Trihelix DNA-binding protein with specificities for two distinct cis-elements: both important for light down-regulated and dark-inducible gene expression in higher plants.
The DE1 sequence is a cis-regulatory element necessary and sufficient for light down-regulated and dark-inducible expression of the pea GTPase pra2 gene. This sequence does not show any sequence similarity to the previously reported ones involved in light-regulated gene expression. A one-hybrid screen isolated a cDNA encoding a DNA-binding protein, named DF1, with specificity for the DE1 sequence 5'-TACAGT. DF1 has domains similar to the trihelix DNA-binding domain found in the GT-1 and GT-2 proteins, which are plant transcription factors. The DE1-binding domain of DF1 is most similar to the carboxyl-terminal trihelix domain of the rice GT-2 protein with specificity for the GT2 sequence 5'-GGTAATT, which is also necessary for dark-inducible expression of the rice phyA gene. An electrophoretic mobility shift assay showed that this DNA-binding domain specifically binds to two types of DNA sequences, DE1 and GT2. Additionally, using DF1/GT-1 chimeras, we show that the second and third helices of the trihelix DNA-binding domain of DF1 are responsible for this dual DNA binding specificity. Our results show that DF1 has specificity for the two distinct cis-regulatory elements, both important for light down-regulated and dark-inducible gene expression in higher plants.
Nagano
Y
Y
Graduate School of Agricultural Sciences, Nagoya University, Nagoya 464-8601, Japan. nagano@agr.nagoya-u.ac.jp
Inaba
T
T
Furuhashi
H
H
Sasaki
Y
Y
D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D004247:DNA / Q000378:metabolism; D018076:DNA, Complementary; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003624:Darkness; D015536:Down-Regulation; D005786:Gene Expression Regulation; D008969:Molecular Sequence Data; D010944:Plants / Q000235:genetics* / Q000378:metabolism; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid
D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D004247:DNA