Elongation Factor G Bound to the Ribosome in an Intermediate State of Translocation

Abstract

Revealed in Translation The ribosome, with the help of transfer RNAs (tRNAs), converts the triple genetic code in messenger RNA (mRNA) into protein. Upon decoding of a codon, the mRNA and associated tRNAs must be moved through the ribosome, so that the next codon can be read, with a new charged tRNA taken in at the A (aminoacyl-tRNA) site, the newly extended peptidyl-tRNA moved into the P (peptidyl-tRNA) site, and the deacylated tRNA removed from the exit site in the ribosome (see the Perspective by Rodnina ). Crystal structures from Tourigny et al. (p. 1235490 ), Pulk and Cate (p. 1235970 ), and Zhou et al. (p. 1236086 ), variously capture the prokaryotic ribosome during this translocation phase, revealing the hybrid states of the tRNAs and the substantial motions of the 30S ribosomal subunit during the process, the role of elongation factor G, and suggest how the direction and reading frame of the mRNA is maintained.