eIF3 mediates translational heat shock response through the RNA-binding g subunit

 

Katsura Asano

 

Division of Biology, Kansas State University, USA

 

Graduate School of Integrated Sciences for Life & Hiroshima Research Center for Healthy Aging, Hiroshima University, Japan

 

While heat shock response is crucial for protein folding homeostasis and the rapid growth of cells including cancer, its translational control remains a mystery. Here, we performed genome-wide translational profiling of yeast temperature-sensitive mutant mapping in the i subunit of translation factor eIF3 [1] and found that, along with its RNA-binding partner, eIF3g, it promotes translation of a subset of mRNA in response to heat. The eIF3i/g-regulated genes include SSA1/2 encoding Hsp70. Its translational control is mediated by direct eIF3g-binding to the GUCG motif located 12-bases downstream of the start codon. SELEX analysis indicates that eIF3g binds a consensus AGUCGGU through its RRM. We propose that eIF3g binding to the leading edge of mRNA within the scanning pre-initiation complex promotes translation initiation from a subset of mRNAs in response to heat.

 

[1] Asano, K.  et al, J. Biol. Chem. 1998, 273, 18573-18585.