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Tamamis P, Kieslich CA, Nikiforovich GV, Woodruff TM, Morikis D, Archontis G. Insights into the mechanism of C5aR inhibition by PMX53 via implicit solvent molecular dynamics simulations and docking. BMC BIOPHYSICS 2014; 7:5. [PMID: 25170421 PMCID: PMC4141665 DOI: 10.1186/2046-1682-7-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Accepted: 06/30/2014] [Indexed: 01/31/2023]
Abstract
Background The complement protein C5a acts by primarily binding and activating the G-protein coupled C5a receptor C5aR (CD88), and is implicated in many inflammatory diseases. The cyclic hexapeptide PMX53 (sequence Ace-Phe-[Orn-Pro-dCha-Trp-Arg]) is a full C5aR antagonist of nanomolar potency, and is widely used to study C5aR function in disease. Results We construct for the first time molecular models for the C5aR:PMX53 complex without the a priori use of experimental constraints, via a computational framework of molecular dynamics (MD) simulations, docking, conformational clustering and free energy filtering. The models agree with experimental data, and are used to propose important intermolecular interactions contributing to binding, and to develop a hypothesis for the mechanism of PMX53 antagonism. Conclusion This work forms the basis for the design of improved C5aR antagonists, as well as for atomic-detail mechanistic studies of complement activation and function. Our computational framework can be widely used to develop GPCR-ligand structural models in membrane environments, peptidomimetics and other chemical compounds with potential clinical use.
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Affiliation(s)
- Phanourios Tamamis
- Department of Physics, University of Cyprus, PO 20537, CY1678 Nicosia, Cyprus
| | - Chris A Kieslich
- Department of Bioengineering, University of California, Riverside, CA 92521, USA
| | | | - Trent M Woodruff
- School of Biomedical Sciences, the University of Queensland, St Lucia 4072, Australia
| | - Dimitrios Morikis
- Department of Bioengineering, University of California, Riverside, CA 92521, USA
| | - Georgios Archontis
- Department of Physics, University of Cyprus, PO 20537, CY1678 Nicosia, Cyprus
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Klos A, Wende E, Wareham KJ, Monk PN. International Union of Basic and Clinical Pharmacology. [corrected]. LXXXVII. Complement peptide C5a, C4a, and C3a receptors. Pharmacol Rev 2013; 65:500-43. [PMID: 23383423 DOI: 10.1124/pr.111.005223] [Citation(s) in RCA: 178] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The activation of the complement cascade, a cornerstone of the innate immune response, produces a number of small (74-77 amino acid) fragments, originally termed anaphylatoxins, that are potent chemoattractants and secretagogues that act on a wide variety of cell types. These fragments, C5a, C4a, and C3a, participate at all levels of the immune response and are also involved in other processes such as neural development and organ regeneration. Their primary function, however, is in inflammation, so they are important targets for the development of antiinflammatory therapies. Only three receptors for complement peptides have been found, but there are no satisfactory antagonists as yet, despite intensive investigation. In humans, there is a single receptor for C3a (C3a receptor), no known receptor for C4a, and two receptors for C5a (C5a₁ receptor and C5a₂ receptor). The most recently characterized receptor, the C5a₂ receptor (previously known as C5L2 or GPR77), has been regarded as a passive binding protein, but signaling activities are now ascribed to it, so we propose that it be formally identified as a receptor and be given a name to reflect this. Here, we describe the complex biology of the complement peptides, introduce a new suggested nomenclature, and review our current knowledge of receptor pharmacology.
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Affiliation(s)
- Andreas Klos
- Department for Medical Microbiology, Medical School Hannover, Hannover, Germany
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Lu X, Xia M, Endresz V, Faludi I, Mundkur L, Gonczol E, Chen D, Kakkar VV. Immunization With a Combination of 2 Peptides Derived From the C5a Receptor Significantly Reduces Early Atherosclerotic Lesion in
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J Mice. Arterioscler Thromb Vasc Biol 2012; 32:2358-71. [DOI: 10.1161/atvbaha.112.253179] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Objective—
The goal of this study was to assess whether immunization of
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J mice with 2 peptides located at the N-terminus of the C5a receptor (C5aR), either alone or in combination, is effective in reducing atherosclerotic lesions.
Methods and Results—
Five- to 6-week-old female
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J mice were immunized using a repetitive immunization multiple sites strategy with keyhole limpet hemocyanin-conjugated peptides derived from the C5aR, either alone (designated as C5aR-P1 [aa 1–21] and C5aR-P2 [aa 19–31]) or in combination (designated as C5aR-P1+C5aR-P2). Mice were fed a high-fat diet for 10 weeks. Lesions were evaluated histologically; local and systemic immune responses were analyzed by immunohistochemistry of aorta samples and cytokine measurements in plasma samples and splenocyte supernatants. Immunization of
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J mice with these peptides elicited high concentrations of antibodies against each peptide. Immunization with the single peptide inhibited plaque development. Combined inoculation with C5aR-P1+C5aR-P2 had an additive effect on reducing the lesion in the aorta sinus and descending aortas when compared with controls. This effect correlated with cellular infiltration and cytokine/chemokine secretion in the serum or in stimulated spleen cells as well as specific cellular immune responses when compared with controls.
Conclusion—
Immunization of mice with C5aR-P1 and C5aR-P2, either alone or in combination, was effective in reducing early atherosclerotic lesion development. The combined peptide is more potential than either epitope alone to reduce atherosclerotic lesion formation through the induction of a specific Treg cell response as well as blockage of monocyte differentiation into macrophages.
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Affiliation(s)
- Xinjie Lu
- From the Mary and Garry Weston Molecular Immunology Laboratory, Thrombosis Research Institute, London, UK (X.L., M.X., D.C., V.V.K.); Department of Medical Microbiology and Immunobiology, University of Szeged, Szeged, Hungary (V.E., I.F.); Virology, National Center for Epidemiology, Budapest, Hungary (E.G.); MRC Centre for Transplantation, King’s College London, London, UK (D.C.); and the Thrombosis Research Institute, Bangalore, India (L.M., V.V.K.)
| | - Min Xia
- From the Mary and Garry Weston Molecular Immunology Laboratory, Thrombosis Research Institute, London, UK (X.L., M.X., D.C., V.V.K.); Department of Medical Microbiology and Immunobiology, University of Szeged, Szeged, Hungary (V.E., I.F.); Virology, National Center for Epidemiology, Budapest, Hungary (E.G.); MRC Centre for Transplantation, King’s College London, London, UK (D.C.); and the Thrombosis Research Institute, Bangalore, India (L.M., V.V.K.)
| | - Valeria Endresz
- From the Mary and Garry Weston Molecular Immunology Laboratory, Thrombosis Research Institute, London, UK (X.L., M.X., D.C., V.V.K.); Department of Medical Microbiology and Immunobiology, University of Szeged, Szeged, Hungary (V.E., I.F.); Virology, National Center for Epidemiology, Budapest, Hungary (E.G.); MRC Centre for Transplantation, King’s College London, London, UK (D.C.); and the Thrombosis Research Institute, Bangalore, India (L.M., V.V.K.)
| | - Ildiko Faludi
- From the Mary and Garry Weston Molecular Immunology Laboratory, Thrombosis Research Institute, London, UK (X.L., M.X., D.C., V.V.K.); Department of Medical Microbiology and Immunobiology, University of Szeged, Szeged, Hungary (V.E., I.F.); Virology, National Center for Epidemiology, Budapest, Hungary (E.G.); MRC Centre for Transplantation, King’s College London, London, UK (D.C.); and the Thrombosis Research Institute, Bangalore, India (L.M., V.V.K.)
| | - Lakshmi Mundkur
- From the Mary and Garry Weston Molecular Immunology Laboratory, Thrombosis Research Institute, London, UK (X.L., M.X., D.C., V.V.K.); Department of Medical Microbiology and Immunobiology, University of Szeged, Szeged, Hungary (V.E., I.F.); Virology, National Center for Epidemiology, Budapest, Hungary (E.G.); MRC Centre for Transplantation, King’s College London, London, UK (D.C.); and the Thrombosis Research Institute, Bangalore, India (L.M., V.V.K.)
| | - Eva Gonczol
- From the Mary and Garry Weston Molecular Immunology Laboratory, Thrombosis Research Institute, London, UK (X.L., M.X., D.C., V.V.K.); Department of Medical Microbiology and Immunobiology, University of Szeged, Szeged, Hungary (V.E., I.F.); Virology, National Center for Epidemiology, Budapest, Hungary (E.G.); MRC Centre for Transplantation, King’s College London, London, UK (D.C.); and the Thrombosis Research Institute, Bangalore, India (L.M., V.V.K.)
| | - Daxin Chen
- From the Mary and Garry Weston Molecular Immunology Laboratory, Thrombosis Research Institute, London, UK (X.L., M.X., D.C., V.V.K.); Department of Medical Microbiology and Immunobiology, University of Szeged, Szeged, Hungary (V.E., I.F.); Virology, National Center for Epidemiology, Budapest, Hungary (E.G.); MRC Centre for Transplantation, King’s College London, London, UK (D.C.); and the Thrombosis Research Institute, Bangalore, India (L.M., V.V.K.)
| | - Vijay V. Kakkar
- From the Mary and Garry Weston Molecular Immunology Laboratory, Thrombosis Research Institute, London, UK (X.L., M.X., D.C., V.V.K.); Department of Medical Microbiology and Immunobiology, University of Szeged, Szeged, Hungary (V.E., I.F.); Virology, National Center for Epidemiology, Budapest, Hungary (E.G.); MRC Centre for Transplantation, King’s College London, London, UK (D.C.); and the Thrombosis Research Institute, Bangalore, India (L.M., V.V.K.)
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Nikiforovich GV, Baranski TJ. Structural mechanisms of constitutive activation in the C5a receptors with mutations in the extracellular loops: molecular modeling study. Proteins 2011; 80:71-80. [PMID: 21960464 DOI: 10.1002/prot.23162] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Revised: 07/26/2011] [Accepted: 08/19/2011] [Indexed: 12/28/2022]
Abstract
Previously we demonstrated by random saturation mutagenesis a set of mutations in the extracellular (EC) loops that constitutively activate the C5a receptor (C5aR) (Klco et al., Nat Struct Mol Biol 2005;12:320-326; Klco et al., J Biol Chem 2006;281:12010-12019). In this study, molecular modeling revealed possible conformations for the extracellular loops of the C5a receptors with mutations in the EC2 loop or in the EC3 loop. Comparison of low-energy conformations of the EC loops defined two distinct clusters of conformations typical either for strongly constitutively active mutants of C5aR (the CAM cluster) or for nonconstitutively active mutants (the non-CAM cluster). In the CAM cluster, the EC3 loop was turned towards the transmembrane (TM) helical bundle and more closely interacted with EC2 than in the non-CAM cluster. This suggested a structural mechanism of constitutive activity where EC3 contacts EC2 leading to EC2 interactions with helix TM3, thus triggering movement of TM7 towards TM2 and TM3. The movement initiates rearrangement of the system of hydrogen bonds between TM2, TM3 and TM7 including formation of the hydrogen bond between the side chains of D82(2.50) in TM2 and N296(7.49) in TM7, which is crucial for formation of the activated states of the C5a receptors (Nikiforovich et al., Proteins: Struct Funct Gene 2011;79:787-802). Since the relative large length of EC3 in C5aR (13 residues) is comparable with those in many other members of rhodopsin family of GPCRs (13-19 residues), our findings might reflect general mechanisms of receptor constitutive activation. The very recent X-ray structure of the agonist-induced constitutively active mutant of rhodopsin (Standfuss et al., Nature 2011;471:656-660) is discussed in view of our modeling results.
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