title: A single point mutation controls the cholesterol dependence of Semliki Forest virus entry and exit.
abstract: Membrane fusion and budding are key steps in the life cycle of all enveloped viruses. Semliki Forest virus (SFV) is an enveloped alphavirus that requires cellular membrane cholesterol for both membrane fusion and efficient exit of progeny virus from infected cells. We selected an SFV mutant, srf-3, that was strikingly independent of cholesterol for growth. This phenotype was conferred by a single amino acid change in the E1 spike protein subunit, proline 226 to serine, that increased the cholesterol independence of both srf-3 fusion and exit. The srf-3 mutant emphasizes the relationship between the role of cholesterol in membrane fusion and virus exit, and most significantly, identifies a novel spike protein region involved in the virus cholesterol requirement.
authors.affiliation: Department of Cell Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
authors.forename: M
authors.initials: M
authors.lastname: Vashishtha
authors.forename: T
authors.initials: T
authors.lastname: Phalen
authors.forename: M T
authors.initials: MT
authors.lastname: Marquardt
authors.forename: J S
authors.initials: JS
authors.lastname: Ryu
authors.forename: A C
authors.initials: AC
authors.lastname: Ng
authors.forename: M
authors.initials: M
authors.lastname: Kielian
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002784:Cholesterol / Q000378:metabolism*; D006224:Cricetinae; D008561:Membrane Fusion / Q000502:physiology*; D008969:Molecular Sequence Data; D017354:Point Mutation; D011392:Proline; D012672:Semliki forest virus / Q000235:genetics / Q000502:physiology*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012694:Serine; D014759:Viral Envelope Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014779:Virus Replication
chemical_list: D014759:Viral Envelope Proteins; D012694:Serine; D002784:Cholesterol; D011392:Proline