Identification of the HIV-1 NC binding interface in Alix Bro1 reveals a role for RNA.
HIV-1 recruits members of ESCRT, the cell membrane fission machinery that promotes virus exit. HIV-1 Gag protein gains access to ESCRT directly by binding Alix, an ESCRT-associated protein that promotes budding. The Alix Bro1 and V domains bind Gag NC and p6 regions, respectively. Whereas V-p6 binding and function are well characterized, residues in Bro1 that interact with NC and their functional contribution to Alix-mediated HIV-1 budding are unknown. We mapped Bro1 residues that constitute the NC binding interface and found that they are critical for function. Intriguingly, residues involved in interactions on both sides of the Bro1-NC interface are positively charged, suggesting the involvement of a negatively charged cellular factor serving as a bridge. Nuclease treatment eliminated Bro1-NC interactions, revealing the involvement of RNA. These findings establish a direct role for NC in mediating interactions with ESCRT necessary for virus release and report the first evidence of RNA involvement in such recruitments.
Viral Budding Unit, Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA.
Paola
P
Sette
Vincent
V
Dussupt
Fadila
F
Bouamr
D001665:Binding Sites; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D056827:Endosomal Sorting Complexes Required for Transport / Q000235:genetics / Q000378:metabolism*; D015497:HIV-1 / Q000502:physiology; D054884:Host-Pathogen Interactions; D006801:Humans; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D012367:RNA, Viral / Q000378:metabolism*; D057074:Virus Release; D054301:gag Gene Products, Human Immunodeficiency Virus / Q000378:metabolism*
D002135:Calcium-Binding Proteins; D018797:Cell Cycle Proteins; D056827:Endosomal Sorting Complexes Required for Transport; C071884:NCP7 protein, Human immunodeficiency virus 1; C117020:PDCD6IP protein, human; D012367:RNA, Viral; D054301:gag Gene Products, Human Immunodeficiency Virus