TFIID can be rate limiting in vivo for TATA-containing, but not TATA-lacking, RNA polymerase II promoters. (original) (raw)

  1. J Colgan and
  2. J L Manley
  3. Department of Biological Sciences, Columbia University, New York, New York 10027.

Abstract

We have studied the effect of exogenous expression of the basal transcription factor TFIID on the activities of several different TATA-containing and TATA-lacking promoters. Overexpression of TFIID from a transfected plasmid in Drosophila Schneider cells resulted in substantial concentration-dependent increases in expression from a cotransfected minimal TATA-containing promoter. Overexpression of TFIID activated expression from all TATA-containing promoters tested, with the maximum level of activation being inversely proportional to the strength of the promoter. In contrast, expression from TATA-less promoters was not enhanced, and could in fact be reduced, by increased expression of TFIID. Consistent with these findings overexpression of TFIID had opposite effects on Sp1-mediated activation observed from minimal synthetic promoters consisting of Sp1-binding sites and either a TATA box or initiator element. We discuss the significance of these results in terms of the role of TFIID in the initiation of transcription and as a possible regulatory target for expression from TATA-containing promoters, as well as the role TFIID may play in expression from TATA-less promoters.

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