TY - JOUR
T1 - Abrogation of upstream open reading frame-mediated translational control of a plant S-adenosylmethionine decarboxylase results in polyamine disruption and growth perturbations
AU - Hanfrey, Colin
AU - Franceschetti, Marina
AU - Mayer, Melinda J.
AU - Illingworth, Crista
AU - Michael, Anthony J.
PY - 2002/11/15
Y1 - 2002/11/15
N2 - S-Adenosylmethionine decarboxylase (AdoMetDC) is a key enzyme in polyamine biosynthesis. We show that the plant AdoMetDC activity is subject to post-transcriptional control by polyamines. A highly conserved small upstream open reading frame (uORF) in the AdoMetDC mRNA 5′ leader is responsible for translational repression of a downstream β-glucuronidase reporter cistron in transgenic tobacco plants. Elimination of the small uORF from an AdoMetDC cDNA led to increased relative translational efficiency of the AdoMetDC proenzyme in transgenic plants. The resulting increased activity of AdoMetDC caused disruption to polyamine levels with depletion of putrescine, reduction of spermine levels, and a more than 400-fold increase in the level of decarboxylated S-adenosylmethionine. These changes were associated with severe growth and developmental defects. The high level of decarboxylated S-adenosylmethionine was not associated with any change in 5′-methylcytosine content in genomic DNA and S-adenosylmethionine levels were more or less normal, indicating a highly efficient system for maintenance of S-adenosylmethionine levels in plants. This work demonstrates that uORF-mediated translational control of AdoMetDC is essential for polyamine homeostasis and for normal growth and development.
AB - S-Adenosylmethionine decarboxylase (AdoMetDC) is a key enzyme in polyamine biosynthesis. We show that the plant AdoMetDC activity is subject to post-transcriptional control by polyamines. A highly conserved small upstream open reading frame (uORF) in the AdoMetDC mRNA 5′ leader is responsible for translational repression of a downstream β-glucuronidase reporter cistron in transgenic tobacco plants. Elimination of the small uORF from an AdoMetDC cDNA led to increased relative translational efficiency of the AdoMetDC proenzyme in transgenic plants. The resulting increased activity of AdoMetDC caused disruption to polyamine levels with depletion of putrescine, reduction of spermine levels, and a more than 400-fold increase in the level of decarboxylated S-adenosylmethionine. These changes were associated with severe growth and developmental defects. The high level of decarboxylated S-adenosylmethionine was not associated with any change in 5′-methylcytosine content in genomic DNA and S-adenosylmethionine levels were more or less normal, indicating a highly efficient system for maintenance of S-adenosylmethionine levels in plants. This work demonstrates that uORF-mediated translational control of AdoMetDC is essential for polyamine homeostasis and for normal growth and development.
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U2 - 10.1074/jbc.M206161200
DO - 10.1074/jbc.M206161200
M3 - Article
C2 - 12205086
AN - SCOPUS:0037113965
SN - 0021-9258
VL - 277
SP - 44131
EP - 44139
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 46
ER -