Poster abstracts
Poster number 8 submitted by Daisy DiVita
Investigating the inhibitory role of initiation factor eIF2A on translation in vitro
Daisy J. DiVita (The Ohio State Biochemistry Program, Department of Biological Chemistry and Pharmacology, Center for RNA Biology, The Ohio State University, Columbus, OH 43210), Michael G. Kearse (The Ohio State Biochemistry Program, Department of Biological Chemistry and Pharmacology, Center for RNA Biology, The Ohio State University, Columbus, OH 43210)
Abstract:
Canonical translation uses the heterotrimeric eukaryotic initiation factor 2 (eIF2) as the initiator tRNA (tRNAiMet) carrier and as a central node of regulation. However, eIF2 was not the first tRNAiMet carrier identified in eukaryotes. eIF2A (a monomer that is non-homologous to eIF2) was the initial tRNAiMet binding protein discovered, but its role in translation was overshadowed after eIF2 was identified. Recent reports have shown that eIF2A is required for cancer progression, not part of the canonical set of initiator factors, displays uncharacteristic GTP-independence for tRNA binding (unlike other tRNA-binding translation factors), and is able to stimulate initiation at CUG codons using Leu-tRNACUG; however, the exact function of eIF2A remains unknown. To determine how eIF2A functions in translation initiation, we programed in vitro translation extracts with recombinant human eIF2A. Our preliminary data show a 30-fold decrease in reporter activity when recombinant eIF2A is present, suggesting eIF2A is an inhibitor of translation. Here we will pursue testing whether eIF2A is competing for tRNAiMet or inhibiting 80S formation. Together, these mechanistic insights will shed light on how non-canonical initiation factors are used and regulate eukaryotic translation.
Keywords: Translational control, Ribosome, Protein synthesis