Identifying a role for nonessential elF3 subunits eif-3.K and eif-3.L in the regulation of endoplasmic reticulum homeostasis and longevity in Caenorhabditis elegans

Abstract

The eukaryotic initiation factor 3 (elF3) is a protein complex composed of 13 subunits in mammals, and is an essential scaffold of the molecular interactions required for the formation of the 43S preinitiation complex (PIC). While these 13 subunits are broadly conserved within the eukaryotic phylogeny, both biochemical and evolutionary evidence suggests that translation initiation can proceed with a vastly reduced number of elF3 subunits, with as few as six subunits in the yeast species Saccharomyces cerevisiae. In this study, I report that homologs of eIF3 subunits elF3k and elF3I are nonessential in Caenorhabditis elegans, and that in their absence there is no defect in bulk protein translation. Surprisingly, mutants lacking these subunits exhibit both enhanced endoplasmic reticulum homeostasis and increased longevity, which implicates a potential regulatory role for these subunits in the maintenance of organismal physiology.