title: Homodimeric association of the spike glycoproteins G1 and G2 of Uukuniemi virus.
abstract: We have studied the interactions of the G1 and G2 membrane glycoproteins of Uukuniemi virus, a bunyavirus, in virus particles and in Triton X-100-solubilized virus. The G1 glycoprotein in intact virus or in Triton solution could be oxidized into a covalent homodimer using Cu2+ ion as a catalyst. Immunoprecipitations of the glycoproteins from Triton-solubilized virus lysates showed that G1 and G2 do not form a stable heterodimeric or heterooligomeric complex. The oligomeric association of G1 and G2 was further analyzed using centrifugation in sucrose gradients in the presence of Triton X-100. The results indicate that G1 exists as a Triton-resistant pH-insensitive homodimer. This is in contrast to the behavior of G2, which exists as a homodimer and partially as a monomer at pH 6.4 or above and is dissociated completely into a monomer at pH 6.0 or below. The threshold for the dimer-monomer shift of G2 is between pH 6.2 and pH 6.0. Electron microscopy studies show that the surface structure of the virus particle undergoes a pH-dependent change. Studies on the kinetics of virus entry suggest that pH below 6.2 is necessary for the penetration of Uukuniemi virus.
authors.affiliation: Department of Biosciences, University of Helsinki, Finland.
authors.forename: H
authors.initials: H
authors.lastname: Rönkä
authors.forename: P
authors.initials: P
authors.lastname: Hildén
authors.forename: C H
authors.initials: CH
authors.lastname: Von Bonsdorff
authors.forename: E
authors.initials: E
authors.lastname: Kuismanen
mesh_terms: D000818:Animals; D002460:Cell Line; D002478:Cells, Cultured; D002499:Centrifugation, Density Gradient; D002642:Chick Embryo; D003300:Copper / Q000494:pharmacology; D006224:Cricetinae; D005347:Fibroblasts; D007668:Kidney; D046911:Macromolecular Substances; D008715:Methionine / Q000378:metabolism; D008854:Microscopy, Electron; D008970:Molecular Weight; D017830:Octoxynol; D010084:Oxidation-Reduction; D012995:Solubility; D013462:Sulfur Radioisotopes; D018066:Uukuniemi virus / Q000254:growth & development / Q000378:metabolism* / Q000648:ultrastructure; D014759:Viral Envelope Proteins / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D046911:Macromolecular Substances; D013462:Sulfur Radioisotopes; D014759:Viral Envelope Proteins; D003300:Copper; D017830:Octoxynol; D008715:Methionine