SOLUTION STRUCTURE OF A TBP-TAF(II)230 COMPLEX - PROTEIN MIMICRY OF THE MINOR-GROOVE SURFACE OF THE TATA BOX UNWOUND BY TBP

General transcription factor TFIID consists of TATA box-binding protei n (TBP) and TBP-associated factors (TAF(II)s), which together play a c entral role in both positive and negative regulation of transcription. The N-terminal region of the 230 kDa Drosophaa TAF(II)(dTAF(II)230) b inds directly to TBP and inhibits TBP binding to the TATA box. We repo rt here the solution structure of the complex formed by dTAF(II)230 N- terminal region (residues 11-77) and TBP. dTAF(II)230(11-77) comprises three or helices and a beta hairpin, forming a core that occupies the concave DNA-binding surface of TBP. The TBP-binding surface of dTAF(I I)230 markedly resembles the minor groove surface of the partially unw ound TATA box in the TBP-TATA complex. This protein mimicry of the TAT A element surface provides the structural basis of the mechanism by wh ich dTAF(II)230 negatively controls the TATA box-binding activity with in the TFIID complex.