title: A cis-acting element in retroviral genomic RNA links Gag-Pol ribosomal frameshifting to selective viral RNA encapsidation.
abstract: During retroviral RNA encapsidation, two full-length genomic (g) RNAs are selectively incorporated into assembling virions. Packaging involves a cis-acting packaging element (Ψ) within the 5' untranslated region of unspliced HIV-1 RNA genome. However, the mechanism(s) that selects and limits gRNAs for packaging remains uncertain. Using a dual complementation system involving bipartite HIV-1 gRNA, we observed that gRNA packaging is additionally dependent on a cis-acting RNA element, the genomic RNA packaging enhancer (GRPE), found within the gag p1-p6 domain and overlapping the Gag-Pol ribosomal frameshift signal. Deleting or disrupting the two conserved GRPE stem loops diminished gRNA packaging and infectivity >50-fold, while deleting gag sequences between Ψ and GRPE had no effect. Downregulating the translation termination factor eRF1 produces defective virus particles containing 20 times more gRNA. Thus, only the HIV-1 RNAs employed for Gag-Pol translation may be specifically selected for encapsidation, possibly explaining the limitation of two gRNAs per virion.
authors: Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, OH 44106, USA.
authors: Mastooreh
authors: M
authors: Chamanian
authors: Katarzyna J
authors: KJ
authors: Purzycka
authors: Paul T
authors: PT
authors: Wille
authors: Janice S
authors: JS
authors: Ha
authors: David
authors: D
authors: McDonald
authors: Yong
authors: Y
authors: Gao
authors: Stuart F J
authors: SF
authors: Le Grice
authors: Eric J
authors: EJ
authors: Arts
mesh_terms: D018965:Frameshifting, Ribosomal; D015685:Fusion Proteins, gag-pol / Q000235:genetics / Q000378:metabolism*; D005816:Genetic Complementation Test; D016679:Genome, Viral; D057809:HEK293 Cells; D015497:HIV-1 / Q000235:genetics* / Q000502:physiology; D006801:Humans; D055029:Inverted Repeat Sequences; D009690:Nucleic Acid Conformation; D010454:Peptide Termination Factors / Q000235:genetics / Q000378:metabolism; D014176:Protein Biosynthesis; D020871:RNA Stability; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012367:RNA, Viral / Q000235:genetics*; D038621:Regulatory Sequences, Ribonucleic Acid; D014162:Transfection; D019065:Virus Assembly
chemical_list: D015685:Fusion Proteins, gag-pol; D010454:Peptide Termination Factors; D012333:RNA, Messenger; D012367:RNA, Viral; D038621:Regulatory Sequences, Ribonucleic Acid