title: Retrovirus capsid protein assembly arrangements.
abstract: During retrovirus particle assembly and morphogenesis, the retrovirus structural (Gag) proteins organize into two different arrangements: an immature form assembled by precursor Gag (PrGag) proteins; and a mature form, composed of proteins processed from PrGag. Central to both Gag protein arrangements is the capsid (CA) protein, a domain of PrGag, which is cleaved from the precursor to yield a mature Gag protein composed of an N-terminal domain (NTD), a flexible linker region, and a C-terminal domain (CTD). Because Gag interactions have proven difficult to examine in virions, a number of investigations have focused on the analysis of structures assembled in vitro. We have used electron microscope (EM) image reconstruction techniques to examine assembly products formed by two different CA variants of both human immunodeficiency virus type 1 (HIV-1) and the Moloney murine leukemia virus (M-MuLV). Interestingly, two types of hexameric protein arrangements were observed for each virus type. One organizational scheme featured hexamers composed of putative NTD dimer subunits, with sharing of subunits between neighbor hexamers. The second arrangement used apparent NTD monomers to coordinate hexamers, involved no subunit sharing, and employed putative CTD interactions to connect hexamers. Conversion between the two assembly forms may be achieved by making or breaking the proposed symmetric NTD dimer contacts in a process that appears to mimic viral morphogenesis.
authors.affiliation: Vollum Institute and Department of Microbiology MC L220, Oregon Health and Science University, 31814 SW Sam Jackson Park Rd, Portland, OR 97201-3098, USA.
authors.forename: Keith
authors.initials: K
authors.lastname: Mayo
authors.forename: Doug
authors.initials: D
authors.lastname: Huseby
authors.forename: Jason
authors.initials: J
authors.lastname: McDermott
authors.forename: Brian
authors.initials: B
authors.lastname: Arvidson
authors.forename: Liam
authors.initials: L
authors.lastname: Finlay
authors.forename: Eric
authors.initials: E
authors.lastname: Barklis
mesh_terms: D000595:Amino Acid Sequence; D036022:Capsid Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D018360:Crystallography, X-Ray; D019281:Dimerization; D015497:HIV-1 / Q000737:chemistry / Q000254:growth & development; D021621:Imaging, Three-Dimensional; D008854:Microscopy, Electron; D008958:Models, Molecular; D008969:Molecular Sequence Data; D008979:Moloney murine leukemia virus / Q000737:chemistry; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D021122:Protein Subunits; D012190:Retroviridae / Q000737:chemistry* / Q000254:growth & development; D055672:Static Electricity; D019065:Virus Assembly
chemical_list: D036022:Capsid Proteins; D021122:Protein Subunits