title: Palmitoylation of the murine leukemia virus envelope protein is critical for lipid raft association and surface expression.
abstract: To investigate the association of the murine leukemia virus (MuLV) Env protein with lipid rafts, we compared wild-type and palmitoylation-deficient mutant Env proteins by using extraction with the mild detergent Triton X-100 (TX-100) followed by a sucrose gradient flotation assay. We found that the wild-type MuLV Env protein was resistant to ice-cold TX-100 treatment and floated to the top of the gradients. In contrast, we observed that the palmitoylation-deficient mutant Env protein was mostly soluble when extracted by ice-cold TX-100 and stayed at the bottom of the gradients. Both the wild-type and mutant Env proteins were found to be soluble when treated with methyl-beta-cyclodextrin before extraction with ice-cold TX-100 or when treated with ice-cold octyl-beta-glucoside instead of TX-100. These results indicate that the MuLV Env protein is associated with lipid rafts and that palmitoylation of the Env protein is critical for lipid raft association. Although the palmitoylation-deficient Env mutant was synthesized at a level similar to that of the wild-type Env, it was found to be expressed at reduced levels on the cell surface. We observed syncytium formation activity with both the wild-type and mutant Env proteins, indicating that palmitoylation or raft association is not required for MuLV viral fusion activity.
authors.affiliation: Department of Microbiology and Immunology and Emory Vaccine Center, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
authors.forename: Min
authors.initials: M
authors.lastname: Li
authors.forename: Chinglai
authors.initials: C
authors.lastname: Yang
authors.forename: Suxiang
authors.initials: S
authors.lastname: Tong
authors.forename: Armin
authors.initials: A
authors.lastname: Weidmann
authors.forename: Richard W
authors.initials: RW
authors.lastname: Compans
mesh_terms: D016475:3T3 Cells; D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism / Q000821:virology; D015726:Giant Cells / Q000473:pathology / Q000821:virology; D009052:Leukemia Virus, Murine / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D008561:Membrane Fusion; D021962:Membrane Microdomains / Q000378:metabolism*; D051379:Mice; D009154:Mutation; D017830:Octoxynol; D019308:Palmitic Acid / Q000378:metabolism*; D012995:Solubility; D014759:Viral Envelope Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D014759:Viral Envelope Proteins; D019308:Palmitic Acid; D017830:Octoxynol