The different activities of the two activation domains of the Brn-3a transcription factor are dependent on the context of the binding site.
The POU (Pit-Oct-Unc) family transcription factor Brn-3a contains two distinct activation domains, one at the N terminus of the molecule and one at the C terminus coincident with the DNA binding domain. These different activation domains have been shown previously to differ in their ability to activate an artificial test promoter containing a Brn-3a binding site and the naturally occurring alpha-internexin gene promoter. Here we identify the target site for Brn-3a in the alpha-internexin gene promoter and show that it can confer responsiveness to Brn-3a on a heterologous promoter. One of the single-stranded DNA sequences derived from either this novel Brn-3a binding site or from the previously characterized site in the test promoter are shown to bind Brn-3a preferentially compared with the complementary single strand or the corresponding double-stranded sequence. The pattern of responsiveness of these two sequences when cloned upstream of the same test promoter and co-transfected with constructs encoding various portions of Brn-3a indicates that the activity of the two Brn-3a activation domains is dependent upon differences in the context of the target sequence in each promoter rather than on differences in the target sequence itself.
Budhram-Mahadeo
V
V
Department of Molecular Pathology, University College London Medical School, London W1P 6DB, United Kingdom.
Morris
P J
PJ
Lakin
N D
ND
Dawson
S J
SJ
Latchman
D S
DS
D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics*; D002460:Cell Line; D016384:Consensus Sequence; D006224:Cricetinae; D004277:DNA, Single-Stranded / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D007381:Intermediate Filament Proteins; D011401:Promoter Regions, Genetic; D013329:Structure-Activity Relationship; D050818:Transcription Factor Brn-3; D014157:Transcription Factors / Q000737:chemistry*; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection
D002352:Carrier Proteins; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D007381:Intermediate Filament Proteins; D050818:Transcription Factor Brn-3; D014157:Transcription Factors; C046643:alpha-internexin