CRYSTAL-STRUCTURE OF THE REPLICATION TERMINATOR PROTEIN FROM BACILLUS-SUBTILIS AT 2.6-ANGSTROM

The crystal structure of the replication terminator protein (RTP) of B . subtilis has been determined at 2.6 Angstrom resolution. As previous ly suggested by both biochemical and biophysical studies, the molecule exists as a symmetric dimer and is in the alpha+beta protein-folding class. The protein has several uncommon features, including an antipar allel coiled-coil, which serves as the dimerization domain, and both a n alpha-helix and a beta-ribbon suitably positioned to interact with t he major and minor grooves of B-DNA. A site has been identified on the surface of RTP that is biochemically and positionally suitable for in teraction with the replication-specific helicase. Other features of th e structure are consistent with the polar contrahelicase mechanism of the protein. A model of the interaction between RTP and its cognate DN A is presented.