m6A reader Pho92 is recruited co-transcriptionally and couples translation efficacy to mRNA decay to promote meiotic fitness in yeast [ime1D_ndt80D]

N6-methyladenosine (m6A) RNA modification impacts mRNA fate primarily via reader proteins, which dictate processes in development, stress, and disease. Yet little is known about m6A function in Saccharomyces cerevisiae, which occurs solely during early meiosis. Here we perform a multifaceted analysis of the m6A reader protein Pho92/Mrb1. Cross-linking immunoprecipitation analysis reveals that Pho92 associates with the 3’end of meiotic mRNAs in both an m6A-dependent and independent manner. Within cells, Pho92 transitions from the nucleus to the cytoplasm, and associates with translating ribosomes. In the nucleus Pho92 associates with target loci through its interaction with transcriptional elongator Paf1C. Functionally, we show that Pho92 promotes and links protein synthesis to mRNA decay. As such, the Pho92-mediated m6A-mRNA decay is contingent on active translation and the CCR4-NOT complex. We propose that the m6A reader Pho92 is loaded co-transcriptionally to facilitate correct translation and subsequent decay of m6A modified transcripts, and thereby promotes meiosis.N6-甲基腺嘌呤（N6-methyladenosine, m6A）RNA修饰主要通过m6A读取蛋白（m6A reader proteins）调控信使RNA（mRNA）的命运，此类读取蛋白主导了发育、胁迫与疾病中的核心生物学进程。然而人们对酿酒酵母（Saccharomyces cerevisiae）中m6A的功能却知之甚少，且该修饰仅出现于减数分裂早期。本研究针对m6A读取蛋白Pho92/Mrb1开展了多维度分析。交联免疫沉淀（cross-linking immunoprecipitation, CLIP）分析结果显示，Pho92可通过m6A依赖与非依赖两种方式，结合减数分裂相关mRNA的3'端区域。在细胞内，Pho92会从细胞核转移至细胞质，并与正在进行翻译的核糖体相结合。在细胞核内，Pho92可通过与转录延伸复合物Paf1C（transcriptional elongator Paf1C）相互作用，结合靶标基因座。从功能层面来看，本研究证实Pho92可促进蛋白质合成，并将该过程与mRNA降解过程相耦联。据此，Pho92介导的m6A修饰mRNA降解过程，依赖于活跃的翻译进程与CCR4-NOT复合物（CCR4-NOT complex）。本研究提出，m6A读取蛋白Pho92可在共转录阶段被招募，以保障m6A修饰转录本的正确翻译与后续降解，进而促进减数分裂进程。