The histone folds in transcription factor TFIID

Abstract

The transcription factor TFIID is a multimeric protein complex containing the TATA box-binding polypeptide (TBP) and TBP-associated factors. We have previously reported that the N-terminal regions of dTAF(II)62 and dTAF(II)42 have sequence similarities with histones H4 and H3. Here, we demonstrate that the histone-homologous regions of dTAF(II)62 and dTAF(II)42 form a heteromeric complex both in vitro and in a yeast two-hybrid system. Neither dTAF(II)62 nor dTAF(II)42 forms a homomeric complex, in agreement with a nucleosomal histone character. Moreover, circular dichroism measurements show that the heteromeric complex is dominated by α-helical secondary structure. These results strongly suggest the existence of a histone-like surface on TFIID.