The GATA-binding protein CGF-1 is closely related to GT-1.
Many light-regulated genes contain a conserved GATA motif in their 5'-upstream region. We have characterized in detail the GATA-binding factor, CGF-1, which bonds within a 73 bp TATA-proximal light/circadian regulatory element in the Arabidopsis cab2 promoter and to two more sites farther upstream. CGF-1 was found to be distinct from other metal-dependent GATA-binding factors, but to have the same sequence requirements for binding and similar physical and chemical properties as GT-1, a factor required for light regulation of the tobacco rbcS-3A gene. CGF-1 was found to be constitutively present in extracts and was shown to be immunologically related to GT-1. The close similarity between CGF-1 and GT-1 suggests that a GT-1-like factor is involved in the phytochrome/circadian regulation of the cab2 gene. CGF-1 and GT-1 were also found to have similar sequence specificities to another constitutively-regulated GATA factor, IBF-2b, which binds the I box region of the tomato nitrate reductase gene. Of three complexes detected using an IBF-2b-specific probe, only one was identical to CGF-1/GT-1. The other two were similar to IBF-2b, demonstrating that CGF-1/GT-1, although very similar, are actually distinct from IBF-2b. These data indicate that more than one factor can bind to the same short sequence and may indicate how constitutively present factors like GT-1 can play a role in light regulation.
Teakle
G R
GR
Department of Biology, University of Virginia, Charlottesville 22903, USA.
Kay
S A
SA
D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D002940:Circadian Rhythm; D017124:Conserved Sequence; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D008027:Light; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000096:biosynthesis / Q000378:metabolism*; D010947:Plants, Toxic; D011401:Promoter Regions, Genetic; D012273:Ribulose-Bisphosphate Carboxylase / Q000235:genetics; D016385:TATA Box; D014026:Nicotiana / Q000201:enzymology / Q000235:genetics; D014157:Transcription Factors / Q000096:biosynthesis / Q000378:metabolism*
D004268:DNA-Binding Proteins; C077926:GT-1 transcription factor; D009687:Nuclear Proteins; D014157:Transcription Factors; D012273:Ribulose-Bisphosphate Carboxylase