Ofverstedt L G, Zhang K, Tapio S, Skoglund U, Isaksson L A
Department of Cell and Molecular Biology, Medical Nobel Institute, Karolinska Institute, Stockholm, Sweden.
Cell. 1994 Nov 18;79(4):629-38. doi: 10.1016/0092-8674(94)90548-7.
Structures in situ of individual ribosomes in E. coli have been determined by computer-aided electron microscope tomography using a tilt series of positively stained embedded cellular sections. Amino acid starvation of a bacterial culture, causing a deficiency for aminoacyl-tRNA, induces a spatial separation between the ribosomal subunits compared with ribosomes in exponentially growing cells. Eight ribosomes from each growth condition were aligned to each other, and the two average structures were determined. Comparison of these suggests that the distance between the two subunits increases by approximately 3 nm upon starvation for aminoacyl-tRNA during protein synthesis. Ribosomes in most other states of the translational elongation cycle in exponentially growing cells show a more compact structure than previously realized.
通过使用一系列倾斜的正染色包埋细胞切片的计算机辅助电子显微镜断层扫描技术，已确定了大肠杆菌中单个核糖体的原位结构。细菌培养物的氨基酸饥饿会导致氨酰 - tRNA缺乏，与指数生长细胞中的核糖体相比，会诱导核糖体亚基之间的空间分离。将每种生长条件下的八个核糖体相互对齐，并确定了两个平均结构。这些结构的比较表明，在蛋白质合成过程中，氨酰 - tRNA饥饿时两个亚基之间的距离增加约3纳米。指数生长细胞中翻译延伸循环的大多数其他状态下的核糖体显示出比以前认识到的更紧密的结构。
