H. Xiao et al., RECRUITING TATA-BINDING PROTEIN TO A PROMOTER - TRANSCRIPTIONAL ACTIVATION WITHOUT AN UPSTREAM ACTIVATOR, Molecular and cellular biology, 15(10), 1995, pp. 5757-5761
The binding of TATA-binding protein (TBP) to the TATA element is the f
irst step in the initiation of RNA polymerase II transcription from ma
ny promoters in vitro. It has been proposed that upstream activator pr
oteins stimulate transcription by recruiting TBP to the promoter, thus
facilitating the assembly of a transcription complex. However, the ro
le of activator proteins acting at this step to stimulate transcriptio
n in vivo remains largely speculative, To test whether recruitment of
TBP to the promoter is sufficient for transcriptional activation in vi
vo, we constructed a hybrid protein containing TBP of the yeast Saccha
romgces cerevisiae fused to the DNA-binding domain of GAL4. Our result
s show that TBP recruited by the GAL4 DNA-binding domain to promoters
bearing a GAL4-binding site can interact with the TATA element and dir
ect high levels of transcription. This finding indicates that binding
of TBP to promoters in S. cerevisiae is a major rate-limiting step acc
elerated by upstream activator proteins.