Crystal structure of elongation factor 4 bound to a clockwise ratcheted ribosome.
Publication Type:Journal Article
Source:Science, Volume 345, Issue 6197, p.684-7 (2014)
Keywords:Crystallography, X-Ray, Escherichia coli Proteins, Nucleic Acid Conformation, Peptide Initiation Factors, Protein Structure, Tertiary, Ribosome Subunits, Small, Bacterial, RNA, Transfer, Thermus thermophilus, Transcriptional Elongation Factors
<p>Elongation factor 4 (EF4/LepA) is a highly conserved guanosine triphosphatase translation factor. It was shown to promote back-translocation of tRNAs on posttranslocational ribosome complexes and to compete with elongation factor G for interaction with pretranslocational ribosomes, inhibiting the elongation phase of protein synthesis. Here, we report a crystal structure of EF4-guanosine diphosphate bound to the Thermus thermophilus ribosome with a P-site tRNA at 2.9 angstroms resolution. The C-terminal domain of EF4 reaches into the peptidyl transferase center and interacts with the acceptor stem of the peptidyl-tRNA in the P site. The ribosome is in an unusual state of ratcheting with the 30S subunit rotated clockwise relative to the 50S subunit, resulting in a remodeled decoding center. The structure is consistent with EF4 functioning either as a back-translocase or a ribosome sequester. </p>