title: Nascent peptide-mediated translation elongation arrest coupled with mRNA degradation in the CGS1 gene of Arabidopsis.
abstract: Expression of the Arabidopsis CGS1 gene that codes for cystathionine gamma-synthase is feedback regulated at the step of mRNA stability in response to S-adenosyl-L-methionine (AdoMet). A short stretch of amino acid sequence, called the MTO1 region, encoded by the first exon of CGS1 itself is involved in this regulation. Here, we demonstrate, using a cell-free system, that AdoMet induces temporal translation elongation arrest at the Ser-94 codon located immediately downstream of the MTO1 region, by analyzing a translation intermediate and performing primer extension inhibition (toeprint) analysis. This translation arrest precedes the formation of a degradation intermediate of CGS1 mRNA, which has its 5' end points near the 5' edge of the stalled ribosome. The position of ribosome stalling also suggests that the MTO1 region in nascent peptide resides in the ribosomal exit tunnel when translation elongation is temporarily arrested. In addition to the MTO1 region amino acid sequence, downstream Trp-93 is also important for the AdoMet-induced translation arrest. This is the first example of nascent peptide-mediated translation elongation arrest coupled with mRNA degradation in eukaryotes. Furthermore, our data suggest that the ribosome stalls at the step of translocation rather than at the step of peptidyl transfer.
authors: Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University, Sapporo 060-8589, Japan.
authors: Hitoshi
authors: H
authors: Onouchi
authors: Yoko
authors: Y
authors: Nagami
authors: Yuhi
authors: Y
authors: Haraguchi
authors: Mari
authors: M
authors: Nakamoto
authors: Yoshiko
authors: Y
authors: Nishimura
authors: Ryoko
authors: R
authors: Sakurai
authors: Nobuhiro
authors: N
authors: Nagao
authors: Daisuke
authors: D
authors: Kawasaki
authors: Yoshitomo
authors: Y
authors: Kadokura
authors: Satoshi
authors: S
authors: Naito
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics*; D019757:Carbon-Oxygen Lyases / Q000235:genetics*; D017343:Genes, Plant; D010441:Peptide Chain Elongation, Translational / Q000502:physiology*; D010455:Peptides / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*
chemical_list: D010455:Peptides; D012333:RNA, Messenger; C022696:O-succinylhomoserine (thiol)-lyase; D019757:Carbon-Oxygen Lyases