2.1-ANGSTROM RESOLUTION REFINED STRUCTURE OF A TATA BOX-BINDING PROTEIN (TBP)

The three-dimensional structure of a TATA box-binding protein (TBP2) from Arabidopsis thaliana has keen refined at 2.1 Angstrom resolution. TBPs are general eukaryotic transcription factors that participate in initiation of RNA synthesis by all three eukaryotic RNA polymerases. The carboxy-terminal portion of TBP is a unique DNA-binding motif/protein fold, adopting a highly symmetric alpha/beta structure that resembles a molecular saddle with two stirrup-like loops. A ten-stranded, antiparallel beta-sheet provides a concave surface for recognizing class II nuclear gene promoters, while the four amphipathic a-helices on the convex surface are available for interaction with other transcription factors. The myriad interactions of TBP2 with components of the transcription machinery are discussed.