Department of Chemistry, Wayne State University, Detroit, MI 48202, USA.
ACS Chem Biol. 2012 May 18;7(5):871-8. doi: 10.1021/cb200497q. Epub 2012 Feb 24.
As part of the central core domain of the ribosome, helix 69 of 23S rRNA participates in an important intersubunit bridge and contacts several protein translation factors. Helix 69 is believed to play key roles in protein synthesis. Even though high-resolution crystal structures of the ribosome exist, the solution dynamics and roles of individual nucleotides in H69 are still not well-defined. To better understand the influence of modified nucleotides, specifically pseudouridine, on the multiple conformational states of helix 69 in the context of 50S subunits and 70S ribosomes, chemical probing analyses were performed on wild-type and pseudouridine-deficient bacterial ribosomes. Local structural rearrangements of helix 69 upon ribosomal subunit association and interactions with its partner, helix 44 of 16S rRNA, are observed. The helix 69 conformational states are also magnesium-dependent. The probing data presented in this study provide insight into the functional role of helix 69 dynamics and regulation of these conformational states by post-transcriptional pseudouridine modification.
作为核糖体中央核心结构域的一部分，23S rRNA 的 69 号螺旋参与了一个重要的亚基间桥接，与几个蛋白质翻译因子相互作用。69 号螺旋被认为在蛋白质合成中发挥关键作用。尽管核糖体的高分辨率晶体结构已经存在，但 H69 中单个核苷酸的溶液动力学和作用仍未得到很好的定义。为了更好地理解修饰核苷酸（特别是假尿嘧啶核苷）对 50S 亚基和 70S 核糖体中 69 号螺旋的多种构象状态的影响，对野生型和假尿嘧啶缺乏细菌核糖体进行了化学探测分析。在核糖体亚基结合和与 16S rRNA 的 44 号螺旋相互作用时，观察到 69 号螺旋的局部结构重排。69 号螺旋构象状态也依赖于镁。本研究中的探测数据提供了对 69 号螺旋动力学功能作用的深入了解，并揭示了假尿嘧啶核苷修饰对这些构象状态的调节作用。
