A dual upstream open reading frame-based autoregulatory circuit controlling polyamine-responsive translation

Colin Hanfrey, Katherine A. Elliott, Marina Franceschetti, Melinda J. Mayer, Crista Illingworth, Anthony J. Michael

Research output: Contribution to journalArticle

102 Scopus citations

Abstract

A novel form of translational regulation is described for the key polyamine biosynthetic enzyme S-adenosylmethionine decarboxylase (AdoMetDC). Plant AdoMetDC mRNA 5′ leaders contain two highly conserved overlapping upstream open reading frames (uORFs): the 5′ tiny and 3′ small uORFs, We demonstrate that the small uORF-encoded peptide is responsible for constitutively repressing downstream translation of the AdoMetDC proenzyme ORF in the absence of increased polyamine levels. This first example of a sequence-dependent uORF to be described in plants is also functional in Saccharomyces cerevisiae. The tiny uORF is required for normal polyamine-responsive AdoMetDC mRNA translation, and we propose that this is achieved by control of ribosomal recognition of the occluded small uORF, either by ribosomal leaky scanning or by programmed -1 frameshifting. In vitro expression demonstrated that both the tiny and the small uORFs are translated. This tiny/small uORF configuration is highly conserved from moss to Arabidopsis thaliana, and a more diverged tiny/small uORF arrangement is found in the AdoMetDC mRNA 5′ leader of the single-celled green alga Chlamydomonas reinhardtii, indicating an ancient origin for the uORFs.

Original languageEnglish (US)
Pages (from-to)39229-39237
Number of pages9
JournalJournal of Biological Chemistry
Volume280
Issue number47
DOIs
StatePublished - Nov 25 2005

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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