title: Ribosome stacking defines CGS1 mRNA degradation sites during nascent peptide-mediated translation arrest.
abstract: Expression of the Arabidopsis CGS1 gene that codes for cystathionine gamma-synthase is feedback-regulated at the step of mRNA degradation in response to S-adenosyl-L-methionine (AdoMet). This regulation occurs during translation and involves AdoMet-induced temporal translation arrest prior to the mRNA degradation. Here, we have identified multiple intermediates of CGS1 mRNA degradation with different 5' ends that are separated by approximately 30 nucleotides. Longer intermediates were found to be produced as the number of ribosomes loaded on mRNA was increased. Sucrose density gradient centrifugation experiments showed that the shortest mRNA degradation intermediate was associated with monosomes, whereas longer degradation intermediates were associated with multiple ribosomes. Immunoblot analyses revealed a ladder of premature polypeptides whose molecular weights corresponded to products of ribosomes in a stalled stack. An increase in smaller premature polypeptides was observed as the number of ribosomes loaded on mRNA increased. These results show that AdoMet induces the stacking of ribosomes on CGS1 mRNA and that multiple mRNA degradation sites probably correspond to each stacked ribosome.
authors.affiliation: Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University, Kita-ku, Sapporo 060-8589, Japan.
authors.forename: Yuhi
authors.initials: Y
authors.lastname: Haraguchi
authors.forename: Yoshitomo
authors.initials: Y
authors.lastname: Kadokura
authors.forename: Mari
authors.initials: M
authors.lastname: Nakamoto
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Onouchi
authors.forename: Satoshi
authors.initials: S
authors.lastname: Naito
mesh_terms: D017360:Arabidopsis / Q000166:cytology* / Q000235:genetics* / Q000378:metabolism; D019757:Carbon-Oxygen Lyases / Q000235:genetics*; D018506:Gene Expression Regulation, Plant; D014176:Protein Biosynthesis; D020871:RNA Stability; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism*; D012436:S-Adenosylmethionine
chemical_list: D012333:RNA, Messenger; D018749:RNA, Plant; D012436:S-Adenosylmethionine; C022696:O-succinylhomoserine (thiol)-lyase; D019757:Carbon-Oxygen Lyases