The 3' Untranslated Region of a Plant Viral RNA Directs Efficient Cap-Independent Translation in Plant and Mammalian Systems

Biblio

Publication Type:

Journal Article

Source:

Pathogens, Volume 8, Issue 1 (2019)

URL:

https://www.mdpi.com/2076-0817/8/1/28

Keywords:

3' untranslated region, 5' cap, cap-independent translation, plant virus, pseudoknot, RNA binding protein, Tombusviridae, translation initiation

Abstract:

<p>Abstract:Many plant viral RNA genomes lack a 50 cap, and instead are translated via a cap-independent<br />
translation element (CITE) in the 30 untranslated region (UTR). The panicum mosaic virus-like CITE<br />
(PTE), found in many plant viral RNAs, binds and requires the cap-binding translation initiation<br />
factor eIF4E to facilitate translation. eIF4E is structurally conserved between plants and animals,<br />
so we tested cap-independent translation efficiency of PTEs of nine plant viruses in plant and<br />
mammalian systems. The PTE from thin paspalum asymptomatic virus (TPAV) facilitated efficient<br />
cap-independent translation in wheat germ extract, rabbit reticulocyte lysate, HeLa cell lysate, and<br />
in oat and mammalian (BHK) cells. Human eIF4E bound the TPAV PTE but not a PTE that did not<br />
stimulate cap-independent translation in mammalian extracts or cells. Selective 20-hydroxyl acylation<br />
analyzed by primer extension (SHAPE) footprinting revealed that both human and wheat eIF4E<br />
protected the conserved guanosine (G)-rich domain in the TPAV PTE pseudoknot. The central G plays<br />
a key role, as it was found to be required for translation and protection from SHAPE modification<br />
by eIF4E. These results provide insight on how plant viruses gain access to the host’s translational<br />
machinery, an essential step in infection, and raise the possibility that similar PTE-like mechanisms<br />
may exist in mRNAs of mammals or their viruses.</p>

Model for cap-independent translation via the PTE sequence in the 3' UTR