Department of Molecular Genetics and Microbiology
Medical Subject Headings
RNA, Messenger; RNA Stability; Protein Biosynthesis; Introns; Nuclear Proteins; RNA-Binding Proteins; Saccharomyces cerevisiae Proteins; RNA Cap-Binding Proteins; RNA Caps
Microbiology | Molecular genetics
Intron-containing pre-mRNAs are normally retained and processed in the nucleus but are sometimes exported to the cytoplasm and degraded by the nonsense-mediated mRNA decay (NMD) pathway as a consequence of their inclusion of intronic in-frame termination codons. When shunted to the cytoplasm by autoregulated nuclear export, the intron-containing yeast YRA1 pre-mRNA evades NMD and is targeted by a cytoplasmic decay pathway mediated by the decapping activator Edc3p. Here, we have elucidated this transcript-specific decay mechanism, showing that Edc3p-mediated YRA1 pre-mRNA degradation occurs independently of translation and is controlled through five structurally distinct but functionally interdependent modular elements in the YRA1 intron. Two of these elements target the pre-mRNA as an Edc3p substrate and the other three mediate transcript-specific translational repression. Translational repression of YRA1 pre-mRNA also requires the heterodimeric Mex67p/Mtr2p general mRNA export receptor, but not Edc3p, and serves to enhance Edc3p substrate specificity by inhibiting the susceptibility of this pre-mRNA to NMD. Collectively, our data indicate that YRA1 pre-mRNA degradation is a highly regulated process that proceeds through translational repression, substrate recognition by Edc3p, recruitment of the Dcp1p/Dcp2p decapping enzyme, and activation of decapping.
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Citation: Dong S, Jacobson A, He F (2010) Degradation of YRA1 Pre-mRNA in the Cytoplasm Requires Translational Repression, Multiple Modular Intronic Elements, Edc3p, and Mex67p. PLoS Biol 8(4): e1000360. Link to article on publisher's website