S. cerevisiae Vts1p induces deadenylation-dependent transcript degradation and interacts with the Ccr4p-Pop2p-Not deadenylase complex

The Smaug family of sequence-specific RNA binding proteins regulates mRNA translation and degradation by binding to consensus stem–loop structures in target mRNAs. Vts1p is a member of the Smaug protein family that regulates the stability of target transcripts in Saccharomyces cerevisiae . Here we focus on the mechanism of Vts1p-mediated mRNA decay. Using RNA reporters that recapitulate Vts1p-mediated decay in vivo, we demonstrate that Vts1p stimulates mRNA degradation through deadenylation mediated by the Ccr4p-Pop2p-Not deadenylase complex. We also show that Vts1p interacts with the Ccr4p-Pop2p-Not complex suggesting that Vts1p recruits the Ccr4p-Pop2p-Not deadenylase complex to target mRNAs, resulting in transcript decay. Following deadenylation Vts1p target transcripts are decapped and subsequently degraded by the 5′-to-3′ exonuclease Xrn1p. Decapping and 5′-to-3′ decay is thought to occur in foci known as P-bodies, and we provide evidence that Vts1p function may involve P-bodies. Taken together with previous work, these data suggest that Smaug family members employ a conserved mechanism to induce transcript degradation that involves recruitment of the Ccr4-Pop2-Not deadenylase to target mRNAs.