*** MONDAY, October 9th ***
Initiation of mRNA translation is a key regulatory step in gene expression in all eukaryotes. Canonical initiation of translation in eukaryotes involves recruitment of the 43S pre-initiation complex to the 5′ end of mRNA by the cap-binding complex eIF4F to form the 48S initiation complex (48S), followed by scanning along the mRNA until the start codon is selected. I will discuss our work on the structure of a 48S complex on mRNAs without and with a start codon. In addition to the eIF4A that is part of eIF4F, there is a second eIF4A helicase bound to the mRNA entry site. The entry channel bound eIF4A is positioned through interactions with eIF3 and the 40S subunit to enable its ATP-dependent helicase activity to directly unwind secondary structure located downstream of the scanning 48S complex. The structure also reveals universally conserved interactions between eIF4F and the 48S, likely explaining how this complex can promote mRNA recruitment in eukaryotes.
Prof. Ramakrishnan will also present the IGB Pioneers Seminar on Tuesday, October 10, 2023