Sherlock Madeline E, Langeberg Conner J, Segar Katherine E, Kieft Jeffrey S
Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA.
Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA.
Cell Rep. 2025 Feb 25;44(2):115236. doi: 10.1016/j.celrep.2025.115236. Epub 2025 Feb 1.
Certain viral RNAs encode proteins downstream of their main open reading frame, expressed through "termination-reinitiation" events. In some cases, structures located upstream of the first stop codon within these viral RNAs bind the ribosome, inhibiting ribosome recycling and inducing reinitiation. We used bioinformatics methods to identify new examples of viral reinitiation-stimulating RNAs and experimentally verified their secondary structure and function. We determined the structure of a representative viral RNA-ribosome complex using cryoelectron microscopy (cryo-EM). 3D classification and variability analyses reveal that the viral RNA structure can sample a range of conformations while remaining tethered to the ribosome, enabling the ribosome to find a reinitiation start site within a limited range of mRNA sequence. Evaluating the conserved features and constraints of this entire RNA class within the context of the cryo-EM reconstruction provides insight into mechanisms enabling reinitiation, a translation regulation strategy employed by many other viral and eukaryotic systems.
某些病毒RNA在其主要开放阅读框下游编码蛋白质，通过“终止-重新起始”事件表达。在某些情况下，这些病毒RNA中第一个终止密码子上游的结构会结合核糖体，抑制核糖体循环并诱导重新起始。我们使用生物信息学方法来鉴定病毒重新起始刺激RNA的新实例，并通过实验验证了它们的二级结构和功能。我们使用冷冻电子显微镜（cryo-EM）确定了代表性病毒RNA-核糖体复合物的结构。三维分类和变异性分析表明，病毒RNA结构可以在保持与核糖体相连的同时采样一系列构象，使核糖体能够在有限的mRNA序列范围内找到重新起始的起始位点。在冷冻电子显微镜重建的背景下评估这一整个RNA类别的保守特征和限制，有助于深入了解实现重新起始的机制，这是许多其他病毒和真核系统采用的一种翻译调控策略。
