title: Heterodimerization of the two major envelope proteins is essential for arterivirus infectivity.
abstract: The two major envelope proteins of arteriviruses, the membrane protein (M) and the major glycoprotein (GP(5)), associate into a disulfide-linked heterodimer that is incorporated into the virion and has been assumed to be a prerequisite for virus assembly. Using an equine arteritis virus (EAV) infectious cDNA clone, we have analyzed the requirement for GP(5)-M heterodimerization and have identified the Cys residues involved in the formation of the GP(5)-M disulfide bond. The single Cys residue (Cys-8) in the M ectodomain was crucial for heterodimerization and virus infectivity. Mutagenesis of any of the five Cys residues in the GP(5) ectodomain or removal of the single GP(5) N-glycosylation site also rendered the full-length clone noninfectious. However, an analysis of revertants yielded an exceptional pseudorevertant in which residues 52 to 79 of the GP(5) ectodomain had been deleted and the original Cys-80-->Ser mutation had been maintained. Consequently, this revertant lacked the GP(5) N-glycosyation site (Asn-56) and retained only a single cysteine residue (Cys-34). By using this GP(5) deletion, we confirmed that Cys-34 of GP(5) and Cys-8 of M are essential for GP(5)-M heterodimerization, a key event in the assembly of the EAV envelope.
authors.affiliation: Molecular Virology Laboratory, Department of Medical Microbiology, Center of Infectious Diseases, Leiden University Medical Center, The Netherlands. E.J.Snijder@LUMC.nl
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Snijder
authors.forename: Jessika C
authors.initials: JC
authors.lastname: Dobbe
authors.forename: Willy J M
authors.initials: WJ
authors.lastname: Spaan
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019281:Dimerization; D007240:Equartevirus / Q000737:chemistry* / Q000472:pathogenicity*; D006031:Glycosylation; D006056:Golgi Apparatus / Q000821:virology; D008562:Membrane Glycoproteins / Q000737:chemistry; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D013329:Structure-Activity Relationship; D014759:Viral Envelope Proteins / Q000737:chemistry* / Q000502:physiology; D014763:Viral Matrix Proteins / Q000737:chemistry* / Q000502:physiology
chemical_list: D008562:Membrane Glycoproteins; D014759:Viral Envelope Proteins; D014763:Viral Matrix Proteins