PLANT PHYSIOLOGY , Vol 112, Issue 4 1563-1571, Copyright © 1996 by American Society of Plant Biologists
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GENE REGULATION AND MOLECULAR GENETICS |
Cis-Acting Elements Essential for Light Regulation of the Nuclear Gene Encoding the A Subunit of Chloroplast Glyceraldehyde 3-Phosphate Dehydrogenase in Arabidopsis thaliana
S. C. Park, H. B. Kwon and M. C. Shih
Department of Biological Sciences, University of Iowa, Iowa City, Iowa 52242
We report the characterization of cis-acting elements involved in light
regulation of the nuclear gene (GapA) that encodes the A subunit of
glyceraldehyde 3-phosphate dehydrogenase in Arabidopsis thaliana. Our
previous deletion analyses indicate that the -277 to -195 upstream region
of GapA is essential for light induction of the [beta]-glucuronidase
reporter gene in transgenic tobacco (Nicotiana tabacum) plants. This region
contains three direct repeats with the consensus sequence
5[prime]-CAAATGAA(A/G)A-3[prime] (Gap boxes). Our results show that 2-bp
substitutions of the last four nucleotides (AA or GA) of the Gap boxes by
CC abolish light induction of the [beta]-glucuronidase reporter gene in
vivo and affect binding of the Gap box binding factor in vitro. We have
also identified an additional cis-acting element, AE (Activation Element)
box, that is involved in regulation of GapA. A combination of a Gap box
trimer and an AE box dimer can confer light responsiveness on the
cauliflower mosaic virus 35S promoter containing the -92 to +6 upstream
sequence, whereas oligomers of Gap boxes or AE boxes alone cannot confer
light responsiveness on the same promoter. These results suggest that Gap
boxes and AE boxes function together as the light-responsive element of
GapA.
