title: Human immunodeficiency virus type 1 Gag engages the Bro1 domain of ALIX/AIP1 through the nucleocapsid.
abstract: Human immunodeficiency virus type 1 (HIV-1) and other retroviruses harbor short peptide motifs in Gag that promote the release of infectious virions. These motifs, known as late assembly (L) domains, recruit a cellular budding machinery that is required for the formation of multivesicular bodies (MVBs). The primary L domain of HIV-1 maps to a PTAP motif in the p6 region of Gag and engages the MVB pathway by binding to Tsg101. Additionally, HIV-1 p6 harbors an auxiliary L domain that binds to the V domain of ALIX, another component of the MVB pathway. We now show that ALIX also binds to the nucleocapsid (NC) domain of HIV-1 Gag and that ALIX and its isolated Bro1 domain can be specifically packaged into viral particles via NC. The interaction with ALIX depended on the zinc fingers of NC, which mediate the specific packaging of genomic viral RNA, but was not disrupted by nuclease treatment. We also observed that HIV-1 zinc finger mutants were defective for particle production and exhibited a similar defect in Gag processing as a PTAP deletion mutant. The effects of the zinc finger and PTAP mutations were not additive, suggesting a functional relationship between NC and p6. However, in contrast to the PTAP deletion mutant, the double mutants could not be rescued by overexpressing ALIX, further supporting the notion that NC plays a role in virus release.
authors.affiliation: UMass Medical School, LRB 526, 364 Plantation Street, Worcester, MA 01605, USA.
authors.forename: Sergei
authors.initials: S
authors.lastname: Popov
authors.forename: Elena
authors.initials: E
authors.lastname: Popova
authors.forename: Michio
authors.initials: M
authors.lastname: Inoue
authors.forename: Heinrich G
authors.initials: HG
authors.lastname: Göttlinger
mesh_terms: D002135:Calcium-Binding Proteins / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000378:metabolism*; D056827:Endosomal Sorting Complexes Required for Transport; D015497:HIV-1 / Q000502:physiology*; D011485:Protein Binding; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D054301:gag Gene Products, Human Immunodeficiency Virus / Q000235:genetics / Q000378:metabolism*
chemical_list: D002135:Calcium-Binding Proteins; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D056827:Endosomal Sorting Complexes Required for Transport; C071884:NCP7 protein, Human immunodeficiency virus 1; C117020:PDCD6IP protein, human; D054301:gag Gene Products, Human Immunodeficiency Virus; C083002:p6 gag protein, Human immunodeficiency virus 1