TY - JOUR
T1 - A dual upstream open reading frame-based autoregulatory circuit controlling polyamine-responsive translation
AU - Hanfrey, Colin
AU - Elliott, Katherine A.
AU - Franceschetti, Marina
AU - Mayer, Melinda J.
AU - Illingworth, Crista
AU - Michael, Anthony J.
N1 - Copyright:
Copyright 2008 Elsevier B.V., All rights reserved.
PY - 2005/11/25
Y1 - 2005/11/25
N2 - 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.
AB - 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.
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U2 - 10.1074/jbc.M509340200
DO - 10.1074/jbc.M509340200
M3 - Article
C2 - 16176926
AN - SCOPUS:28244500966
SN - 0021-9258
VL - 280
SP - 39229
EP - 39237
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 47
ER -