PLANT PHYSIOLOGY , Vol 112, Issue 2 727-733, Copyright © 1996 by American Society of Plant Biologists
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GENE REGULATION AND MOLECULAR GENETICS |
The Promoter for Tomato 3-Hydroxy-3-Methylglutaryl Coenzyme A Reductase Gene 2 Has Unusual Regulatory Elements That Direct High-Level Expression
N. D. Daraselia, S. Tarchevskaya and J. O. Narita
University of Illinois at Chicago, Laboratory for Molecular Biology, 900 South Ashland Avenue (M/C 567), Chicago, Illinois 60607
The promoter region of tomato (Lycopersicon esculentum)
3-hydroxy-3-methylglutaryl coenzyme A reductase gene 2 (HMG2) has been
analyzed using the transient expression of HMG2-luciferase fusions in red
fruit pericarp. The mRNA for HMG2 accumulates to high levels during fruit
ripening, in a pattern that coincides with the synthesis of the carotenoid
lycopene. Unlike most promoters, the region that is upstream of the HMG2
TATA element is not required for high-level expression. The 180-bp region
containing the TATA element, the 5[prime] untranslated region, and the
translation start site are comparable in strength to the full-length 35S
cauliflower mosaic virus promoter. Pyrimidine-rich sequences present in the
5[prime] untranslated leader are important in regulating expression. Also,
the ATG start region has been found to increase translation efficiency by a
factor of 4 to 10. An alternative hairpin secondary structure has been
identified surrounding the HMG2 initiator ATG, which could participate in
the translational regulation of this locus. HMG2 appears to be a novel
class of strong plant promoters that incorporate unusual, positive
regulators of gene expression.