SECONDARY STRUCTURE OF URACIL-DNA GLYCOSYLASE INHIBITOR PROTEIN

The Bacillus subtilis bacteriophage PBS2 uracil-DNA glycosylase inhibi tor (Ugi) is an acidic protein of 84 amino acids that inactivates urac il-DNA glycosylase from diverse organisms (Wang, Z., and Mosbaugh, D, W. (1989) J. Biol. Chem. 264, 1163-1171). The secondary structure of U gi has been determined by solution state multidimensional nuclear magn etic resonance, The protein adopts a single well defined structure con sisting of five anti parallel beta-strands and two alpha-helices. Six loop or turn regions were identified that contain approximately one ha lf of the acidic amino acid residues and connect the beta-strands sequ entially to one another, The secondary structure suggests which region s of Ugi may be involved in interactions with uracil-DNA glycosylase.