title: Biochemical reconstitution of hemorrhagic-fever arenavirus envelope glycoprotein-mediated membrane fusion.
abstract: The membrane-anchored proteins of enveloped viruses form labile spikes on the virion surface, primed to undergo large-scale conformational changes culminating in virus-cell membrane fusion and viral entry. The prefusion form of these envelope glycoproteins thus represents an important molecular target for antiviral intervention. A critical roadblock to this endeavor has been our inability to produce the prefusion envelope glycoprotein trimer for biochemical and structural analysis. Through our studies of the GPC envelope glycoprotein of the hemorrhagic fever arenaviruses, we have shown that GPC is unique among class I viral fusion proteins in that the mature complex retains a stable signal peptide (SSP) in addition to the conventional receptor-binding and transmembrane fusion subunits. In this report we show that the recombinant GPC precursor can be produced as a discrete native-like trimer and that its proteolytic cleavage generates the mature glycoprotein. Proteoliposomes containing the cleaved GPC mediate pH-dependent membrane fusion, a characteristic feature of arenavirus entry. This reaction is inhibited by arenavirus-specific monoclonal antibodies and small-molecule fusion inhibitors. The in vitro reconstitution of GPC-mediated membrane-fusion activity offers unprecedented opportunities for biochemical and structural studies of arenavirus entry and its inhibition. To our knowledge, this report is the first to demonstrate functional reconstitution of membrane fusion by a viral envelope glycoprotein.
authors.affiliation: Center for Biomolecular Structure and Dynamics, The University of Montana, Missoula, MT, USA.
authors.forename: Celestine J
authors.initials: CJ
authors.lastname: Thomas
authors.forename: Sundaresh
authors.initials: S
authors.lastname: Shankar
authors.forename: Hedi E
authors.initials: HE
authors.lastname: Casquilho-Gray
authors.forename: Joanne
authors.initials: J
authors.lastname: York
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Sprang
authors.forename: Jack H
authors.initials: JH
authors.lastname: Nunberg
mesh_terms: D000818:Animals; D057134:Antibodies, Neutralizing / Q000276:immunology; D002522:Chlorocebus aethiops; D045683:Furin / Q000378:metabolism; D006023:Glycoproteins / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D018051:Junin virus / Q000378:metabolism*; D008055:Lipids / Q000737:chemistry; D008561:Membrane Fusion; D050505:Mutant Proteins / Q000378:metabolism; D009500:Neutralization Tests; D011487:Protein Conformation; D011510:Proteolipids / Q000378:metabolism; D059748:Proteolysis; D011994:Recombinant Proteins / Q000378:metabolism; D020349:Surface Plasmon Resonance; D014709:Vero Cells; D014759:Viral Envelope Proteins / Q000378:metabolism*; D017201:Virus Shedding
chemical_list: D057134:Antibodies, Neutralizing; D006023:Glycoproteins; D008055:Lipids; D050505:Mutant Proteins; D011510:Proteolipids; D011994:Recombinant Proteins; D014759:Viral Envelope Proteins; C020485:proteoliposomes; D045683:Furin