Noller Harry F, Hoang Lee, Fredrick Kurt
Department of Molecular, Cell and Developmental Biology, Center for Molecular Biology of RNA, University of California at Santa Cruz, CA 95064, USA.
FEBS Lett. 2005 Feb 7;579(4):855-8. doi: 10.1016/j.febslet.2004.11.026.
The 30S ribosomal P site serves several functions in translation. It must specifically bind initiator tRNA during formation of the 30S initiation complex; bind the anticodon stem-loop of peptidyl-tRNA during the elongation phase; and help to maintain the translational reading frame when the A site is unoccupied. Early experiments provided evidence that 16S rRNA was an important component of the 30S P site. Footprinting and crosslinking studies later implicated specific nucleotides in interactions with tRNA. The crystal structures of the 30S subunit and 70S ribosome-tRNA complexes confirmed the interactions between 16S rRNA and tRNA, but also revealed contacts between tRNA and the C-terminal tails of proteins S9 and S13. Deletion of these tails now shows that the 16S rRNA contacts alone are sufficient to support protein synthesis in living cells.
30S核糖体P位点在翻译过程中发挥多种功能。在30S起始复合物形成过程中，它必须特异性结合起始tRNA；在延伸阶段结合肽基-tRNA的反密码子茎环；当A位点未被占据时，帮助维持翻译阅读框。早期实验提供了证据，表明16S rRNA是30S P位点的重要组成部分。足迹法和交联研究后来表明特定核苷酸参与与tRNA的相互作用。30S亚基和70S核糖体-tRNA复合物的晶体结构证实了16S rRNA与tRNA之间的相互作用，但也揭示了tRNA与蛋白质S9和S13的C末端尾巴之间的接触。现在缺失这些尾巴表明仅16S rRNA的接触就足以支持活细胞中的蛋白质合成。
