Abstract
In the course of studies on post-transcriptional regulation of the Arabidopsis CGS1 gene, which encodes the key enzyme of methionine biosynthesis, we have found that a specific region of the nascent CGS1 polypeptide acts within the ribosome to cause translational elongation arrest in response to S-adenosylmetionine, which is followed by mRNA degradation. In this study, we addressed the question of whether nascent-peptide-mediated ribosome stalling is generally coupled with mRNA degradation in plants, by using an upstream ORF (uORF) system in which the uORF-encoded nascent peptide causes ribosome stalling at the stop codon of the uORF. Promotion of mRNA decay was observed when uORF peptide-mediated ribosome stalling was induced in Arabidopsis callus culture. Since a uORF-contaning genes can be a target of nonsense-medeated mRNA decay (NMD), we are testing the possibility that NMD is involved in the observed mRNA degradation.
