Poly(A) tail length regulates gene expression in yeast meiosis

Degradation of the poly(A) tail is the first step of the main RNA decay pathway, and it has hence been proposed that the length of the tail controls gene stability. However, it remains unclear how general this effect is, given that high throughput studies in various systems generally find only very poor correlation between tail length and RNA half-life. In the budding yeast, Saccharomyces cerevisiae, meiosis is induced under starvation, triggering a complex transcriptional program which lead to spore formation, providing a biological context to study poly(A) tail role in dynamic gene expression regulation.

The goal of this work is to study the effect of poly(A) tail in gene expression using yeast meiosis as a model. To measure poly(A) tail length we developed a high-throughput sequencing based method and generated detailed maps of poly(A) lengths across yeast meiosis. First, we detected a dynamic profile of tail changes across meiosis which recapitulates meiotic progression. In addition, we observed a positive correlation between half-life and poly(A) tail length specifically in meiosis and absent under vegetative growth conditions. Interestingly the correlation between gene expression and codon optimality, one of the major factors regulating stability under vegetative growth conditions is significantly diminished in meiosis. These results suggest a model where in contrast to vegetative conditions in which RNA stability is regulated by codon optimality in meiosis is the poly(A) tail length which plays a central role in dictating gene expression.