Folding behavior of a T-shaped, ribosome-binding translation enhancer implicated in a wide-spread conformational switch.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 28186489.
- Also identified by DOI 10.7554/eLife.22883 and PMC identifier 5336357.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Turnip crinkle virus contains a T-shaped, ribosome-binding, translation enhancer (TSS) in its 3'UTR that serves as a hub for interactions throughout the region. The viral RNA-dependent RNA polymerase (RdRp) causes the TSS/surrounding region to undergo a conformational shift postulated to inhibit translation. Using optical tweezers (OT) and steered molecular dynamic simulations (SMD), we found that the unusual stability of pseudoknotted element H4a/Ψ<sub>3</sub> required five upstream adenylates, and H4a/Ψ<sub>3</sub> was necessary for cooperative association of two other hairpins (H5/H4b) in Mg<sup>2+</sup>. SMD recapitulated the TSS unfolding order in the absence of Mg<sup>2+</sup>, showed dependence of the resistance to pulling on the 3D orientation and gave structural insights into the measured contour lengths of the TSS structure elements. Adenylate mutations eliminated one-site RdRp binding to the 3'UTR, suggesting that RdRp binding to the adenylates disrupts H4a/Ψ<sub>3</sub>, leading to loss of H5/H4b interaction and promoting a conformational switch interrupting translation and promoting replication.
Medical subject headings
- Carmovirus
- Nucleic Acid Conformation
- Protein Biosynthesis
- RNA, Viral
- RNA-Dependent RNA Polymerase
- Ribosomes