CRYSTAL-STRUCTURE OF THE YEAST TFIIA TBP/DNA COMPLEX/

The crystal structure of the yeast TFIIA/TBP/TATA promoter complex was solved to 3 angstrom resolution by double-edge multiple wavelength an omalous diffraction from two different species of anomalous scattering elements in the same crystal. The large and small subunits of TFIIA a ssociate intimately to form both domains of a two-domain folding patte rn. TFIIA binds as a heterodimer to the side of the TBP/TATA complex o pposite to the side that binds TFIIB and does not alter the TBP/DNA in teraction. The six-stranded beta-sandwich domain interacts with the am ino-terminal end of TBP through a stereospecific parallel beta-strand interface and with the backbone of the TATA box and the 5'-flanking B- DNA segment. The four-helix-bundle domain projects away from the TBP/T ATA complex, thereby presenting a substantial surface for further prot ein-protein interactions.