Gabashvili I S, Agrawal R K, Grassucci R, Squires C L, Dahlberg A E, Frank J
The Wadsworth Center, State University of New York at Albany, 12201-0509, USA.
EMBO J. 1999 Nov 15;18(22):6501-7. doi: 10.1093/emboj/18.22.6501.
Dynamic changes in secondary structure of the 16S rRNA during the decoding of mRNA are visualized by three-dimensional cryo-electron microscopy of the 70S ribosome. Thermodynamically unstable base pairing of the 912-910 (CUC) nucleotides of the 16S RNA with two adjacent complementary regions at nucleotides 885-887 (GGG) and 888-890 (GAG) was stabilized in either of the two states by point mutations at positions 912 (C912G) and 885 (G885U). A wave of rearrangements can be traced arising from the switch in the three base pairs and involving functionally important regions in both subunits of the ribosome. This significantly affects the topography of the A-site tRNA-binding region on the 30S subunit and thereby explains changes in tRNA affinity for the ribosome and fidelity of decoding mRNA.
通过70S核糖体的三维冷冻电子显微镜观察,可视化了mRNA解码过程中16S rRNA二级结构的动态变化。16S RNA的912 - 910(CUC)核苷酸与885 - 887(GGG)和888 - 890(GAG)核苷酸处的两个相邻互补区域的热力学不稳定碱基配对,通过912位(C912G)和885位(G885U)的点突变在两种状态中的任何一种中得以稳定。可以追踪到一波重排,这是由三个碱基对的切换引起的,并且涉及核糖体两个亚基中功能重要的区域。这显著影响了30S亚基上A位点tRNA结合区域的拓扑结构,从而解释了tRNA对核糖体的亲和力变化以及mRNA解码的保真度。