| Start codon recognition is a crucial event in initiation, committing the ribosome to beginning translation from a particular location; starting translation in the wrong location will fail to produce the desired protein and result in an incorrect and possibly toxic peptide. To investigate the mechanism of start codon recognition in eukaryotes, we used a reconstituted system of S. cerevisiae components. We show that base pairing between the initiator tRNA anticodon and the mRNA start codon results in a conformational change of the pre-initiation complex to a more stable state, likely the previously proposed "closed" state that arrests the movement of the complex on the mRNA. We provide evidence that a conformational change in the initiator tRNA is involved in transmitting to the rest of the complex this signal that matching anticodon/start codon base pairing has been achieved. |
