TATA element recognition by the TATA box-binding protein has been conserved throughout evolution

Cocrystal structures of wild-type TATA box-binding protein (TBP) recognizin g 10 naturally occurring TATA elements have been determined at 2.3-1.8 Angs trom resolution, and compared with our 1.9 Angstrom resolution structure of TBP bound to the Adenovirus major late promoter (AdMLP) TATA box (5'-TATAA AAG-3'). Minor-groove recognition by the saddle-shaped protein induces the same conformational change in each of these oligonucleotides, despite varia tions in promoter sequence that reduce the efficiency of transcription init iation. Three molecular mechanisms explain assembly of diverse TBP-TATA ele ment complexes. (1) T --> A and A --> T transversions leave the minor-groov e face unchanged, permitting formation of TBP-DNA complexes on many A/T-ric h core promoter sequences. (2) Cavities in the interface between TBP and th e minor-groove face of the AdMLP TATA box accommodate the exocyclic NH2 gro ups of G in a TA (C) under bar A box and in a TATAA (G) under bar box. (3) Formation of a C:G Hoogsteen basepair in a TATAAA (C) under bar box elimina tes steric clashes that would be produced by the Watson-Crick base pair. We conclude that the structure of the TBP-TATA box complex found at the heart of the polymerase II (pol II) transcription machinery has remained constan t over the course of evolution, despite variations in TBP and its DNA targe ts.