부산대학교 도서관

Peptide-chain elongation during protein synthesis entails sequential aminoacyl-tRNA selection and translocation reactions that proceed rapidly (2-20 per second) and with a low error rate (around 10.sup.-3 to 10.sup.-5 at each step) over thousands of cycles.sup.1. The cadence and fidelity of ribosome transit through mRNA templates in discrete codon increments is a paradigm for movement in biological systems that must hold for diverse mRNA and tRNA substrates across domains of life. Here we use single-molecule fluorescence methods to guide the capture of structures of early translocation events on the bacterial ribosome. Our findings reveal that the bacterial GTPase elongation factor G specifically engages spontaneously achieved ribosome conformations while in an active, GTP-bound conformation to unlock and initiate peptidyl-tRNA translocation. These findings suggest that processes intrinsic to the pre-translocation ribosome complex can regulate the rate of protein synthesis, and that energy expenditure is used later in the translocation mechanism than previously proposed. Cryo-electron microscopy and single-molecule fluorescence methods are used to elucidate the mechanism of early translocation events on the bacterial ribosome.
Author(s): Emily J. Rundlet [sup.1] [sup.2] , Mikael Holm [sup.1] , Magdalena Schacherl [sup.3] , S. Kundhavai Natchiar [sup.1] , Roger B. Altman [sup.1] , Christian M. T. Spahn [sup.3] [...]