Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa 50011, United States.
Cryo-EM Facility, Iowa State University, Ames, Iowa 50011, United States.
Biochemistry. 2024 May 21;63(10):1287-1296. doi: 10.1021/acs.biochem.3c00716. Epub 2024 May 10.
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) frameshift stimulatory element (FSE) is necessary for programmed -1 ribosomal frameshifting (-1 PRF) and optimized viral efficacy. The FSE has an abundance of context-dependent alternate conformations, but two of the structures most crucial to -1 PRF are an attenuator hairpin and a three-stem H-type pseudoknot structure. A crystal structure of the pseudoknot alone features three RNA stems in a helically stacked linear structure, whereas a 6.9 Å cryo-EM structure including the upstream heptameric slippery site resulted in a bend between two stems. Our previous research alluded to an extended upstream multibranch loop that includes both the attenuator hairpin and the slippery site-a conformation not previously modeled. We aim to provide further context to the SARS-CoV-2 FSE via computational and medium resolution cryo-EM approaches, by presenting a 6.1 Å cryo-EM structure featuring a linear pseudoknot structure and a dynamic upstream multibranch loop.
严重急性呼吸综合征冠状病毒 2（SARS-CoV-2）框架移位刺激元件（FSE）是程序性-1 核糖体移码（-1 PRF）和优化病毒功效所必需的。FSE 具有丰富的上下文相关的替代构象，但对-1 PRF 最重要的两种结构是衰减子发夹和三茎 H 型假结结构。单独的假结晶体结构具有三个在螺旋堆叠线性结构中的 RNA 茎，而包括上游七聚体滑链位点的 6.9 Å 冷冻电镜结构导致两个茎之间的弯曲。我们之前的研究暗示了一个扩展的上游多分支环，其中包括衰减子发夹和滑链位点——一种以前未建模的构象。我们旨在通过提供具有线性假结结构和动态上游多分支环的 6.1 Å 冷冻电镜结构，通过计算和中等分辨率的冷冻电镜方法，为 SARS-CoV-2 FSE 提供更多的背景信息。
