Drosophila Mediator Complex Is Broadly Utilized by Diverse Gene-Specific Transcription Factors at Different Types of Core Promoters

Abstract

To decipher the mechanistic roles of Mediator proteins in regulating developmental specific gene expression and compare them to those of TATA-binding protein (TBP)-associated factors (TAFs), we isolated and analyzed a multiprotein complex containingDrosophila Mediator (dMediator) homologs. dMediator interacts with several sequence-specific transcription factors and basal transcription machinery and is critical for activated transcription in response to diverse transcriptional activators. The requirement for dMediator did not depend on a specific core promoter organization. By contrast, TAFs are preferentially utilized by promoters having a specific core element organization. Therefore, Mediator proteins are suggested to act as a pivotal coactivator that integrates promoter-specific activation signals to the basal transcription machinery.

ACKNOWLEDGMENTS

We thank Carl Wu for providing Drosophila embryo nuclear extracts used in the initial stage of dMediator purification and also for helpful comments on the manuscript; Gaku Mizuguchi for purified TFIIH; Hua Xiao, James Kadonaga, Yoshihiro Nakatani, Marc Vigneron, Erich Nigg, James Manley, David Allis, Michael Levine, Arnold Berk, Albert Courey, Pierr Léopold, Peter Becker, Arno Greenleaf, Michael Carey, David Price, Magaret Fuller, and William Zehring for plasmids, baculovirus constructs, and antibodies; our colleagues in the Kim lab for helpful discussion; and Jennifer Macke for substantive editing of the text. J.M.P. thanks Dolph Hatfield for support and encouragement.

J.-G.K. is a National Institutes of Health Fogarty International Center Visiting Fellow and is supported by the Division of Basic Sciences, National Cancer Institute. This work was supported by the Creative Research Initiatives Program from the Korean Ministry of Science and Technology to Y.-J.K.