Core Promoter Binding by Histone-Like TAF Complexes

Abstract

A major function of TFIID is core promoter recognition. TFIID consists of TATA-binding protein (TBP) and 14 TBP-associated factors (TAFs). Most of them contain a histone fold domain (HFD) that lacks the DNA-contacting residues of histones. Whether and how TAF HFDs contribute to core promoter DNA binding are yet unresolved. Here we examined the DNA binding activity of TAF9, TAF6, TAF4b, and TAF12, which are related to histones H3, H4, H2A, and H2B, respectively. Each of these TAFs has intrinsic DNA binding activity adjacent to or within the HFD. The DNA binding domains were mapped to evolutionarily conserved and essential regions. Remarkably, HFD-mediated interaction enhanced the DNA binding activity of each of the TAF6-TAF9 and TAF4b-TAF12 pairs and of a histone-like octamer complex composed of the four TAFs. Furthermore, HFD-mediated interaction stimulated sequence-specific binding by TAF6 and TAF9. These results suggest that TAF HFDs merge with other conserved domains for efficient and specific core promoter binding.

ACKNOWLEDGMENTS

We thank P. Anthony Weil for the TAF4 null yeast strain, Irwin Davidson for the TAF12 antibody, Laszlo Tora for the TAF6 antibody, Arthur Liberzon for indicating to us the temperature sensitivity phenotype of the yTAF4 151-388Δ311-350 strain, and R. Tjian and Elena Ainbinder for their comments on parts of the manuscript.

This work was supported by grants from the Israel Science Foundation, the Woman Health Research Center of the Weizmann Institute of Science, and the Minerva Foundation of Germany. R.D. is an incumbent of the Martha S. Sagon Career Development Chair.