Structural switching dynamically controls the doubly pseudoknotted Rous sarcoma virus-programmed ribosomal frameshifting element

• 成果类型: Article
• 署名作者: Jones, Christopher P.; Ferre-D'Amare, Adrian R.
• 署名单位: National Institutes of Health (NIH) - USA; NIH National Heart Lung & Blood Institute (NHLBI)
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-12468
• DOI: 10.1073/pnas.2418418122
• 发表日期: 2025-04-08
• 关键词: crystal-structure; rna pseudoknot; downstream; gene; dms

摘要

A hallmark of retrovirus replication is the translation of two different polyproteins from one RNA through programmed-1 frameshifting. This is a mechanism in which the actively translating ribosome is induced to slip in the 5 ' direction at a defined codon and then continues translating in the new reading frame. Programmed frameshifting controls the stoichiometry of viral proteins and is therefore under stringent evolutionary selection. Forty years ago, the first frameshifting stimulatory element was discovered in the Rous sarcoma virus. The similar to 120 nt RNA segment was predicted to contain a pseudo-knot, but its 3D structure has remained elusive. Now, we have determined cryoEM and X-ray crystallographic structures of this classic retroviral element, finding that it adopts a butterfly-like double-pseudoknot fold. One wing contains a dynamic pyrimidine-rich helix, observed crystallographically in two conformations and in a third conformation via cryoEM. The other wing encompasses the predicted pseudoknot, which interacts with a second unexpected pseudoknot through a toggle residue, A2546. This key purine switches conformations between structural states and tunes the stability of interacting residues in the two wings. We find that its mutation can modulate frameshifting by as much as 50-fold, likely by altering the relative abundance of different structural states in the conformational ensemble of the RNA. Taken together, our structure-function analyses reveal how a dynamic double pseudoknot junction stimulates frameshifting by taking advantage of conformational heterogeneity, supporting a multistate model in which high Shannon entropy enhances frameshifting efficiency.