Autophagy-mediated Surveillance of Rim4-mRNA Interaction Safeguards Programmed Meiotic Translation

In yeast meiosis, autophagy is active and essential. Here, we investigate the fate of Rim4, a meiosis-specific RNA-binding protein (RBP), and its associated transcripts during meiotic autophagy. We demonstrate that Rim4 employs a nuclear localization signal (NLS) to enter the nucleus, where it loads its mRNA substrates before nuclear export. Upon reaching the cytoplasm, active autophagy selectively spares the Rim4-mRNA complex. During meiotic divisions, autophagy preferentially degrades Rim4 in an Atg11-dependent manner, coinciding with the release of Rim4-bound mRNAs for translation. Intriguingly, these released mRNAs also become vulnerable to autophagy. In vitro, purified Rim4 and its RRM-motif-containing variants activate Atg1 kinase in meiotic cell lysates and in immunoprecipitated (IP) Atg1 complexes. This suggests that the conserved RNA recognition motifs (RRMs) of Rim4 are involved in stimulating Atg1 and thereby facilitating selective autophagy. Taken together, our findings indicate that autophagy surveils Rim4-mRNA interaction to ensure stage-specific translation during meiosis.