VanLoock M S, Agrawal R K, Gabashvili I S, Qi L, Frank J, Harvey S C
Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL 35294-0005, USA.
J Mol Biol. 2000 Dec 8;304(4):507-15. doi: 10.1006/jmbi.2000.4213.
The ribosome undergoes pronounced periodic conformational changes during protein synthesis. Of particular importance are those occurring around the decoding site, the region of the 16 S rRNA interacting with the mRNA-(tRNA)(2) complex. We have incorporated structural information from X-ray crystallography and nuclear magnetic resonance into cryo-electron microscopic maps of ribosomal complexes designed to capture structural changes at the translocation step of the polypeptide elongation cycle. The A-site region of the decoding site actively participates in the translocation of the tRNA from the A to the P-site upon GTP hydrolysis by elongation factor G, shifting approximately 8 A toward the P-site. This implies that elongation factor G actively pushes both the decoding site and the mRNA/tRNA complex during translocation.
核糖体在蛋白质合成过程中会发生显著的周期性构象变化。特别重要的是那些发生在解码位点周围的变化，即16 S rRNA与mRNA-(tRNA)₂复合物相互作用的区域。我们已将X射线晶体学和核磁共振的结构信息整合到核糖体复合物的冷冻电子显微镜图谱中，这些图谱旨在捕捉多肽延伸循环转位步骤中的结构变化。解码位点的A位点区域在延伸因子G水解GTP后，积极参与tRNA从A位点到P位点的转位，向P位点方向移动约8埃。这意味着延伸因子G在转位过程中积极推动解码位点以及mRNA/tRNA复合物。
