The amino-terminal tails of the core histones and the translational position of the TATA box determine TBP/TFIIA association with nucleosomal DNA.

We establish that the TATA binding protein (TBP) in the presence of TFIIA recognizes the TATA box in nucleosomal DNA dependent on the dissociation of the amino-terminal tails of the core histones from the nucleosome and the position of the TATA box within the nucleosome. We examine TBP/TFIIA access to the TATA box with this sequence placed in four distinct rotational frames with reference to the histone surface and at three distinct translational positions at the edge, side and dyad axis of the nucleosome. Under our experimental conditions, we find that the preferential translational position at which TBP/TFIIA can bind the TATA box is within linker DNA at the edge of the nucleosome and that binding is facilitated if contacts made by the amino-terminal tails of the histones with nucleosomal DNA are eliminated. TBP/TFIIA binding to DNA at the edge of the nucleosome occurs with the TATA box in all four rotational positions. This is indicative of TBP/TFIIA association directing the dissociation of the TATA box from the surface of the histone octamer.     

Signals for TBP/TATA box recognition

The TATA box-binding protein (TBP) recognizes its target sites (TATA boxes) by indirectly reading the DNA sequence through its conformation effects (indirect readout). Here, we explore the molecular mechanisms underlying indirect readout of TATA boxes by TBP by studying the binding of TBP to adenovirus major late promoter (AdMLP) sequence variants, including alterations inside as well as in the sequences flanking the TATA box. We measure here the dissociation kinetics of complexes of TBP with AdMLP targets and, by phase-sensitive assay, the intrinsic bending in the TATA box sequences as well as the bending of the same sequence induced by TBP binding. In these experiments we observe a correlation of the kinetic stability to sequence changes within the TATA recognition elements. Comparison of the kinetic data with structural properties of TATA boxes in known crystalline TBP/TATA box complexes reveals several "signals" for TATA box recognition, which are both on the single base-pair level, as well as larger DNA tracts within the TATA recognition element. The DNA bending induced by TBP on its binding sites is not correlated to the stability of TBP/TATA box complexes. Moreover, we observe a significant influence on the kinetic stability of alteration in the region flanking the TATA box. This effect is limited however to target sites with alternating TA sequences, whereas the AdMLP target, containing an A tract, is not influenced by these changes.     

TBP2 is a substitute for TBP in Xenopus oocyte transcription

Background  

TATA-box-binding protein 2 (TBP2/TRF3) is a vertebrate-specific paralog of TBP that shares with TBP a highly conserved carboxy-terminal domain and the ability to bind the TATA box. TBP2 is highly expressed in oocytes whereas TBP is more abundant in embryos.