Gag-Pol supplied in trans is efficiently packaged and supports viral function in human immunodeficiency virus type 1.
The intracellular trafficking and subsequent incorporation of Gag-Pol into human immunodeficiency virus type 1 (HIV-1) remains poorly defined. Gag-Pol is encoded by the same mRNA as Gag and is generated by ribosomal frameshifting. The multimerization of Gag and Gag-Pol is an essential step in the formation of infectious viral particles. In this study, we examined whether the interaction between Gag and Gag-Pol is initiated during protein translation in order to facilitate the trafficking and subsequent packaging of Gag-Pol into the virion. A conditional cotransfection system was developed in which virion formation required the coexpression of two HIV-1-based plasmids, one that produces both Gag and Gag-Pol and one that only produces Gag-Pol. The Gag-Pol proteins were either immunotagged with a His epitope or functionally tagged with a mutation (K65R) in reverse transcriptase that is associated with drug resistance. Gag-Pol packaging was assessed to determine whether the Gag-Pol incorporated into the virion was preferentially packaged from the plasmid that expressed both Gag and Gag-Pol or whether it could be packaged from either plasmid. Our data show that translation of Gag and Gag-Pol from the same mRNA is not critical for virion packaging of the Gag-Pol polyprotein or for viral function.
Hill
M K
MK
AIDS Pathogenesis Research Unit, Macfarlane Burnet Centre for Medical Research, Fairfield, Victoria 3078, Australia.
Hooker
C W
CW
Harrich
D
D
Crowe
S M
SM
Mak
J
J
D015685:Fusion Proteins, gag-pol / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D015683:Gene Products, gag / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D015497:HIV-1 / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D014176:Protein Biosynthesis; D012333:RNA, Messenger; D012367:RNA, Viral; D014158:Transcription, Genetic; D014162:Transfection; D019065:Virus Assembly
D015685:Fusion Proteins, gag-pol; D015683:Gene Products, gag; D012333:RNA, Messenger; D012367:RNA, Viral