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Table 2 Retrovirus:host interactions involved in retroviral translation control

From: Mechanisms employed by retroviruses to exploit host factors for translational control of a complicated proteome

  Host factor Examples of interacting virusa Effect on translation
Interacts with retrovirus protein & RNA Protein kinase R (PKR) HIV-1, HTLV-1 HIV-1 Tat reduces PKR autophosphorylation. Tat and eIF2α compete as substrates of PKR. High levels of HIV-1 TAR RNA or HTLV-1 RxRE inhibit PKR autophosphorylation.
  Small RNA pathway components
(Dicer & Drosha)
PFV, HIV-1 PFV Tas and HIV-1 Tat act as RNA silencing suppressors that combat the antiviral effect of small RNA pathway. Also miRNAs may be encoded by retroviruses that downregulate host antiviral defense.
Interacts with retrovirus RNA TAR RNA binding protein (TRBP) HIV-1 Binding of TRBP to HIV-1 TAR RNA results in increased HIV-1 transcription and translation.
  2', 5'-oligoadenylate-synthetase/RNaseL HIV-1, HTLV-1 HIV-1 5' UTR RNA binds 2-5OAS resulting in RNAseL activity in vitro. HIV-1 infection is associated with reduced interferon production and reduced 2-5A:RNAseL binding, allowing HIV-1 mRNA to evade cleavage by RNaseL. HTLV-1 RxRE activates 2-5OAS in vitro.
  RNA helicase A
(RHA or DHX9)
SNV, REV-A, HTLV-1, MPMV, HFV, FeLV, BLV, HIV-1 RHA binds PCE mRNA leading to increased polysome association and efficient protein synthesis.
  9G8 MPMV In overexpression experiments, hyper-phosphorylated 9G8 binds constitutive transport element-containing reporter mRNA resulting in increased polysome accumulation and protein synthesis.
  Sam68, SLM-1, SLM-2 HIV-1, HTLV-1, EIAV, MPMV Sam68, SLM-1 and SLM-2 act synergistically with HIV-1 Rev, HTLV-1 Rex and EIAV ERev to facilitate expression and proper cytoplasmic localization of RRE-containing mRNA. Sam68 also enhances translation of mRNA containing the MPMV constitutive transport element.
  hnRNP E1 HIV-1 hnRNPE1 binds HIV-1 mRNA at the exon splicing silencer in Rev exon (ESSE) and reduces Gag, Env, and Rev protein production.
  eRF1 MLV MLV reverse transcriptase binds eRF1 promoting readthrough of the gag termination codon to produce proteins encoded by gag-pol.
  1. a BLV, bovine leukemia virus; EIAV, equine infectious anemia virus; FeLV, feline leukemia virus; HFV, human foamy virus; HTLV-1, human T-cell leukemia virus type 1; MLV, murine leukemia virus; MPMV, Mason-Pfizer monkey virus; REV-A, reticuloendotheliosis virus strain A; SNV, spleen necrosis virus.