2011/07/18

The Cryo-EM Structure of a Complete 30S Translation Initiation Complex from Escherichia coli

Researchers from CICbioGUNE in collaboration with the Max Planck Institute for Biophysical Chemistry have described the first initiation complex for E. coli ribosomes during translation.

The selection of mRNA, of the correct start codon, and of the initiator fMet-tRNAfMet requires the presence of three initiation factors (IF1, IF2, IF3). By cryoEM and classification techniques the structure of a complete 30S initiation complex from E. coli was described and identified positions and orientations of initiation factors and tRNA. The 30S subunit is found in a rotated conformation, which may be essential for rapid joining of the 50S subunit and the regulation of the mRNA selection. Visualization of IF3 gives insight into its role in preventing association of ribosomal subunits. The results are important for understanding how the interplay of elements during the early stages of translation provides selection and regulates the progression towards competent translating 70S ribosomes. The findings have been published in the last issue of PLOS Biology