title: Human immunodeficiency virus type 1 matrix protein assembles on membranes as a hexamer.
abstract: The membrane-binding matrix (MA) domain of the human immunodeficiency virus type 1 (HIV-1) structural precursor Gag (PrGag) protein oligomerizes in solution as a trimer and crystallizes in three dimensions as a trimer unit. A number of models have been proposed to explain how MA trimers might align with respect to PrGag capsid (CA) N-terminal domains (NTDs), which assemble hexagonal lattices. We have examined the binding of naturally myristoylated HIV-1 matrix (MyrMA) and matrix plus capsid (MyrMACA) proteins on membranes in vitro. Unexpectedly, MyrMA and MyrMACA proteins both assembled hexagonal cage lattices on phosphatidylserine-cholesterol membranes. Membrane-bound MyrMA proteins did not organize into trimer units but, rather, organized into hexamer rings. Our results yield a model in which MA domains stack directly above NTD hexamers in immature particles, and they have implications for HIV assembly and interactions between MA and the viral membrane glycoproteins.
authors.affiliation: Vollum Institute and Department of Molecular Microbiology and Immunology, Oregon Health & Sciences University, Mail Code L220, 3181 SW Sam Jackson Park Road, Portland, OR 97201-3098, USA.
authors.forename: Ayna
authors.initials: A
authors.lastname: Alfadhli
authors.forename: Doug
authors.initials: D
authors.lastname: Huseby
authors.forename: Eliot
authors.initials: E
authors.lastname: Kapit
authors.forename: Dalbinder
authors.initials: D
authors.lastname: Colman
authors.forename: Eric
authors.initials: E
authors.lastname: Barklis
mesh_terms: D015683:Gene Products, gag / Q000737:chemistry / Q000378:metabolism; D015497:HIV-1 / Q000737:chemistry* / Q000502:physiology; D006801:Humans; D008566:Membranes / Q000378:metabolism*; D008854:Microscopy, Electron; D014763:Viral Matrix Proteins / Q000737:chemistry* / Q000378:metabolism*; D014771:Virion; D019065:Virus Assembly / Q000502:physiology*
chemical_list: D015683:Gene Products, gag; D014763:Viral Matrix Proteins