Global analysis of mRNA isoform half-lives: identification of stabilizing and destabilizing elements in yeast

We measured half-lives of 21,248 mRNA 3’ isoforms in yeast by rapidly depleting RNA polymerase II from the nucleus and performing direct RNA sequencing throughout the decay process. Interestingly, the half-lives of mRNA isoforms from the same gene, including nearly identical isoforms, often vary widely. Based on clusters of isoforms with different half-lives, we identify hundreds of sequences conferring stabilization or destabilization upon mRNAs terminating downstream. One class of stabilizing element is a polyU sequence that can interact with poly(A) tails, inhibit the association of poly(A) binding protein, and confer increased stability upon introduction into ectopic transcripts. More generally, destabilization and stabilization elements are linked to the degree to which the poly(A) tail can engage in double-stranded structures. Isoforms engineered to fold into 3’ stem-loop structures not involving the poly(A) tail exhibit even longer half-lives. We suggest that double-stranded structures at the 3’ ends are a major determinant of mRNA stability. Half-lives of 21,248 mRNA 3’ isoforms in yeast were measured by rapidly depleting RNA polymerase II from the nucleus and performing direct RNA sequencing throughout the decay process.