New structural insights into cap‐independent translation initiation (566.6)

Abstract

Conventional initiation of translation of cellular mRNAs depends on the m7G cap located at the 5' untranslated region (UTR) and on extraribosomal proteins called initiation factors. Translation of many viral mRNAs and some cellular mRNAs can be initiated in a cap‐independent manner, with fewer initiation factors, to promote expression under stress conditions when overall cellular translation is downregulated. In these mechanisms, several types of structured RNA at the 5' UTR are employed, called the internal ribosome entry sites (IRES). The structural basis for how an IRES binds to the ribosome and positions the open reading frame of mRNA is not fully understood. Here, we present molecular structures of ribosome complexes, which provide new structural insights into the mechanism of IRES‐dependent translation.Grant Funding Source: Supported by HHMI and National Institutes of Health