TY - JOUR TI - Folding behavior of a T-shaped, ribosome-binding translation enhancer implicated in a wide-spread conformational switch AU - Le, My-Tra AU - Kasprzak, Wojciech K AU - Kim, Taejin AU - Gao, Feng AU - Young, Megan YL AU - Yuan, Xuefeng AU - Shapiro, Bruce A AU - Seog, Joonil AU - Simon, Anne E A2 - Sonenberg, Nahum VL - 6 PY - 2017 DA - 2017/02/10 SP - e22883 C1 - eLife 2017;6:e22883 DO - 10.7554/eLife.22883 UR - https://doi.org/10.7554/eLife.22883 AB - 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/Ψ3 required five upstream adenylates, and H4a/Ψ3 was necessary for cooperative association of two other hairpins (H5/H4b) in Mg2+. SMD recapitulated the TSS unfolding order in the absence of Mg2+, 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/Ψ3, leading to loss of H5/H4b interaction and promoting a conformational switch interrupting translation and promoting replication. KW - optical tweezers KW - RNA structure KW - Turnip crinkle virus KW - molecular dynamics KW - RNA virus JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -