TERTIARY 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. The secondary structure of Ugi consists of five anti-parallel beta-strands and two alpha-helices (Balasubramanian, S., Beger, R. D., Bennett, S. E., Mosbaugh, D. W., a nd Bolton, P. H. (1995) J. Biol. Chem. 270, 296-303). The tertiary str ucture of Ugi has been deter mined by solution state multidimensional nuclear magnetic resonance. The Ugi structure contains an area of high ly negative electrostatic potential produced by the close proximity of a number of acidic residues. The unfavorable interactions between the se acidic residues are apparently accommodated by the stability of the beta-strands. This negatively charged region is likely to play an imp ortant role in the binding of Ugi to uracil-DNA glycosylase.