Recruitment of 40S Ribosome to the 3′ Untranslated Region (UTR) of a Viral mRNA, via the eIF4F Complex, Facilitates Cap-independent Translation [RNA]

March 19th, 2015 by Das Sharma, S., Kraft, J. J., Miller, W. A., Goss, D. J.

Barley yellow dwarf virus (BYDV) mRNA, which lacks both cap and poly(A) tail, has a translation element (3 ′BTE) in its 3′ UTR essential for efficient translation initiation at the 5′-proximal AUG. This mechanism requires eukaryotic initiation factor 4G (eIF4G), subunit of heterodimer eIF4F (plant eeIF4F lacks eIF4A), and 3′BTE-5′ UTR interaction. Using fluorescence anisotropy, SHAPE analysis and toe printing, we found that (i) 40S subunits bind to BTE (Kd = 350± 30 nM), (ii) the helicase complex eIF4F-eIF4A-eIF4B-ATP increases 40S subunit binding (Kd = 120±10 nM) to the conserved SL-I of the 3′BTE by exposing more unpaired bases and (iii) long-distance base pairing transfers this complex to the 5′ end of the mRNA where translation initiates. While 3′-5′ interactions have been recognized as important in mRNA translation, BYDV employs a novel mechanism utilizing the 3′UTR as the primary site of ribosome recruitment.
  • Posted in Journal of Biological Chemistry, Publications
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