Molecular dissection of GT-1 from Arabidopsis.
We isolated and characterized an Arabidopsis cDNA encoding the DNA binding protein GT-1. This protein factor, which contains 406 amino acids, is highly homologous to the previously described tobacco DNA binding protein GT-1a/B2F but is 26 amino acids longer. Recombinant Arabidopsis GT-1, which was obtained from in vitro translation, bound to probes consisting of four copies of pea small subunit of ribulose bisphosphate carboxylase rbcS-3A box II and required the same GGTTAA core binding site as the binding activity of an Arabidopsis nuclear protein preparation. However, unlike the truncated tobacco GT-1a prepared from Escherichia coli extracts, the full-length Arabidopsis GT-1 bound to pea rbcS-3A box III and Arabidopsis chlorophyll a/b binding protein CAB2 light-responsive elements, both of which contain GATA motifs. Deletion and mutational analyses suggested that the predicted trihelix region of GT-1 is essential for DNA binding. Moreover, GT-1 binds to target DNA as a dimer, and its C-terminal region contains a putative dimerization domain that enhances the binding activity. Transient expression of the GT-1::beta-glucuronidase fusion protein in onion cells revealed the presence of a nuclear localization signal(s) within the first 215 amino acids of GT-1.
Hiratsuka
K
K
Laboratory of Plant Molecular Biology, Rockefeller University, New York, New York 10021-6399.
Wu
X
X
Fukuzawa
H
H
Chua
N H
NH
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics*; D001483:Base Sequence; D002467:Cell Nucleus / Q000378:metabolism; D018076:DNA, Complementary; D018744:DNA, Plant; D004268:DNA-Binding Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010940:Plant Proteins / Q000235:genetics*; D011994:Recombinant Proteins / Q000235:genetics; D017384:Sequence Deletion
D018076:DNA, Complementary; D018744:DNA, Plant; D004268:DNA-Binding Proteins; D010940:Plant Proteins; D011994:Recombinant Proteins; C077485:GT-1a protein, Nicotiana tabacum