Solution Structure of a TBP–TAF II230 Complex : Protein Mimicry of the Minor Groove Surface of the TATA Box Unwound by TBP

Abstract

General transcription factor TFIID consists of TATA box–binding protein (TBP) and TBP-associated factors (TAF IIs), which together play a central role in both positive and negative regulation of transcription. The N-terminal region of the 230 kDa Drosophila TAF II (dTAF II230) binds directly to TBP and inhibits TBP binding to the TATA box. We report here the solution structure of the complex formed by dTAF II230 N-terminal region (residues 11–77) and TBP. dTAF II230 11–77 comprises three α helices and a β hairpin, forming a core that occupies the concave DNA-binding surface of TBP. The TBP-binding surface of dTAF II230 markedly resembles the minor groove surface of the partially unwound TATA box in the TBP–TATA complex. This protein mimicry of the TATA element surface provides the structural basis of the mechanism by which dTAF II230 negatively controls the TATA box–binding activity within the TFIID complex.