>Gp.K323E in exon 7.
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Affiliation(s)
- Hanan Tawadrous
- Division of Pediatric Nephrology, SUNY Downstate Medical Center, Brooklyn, NY 11203, USA.
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39
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Niu W, Chen Z, Bush-Pelc LA, Bah A, Gandhi PS, Di Cera E. Mutant N143P reveals how Na+ activates thrombin. J Biol Chem 2009; 284:36175-36185. [PMID: 19846563 PMCID: PMC2794733 DOI: 10.1074/jbc.m109.069500] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2009] [Revised: 10/12/2009] [Indexed: 01/09/2023] Open
Abstract
The molecular mechanism of thrombin activation by Na(+) remains elusive. Its kinetic formulation requires extension of the classical Botts-Morales theory for the action of a modifier on an enzyme to correctly account for the contribution of the E*, E, and E:Na(+) forms. The extended scheme establishes that analysis of k(cat) unequivocally identifies allosteric transduction of Na(+) binding into enhanced catalytic activity. The thrombin mutant N143P features no Na(+)-dependent enhancement of k(cat) yet binds Na(+) with an affinity comparable to that of wild type. Crystal structures of the mutant in the presence and absence of Na(+) confirm that Pro(143) abrogates the important H-bond between the backbone N atom of residue 143 and the carbonyl O atom of Glu(192), which in turn controls the orientation of the Glu(192)-Gly(193) peptide bond and the correct architecture of the oxyanion hole. We conclude that Na(+) activates thrombin by securing the correct orientation of the Glu(192)-Gly(193) peptide bond, which is likely flipped in the absence of cation. Absolute conservation of the 143-192 H-bond in trypsin-like proteases and the importance of the oxyanion hole in protease function suggest that this mechanism of Na(+) activation is present in all Na(+)-activated trypsin-like proteases.
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Affiliation(s)
- Weiling Niu
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Zhiwei Chen
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Leslie A Bush-Pelc
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Alaji Bah
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Prafull S Gandhi
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Enrico Di Cera
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110.
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40
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Ruiz-Gómez G, Lim J, Halili MA, Le GT, Madala PK, Abbenante G, Fairlie DP. Structure-activity relationships for substrate-based inhibitors of human complement factor B. J Med Chem 2009; 52:6042-52. [PMID: 19743866 DOI: 10.1021/jm900781m] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Human complement is a cascading network of plasma proteins important in immune defense, cooperatively effecting recognition, opsonization, destruction, and removal of pathogens and infected/damaged cells. Overstimulated or unregulated complement activation can result in immunoinflammatory diseases. Key serine proteases in this cascade are difficult to study due to their multiprotein composition, short lifetimes, formation on membranes, or serum circulation as inactive zymogens. Factor B is inactive at pH 7, but a catalytically active serine protease under alkaline conditions, enabling structure-activity relationship studies for 63 substrate-based peptide inhibitors with 4-7 residues and a C-terminal aldehyde. A potent factor B inhibitor was hexpeptide Ac-RLTbaLAR-H (IC(50) 250 nM, pH 9.5), which at pH 7 also blocked formation of membrane attack complex via the "alternative pathway" of complement activation and inhibited human complement mediated lysis of rabbit erythrocytes. Inhibitors of factor B may be valuable probes and drug leads for complement mediated immunity and disease.
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Affiliation(s)
- Gloria Ruiz-Gómez
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
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41
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Wei W, Wu H, Xu H, Xu T, Zhang X, Chang K, Zhang Y. Cloning and molecular characterization of two complement Bf/C2 genes in large yellow croaker (Pseudosciaena crocea). FISH & SHELLFISH IMMUNOLOGY 2009; 27:285-295. [PMID: 19490942 DOI: 10.1016/j.fsi.2009.05.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2009] [Revised: 05/20/2009] [Accepted: 05/24/2009] [Indexed: 05/27/2023]
Abstract
Complement components factor B and C2 are two crucial proteases in the alternative pathway (AP) and classical pathway (CP). Two Bf/C2 cDNAs, LycBf/C2A and LycBf/C2B were isolated from the large yellow croaker (Pseudosciaena crocea) by suppression subtractive hybridization (SSH) and rapid amplification of cDNA ends (RACE). Through sequence alignment and computer 3D modeling analysis, we found that both of the deduced proteins contain three complement control protein (CCP) modules, a von Willebrand factor A (vWFA) domain, and one serine protease (SP) domain. Both structural analysis and phylogenetic analyses suggested that LycBf/C2A is more like human factor B than human C2 while LycBf/C2B is more human C2-like. After that, RT-PCR assay showed that LycBf/C2A and LycBf/C2B were mostly expressed in liver, albeit detectable in other tissues. Finally, after being infected with attenuated live Vibrio anguillarum strain, the expression level of LycBf/C2A and LycBf/C2B were found remarkably up-regulated in liver, spleen and kidney, indicating that the two complement factors play a pivotal role in the immune response to bacterial challenge in large yellow croaker.
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Affiliation(s)
- Wei Wei
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, PR China
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42
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Abstract
Over one third of all known proteolytic enzymes are serine proteases. Among these, the trypsins underwent the most predominant genetic expansion yielding the enzymes responsible for digestion, blood coagulation, fibrinolysis, development, fertilization, apoptosis, and immunity. The success of this expansion resides in a highly efficient fold that couples catalysis and regulatory interactions. Added complexity comes from the recent observation of a significant conformational plasticity of the trypsin fold. A new paradigm emerges where two forms of the protease, E* and E, are in allosteric equilibrium and determine biological activity and specificity.
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Affiliation(s)
- Enrico Di Cera
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Box 8231, St. Louis, MO 63110, USA.
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43
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Gandhi PS, Page MJ, Chen Z, Bush-Pelc L, Di Cera E. Mechanism of the anticoagulant activity of thrombin mutant W215A/E217A. J Biol Chem 2009; 284:24098-105. [PMID: 19586901 DOI: 10.1074/jbc.m109.025403] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The thrombin mutant W215A/E217A (WE) is a potent anticoagulant both in vitro and in vivo. Previous x-ray structural studies have shown that WE assumes a partially collapsed conformation that is similar to the inactive E* form, which explains its drastically reduced activity toward substrate. Whether this collapsed conformation is genuine, rather than the result of crystal packing or the mutation introduced in the critical 215-217 beta-strand, and whether binding of thrombomodulin to exosite I can allosterically shift the E* form to the active E form to restore activity toward protein C are issues of considerable mechanistic importance to improve the design of an anticoagulant thrombin mutant for therapeutic applications. Here we present four crystal structures of WE in the human and murine forms that confirm the collapsed conformation reported previously under different experimental conditions and crystal packing. We also present structures of human and murine WE bound to exosite I with a fragment of the platelet receptor PAR1, which is unable to shift WE to the E form. These structural findings, along with kinetic and calorimetry data, indicate that WE is strongly stabilized in the E* form and explain why binding of ligands to exosite I has only a modest effect on the E*-E equilibrium for this mutant. The E* --> E transition requires the combined binding of thrombomodulin and protein C and restores activity of the mutant WE in the anticoagulant pathway.
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Affiliation(s)
- Prafull S Gandhi
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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44
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Janssen BJC, Gomes L, Koning RI, Svergun DI, Koster AJ, Fritzinger DC, Vogel CW, Gros P. Insights into complement convertase formation based on the structure of the factor B-cobra venom factor complex. EMBO J 2009; 28:2469-78. [PMID: 19574954 DOI: 10.1038/emboj.2009.184] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2009] [Accepted: 06/08/2009] [Indexed: 11/09/2022] Open
Abstract
Immune protection by the complement system critically depends on assembly of C3 convertases on the surface of pathogens and altered host cells. These short-lived protease complexes are formed through pro-convertases, which for the alternative pathway consist of the complement component C3b and the pro-enzyme factor B (FB). Here, we present the crystal structure at 2.2-A resolution, small-angle X-ray scattering and electron microscopy (EM) data of the pro-convertase formed by human FB and cobra venom factor (CVF), a potent homologue of C3b that generates more stable convertases. FB is loaded onto CVF through its pro-peptide Ba segment by specific contacts, which explain the specificity for the homologous C3b over the native C3 and inactive products iC3b and C3c. The protease segment Bb binds the carboxy terminus of CVF through the metal-ion dependent adhesion site of the Von Willebrand factor A-type domain. A possible dynamic equilibrium between a 'loading' and 'activation' state of the pro-convertase may explain the observed difference between the crystal structure of CVFB and the EM structure of C3bB. These insights into formation of convertases provide a basis for further development of complement therapeutics.
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Affiliation(s)
- Bert J C Janssen
- Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Utrecht, The Netherlands
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45
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Structural and functional implications of the alternative complement pathway C3 convertase stabilized by a staphylococcal inhibitor. Nat Immunol 2009; 10:721-7. [PMID: 19503103 PMCID: PMC2729104 DOI: 10.1038/ni.1756] [Citation(s) in RCA: 175] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2009] [Accepted: 05/15/2009] [Indexed: 12/30/2022]
Abstract
Activation of the complement system generates potent chemoattractants and opsonizes cells for immune clearance. Short-lived protease complexes cleave complement component C3 into anaphylatoxin C3a and opsonin C3b. Here we report the crystal structure of the C3 convertase formed by C3b and the protease fragment Bb, which was stabilized by the bacterial immune-evasion protein SCIN. The data suggest that the proteolytic specificity and activity depends on dimerization of C3 with C3b of the convertase. SCIN blocked the formation of a productive enzyme-substrate complex. Irreversible dissociation of C3bBb is crucial to complement regulation and was determined by slow binding kinetics of the Mg2+-adhesion site in Bb. Understanding the mechanistic basis of the central complement activation step and microbial immune evasion strategies targeting this step will aid the development of complement therapeutics.
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46
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Bah A, Carrell CJ, Chen Z, Gandhi PS, Di Cera E. Stabilization of the E* form turns thrombin into an anticoagulant. J Biol Chem 2009; 284:20034-40. [PMID: 19473969 DOI: 10.1074/jbc.m109.012344] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Previous studies have shown that deletion of nine residues in the autolysis loop of thrombin produces a mutant with an anticoagulant propensity of potential clinical relevance, but the molecular origin of the effect has remained unresolved. The x-ray crystal structure of this mutant solved in the free form at 1.55 A resolution reveals an inactive conformation that is practically identical (root mean square deviation of 0.154 A) to the recently identified E* form. The side chain of Trp(215) collapses into the active site by shifting > 10 A from its position in the active E form, and the oxyanion hole is disrupted by a flip of the Glu(192)-Gly(193) peptide bond. This finding confirms the existence of the inactive form E* in essentially the same incarnation as first identified in the structure of the thrombin mutant D102N. In addition, it demonstrates that the anticoagulant profile often caused by a mutation of the thrombin scaffold finds its likely molecular origin in the stabilization of the inactive E* form that is selectively shifted to the active E form upon thrombomodulin and protein C binding.
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Affiliation(s)
- Alaji Bah
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Krishnan V, Xu Y, Macon K, Volanakis JE, Narayana SVL. The structure of C2b, a fragment of complement component C2 produced during C3 convertase formation. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2009; 65:266-74. [PMID: 19237749 DOI: 10.1107/s0907444909000389] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2008] [Accepted: 01/05/2009] [Indexed: 11/11/2022]
Abstract
The second component of complement (C2) is a multi-domain serine protease that provides catalytic activity for the C3 and C5 convertases of the classical and lectin pathways of human complement. The formation of these convertases requires the Mg(2+)-dependent binding of C2 to C4b and the subsequent cleavage of C2 by C1s or MASP2, respectively. The crystal structure of full-length C2 is not yet available, although the structure of its C-terminal catalytic segment C2a has been determined. The crystal structure of the N-terminal segment C2b of C2 determined to 1.8 A resolution presented here reveals the arrangement of its three CCP domains. The domains are arranged differently compared with most other CCP-domain assemblies, but their arrangement is similar to that found in the Ba part of the full-length factor B structure. The crystal structures of C2a, C2b and full-length factor B are used to generate a model for C2 and a discussion of the domain association and possible interactions with C4b during formation of the C4b-C2 complex is presented. The results of this study also suggest that upon cleavage by C1s, C2a domains undergo conformational rotation while bound to C4b and the released C2b domains may remain folded together similar to as observed in the intact protein.
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Affiliation(s)
- Vengadesan Krishnan
- Center for Biophysical Sciences and Engineering, School of Optometry, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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3D structure of the C3bB complex provides insights into the activation and regulation of the complement alternative pathway convertase. Proc Natl Acad Sci U S A 2009; 106:882-7. [PMID: 19136636 DOI: 10.1073/pnas.0810860106] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Generation of the alternative pathway C3-convertase, the central amplification enzyme of the complement cascade, initiates by the binding of factor B (fB) to C3b to form the proconvertase, C3bB. C3bB is subsequently cleaved by factor D (fD) at a single site in fB, producing Ba and Bb fragments. Ba dissociates from the complex, while Bb remains bound to C3b, forming the active alternative pathway convertase, C3bBb. Using single-particle electron microscopy we have determined the 3-dimensional structures of the C3bB and the C3bBb complexes at approximately 27A resolution. The C3bB structure shows that fB undergoes a dramatic conformational change upon binding to C3b. However, the C3b-bound fB structure was easily interpreted after independently fitting the atomic structures of the isolated Bb and Ba fragments. Interestingly, the divalent cation-binding site in the von Willebrand type A domain in Bb faces the C345C domain of C3b, whereas the serine-protease domain of Bb points outwards. The structure also shows that the Ba fragment interacts with C3b separately from Bb at the level of the alpha'NT and CUB domains. Within this conformation, the long and flexible linker between Bb and Ba is likely exposed and accessible for cleavage by fD to form the active convertase, C3bBb. The architecture of the C3bB and C3bBb complexes reveals that C3b could promote cleavage and activation of fB by actively displacing the Ba domain from the von Willebrand type A domain in free fB. These structures provide a structural basis to understand fundamental aspects of the activation and regulation of the alternative pathway C3-convertase.
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Jongerius I, Ram S, Rooijakkers S. Bacterial complement escape. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2009; 666:32-48. [PMID: 20054973 DOI: 10.1007/978-1-4419-1601-3_3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Complement activation is a crucial step in our innate immune defense against invading bacteria. Complement proteins can quickly recognize invading bacteria and subsequently label them for phagocytosis or kill them by direct lysis. In order to survive in the human host, bacterial pathogens have evolved a number of excreted and membrane-bound proteins that interfere with several steps of the complement cascade. In this chapter we summarize the most successful complement-modulating strategies by human bacterial pathogens.
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Affiliation(s)
- Ilse Jongerius
- Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands
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50
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Abstract
Complement in mammalian plasma recognizes pathogenic, immunogenic and apoptotic cell surfaces, promotes inflammatory responses and marks particles for cell lysis, phagocytosis and B-cell stimulation. At the heart of the complement system are two large proteins, complement component C3 and protease factor B. These two proteins are pivotal for amplification of the complement response and for labelling of the target particles, steps that are required for effective clearance of the target. Here we review the molecular mechanisms of complement activation, in which proteolysis and complex formation result in large conformational changes that underlie the key offensive step of complement executed by C3 and factor B. Insights into the mechanisms of complement amplification are crucial for understanding host defence and pathogen immune evasion, and for the development of complement-immune therapies.
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