Characterization of a gene encoding a DNA binding protein with specificity for a light-responsive element.
The sequence element of box II (GTGTGGTTAATATG) is a regulatory component of a light-responsive element present within the upstream region of pea rbcS-3A. The nuclear protein GT-1 was defined previously as a DNA binding activity that interacts with box II. Here, we describe the isolation and characterization of cDNA sequences that encode a DNA binding protein with specificity for this element. The recombinant protein, tobacco GT-1a, shows similar sequence requirements for DNA binding to nuclear GT-1, as assayed by its ability to interact with previously defined 2-bp scanning mutations of box II, and is shown to be immunologically related to nuclear GT-1. The predicted structure of the 43-kD protein derived from the cDNA sequence suggests the presence of a novel helix-helix-turn-helix (HHTH) motif. Comparison between the predicted protein sequence encoded by the tobacco GT-1a cDNA and that of another GT binding protein, rice GT-2, reveals strong amino acid conservation over the HHTH region; this motif appears to be involved in the interaction between the recombinant protein and box II. Genomic DNA gel blot analysis indicated the presence of a small gene family of related sequences within the tobacco nuclear genome. RNA gel blot analysis of tobacco mRNA using the isolated cDNA as a probe showed that transcripts are present in several tissues, including both light-grown and dark-adapted leaves.
Gilmartin
P M
PM
Laboratory of Plant Molecular Biology, Rockefeller University, New York, New York 10021-6399.
Memelink
J
J
Hiratsuka
K
K
Kay
S A
SA
Chua
N H
NH
D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D004247:DNA; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D008027:Light; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D010947:Plants, Toxic; D012045:Regulatory Sequences, Nucleic Acid; D012273:Ribulose-Bisphosphate Carboxylase / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D014026:Nicotiana / Q000235:genetics*; D014158:Transcription, Genetic / Q000528:radiation effects
D004268:DNA-Binding Proteins; D010940:Plant Proteins; C077485:GT-1a protein, Nicotiana tabacum; D004247:DNA; D012273:Ribulose-Bisphosphate Carboxylase