INDUCED ALPHA-HELIX IN THE VP16 ACTIVATION DOMAIN UPON BINDING TO A HUMAN TAF

Activation domains are functional modules that enable sequence-specifi c DNA binding proteins to stimulate transcription. The structural basi s for the function of activation domains is poorly understood. A combi nation of nuclear magnetic resonance (NMR) and biochemical experiments revealed that the minimal acidic activation domain of the herpes simp lex virus VP16 protein undergoes an induced transition from random coi l to or helix upon binding to its target protein, hTAF(parallel to)31 (a human TFIID TATA box-binding protein-associated factor). Identifica tion of the two hydrophobic residues that make nonpolar contacts sugge sts a general recognition motif of acidic activation domains for hTAF( parallel to)31.