Valle Mikel, Zavialov Andrey, Sengupta Jayati, Rawat Urmila, Ehrenberg Måns, Frank Joachim
Howard Hughes Medical Institute, and Health Research Incororated at the Wadswoth Center, State University of New York, Albany, 12201, USA.
Cell. 2003 Jul 11;114(1):123-34. doi: 10.1016/s0092-8674(03)00476-8.
During the ribosomal translocation, the binding of elongation factor G (EF-G) to the pretranslocational ribosome leads to a ratchet-like rotation of the 30S subunit relative to the 50S subunit in the direction of the mRNA movement. By means of cryo-electron microscopy we observe that this rotation is accompanied by a 20 A movement of the L1 stalk of the 50S subunit, implying that this region is involved in the translocation of deacylated tRNAs from the P to the E site. These ribosomal motions can occur only when the P-site tRNA is deacylated. Prior to peptidyl-transfer to the A-site tRNA or peptide removal, the presence of the charged P-site tRNA locks the ribosome and prohibits both of these motions.
在核糖体转位过程中，延伸因子G（EF-G）与转位前核糖体的结合导致30S亚基相对于50S亚基沿mRNA移动方向发生棘轮样旋转。通过冷冻电子显微镜观察到，这种旋转伴随着50S亚基L1茎的20 Å移动，这意味着该区域参与了脱酰基tRNA从P位点到E位点的转位。这些核糖体运动只有在P位点tRNA脱酰基时才会发生。在肽基转移到A位点tRNA或肽移除之前，带电荷的P位点tRNA的存在会锁定核糖体并阻止这两种运动。
