Predicted RNA Binding Proteins Pes4 and Mip6 Regulate mRNA Levels, Translation, and Localization during Sporulation in Budding Yeast

In response to starvation, diploid cells ofSaccharomyces cerevisiae undergo meiosis and form haploid spores, a process collectively referred to as sporulation. The differentiation into spores requires extensive changes in gene expression. The transcriptional activator Ndt80 is a central regulator of this process, which controls many genes essential for sporulation. Ndt80 induces ∼300 genes coordinately during meiotic prophase, but different mRNAs within theNDT80 regulon are translated at different times during sporulation. The protein kinase Ime2 and RNA binding protein Rim4 are general regulators of meiotic translational delay, but how differential timing of individual transcripts is achieved was not known. This report describes the characterization of two relatedNDT80 -induced genes,PES4 andMIP6 , encoding predicted RNA binding proteins. These genes are necessary to regulate the steady-state expression, translational timing, and localization of a set of mRNAs that are transcribed byNDT80 but not translated until the end of meiosis II. Mutations in the predicted RNA binding domains withinPES4 alter the stability of target mRNAs.PES4 andMIP6 affect only a small portion of theNDT80 regulon, indicating that they act as modulators of the general Ime2/Rim4 pathway for specific transcripts.