Investigating novel genes with helicase activity involved in translation initiation

Translation is a conserved process in eukaryotic cells. Of203 genes involved in ribosome biogenesis and structure,176 are conserved between yeast and humans. During translation, RNA helicases unwind inhibitory secondary structural elements in the 5’ UTR of mRNAs enabling proper scanning of the mRNA for the AUG start codon identification. eIF4A is an RNA helicase initiation factor responsible for this unwinding activity. It has been reported that susceptibility to a number of cancers, and genetic disorders are associated with helicase activities during translation highlighting the importance of studying translation helicases and their control and regulations. To investigate the presence of additional genes that affect the activity of translation helicases we screened the yeast knockout gene collection for mutants with reduced ability to express a reporter gene under the control of a strong inhibitory structure on its 5’ mRNA. To this end we identified 26 genes that when deleted the expression of a B-glactosidase gene under the control of a strong 30 nt long stem-loop structure is reduced. Some of these factors seem to have independent helicase activities where as others appear to influence the activity of helicases including TIF2, DED1, DBP1 and FAL1. To further study the activity of the selected hits, their genetic interactions were examined using Synthetic Genetic Array (SGA) analysis. The selected hits all showed significant enrichment of genetic interaction with translation control genes. Our follow-up investigation with two of these genes, Mar1 and Kar1 suggested a general activity for these genes on the expression of different structured genes, namely PGM2 involved in LiCl detoxification.