Crystal structure of the replication terminator protein from B. subtilis at 2.6 A.

Abstract

The crystal structure of the replication terminator protein (RTP) of B. subtilis has been determined at 2.6 A resolution. As previously 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 antiparallel coiled-coil, which serves as the dimerization domain, and both an alpha-helix and a beta-ribbon suitably positioned to interact with the major and minor grooves of B-DNA. A site has been identified on the surface of RTP that is biochemically and positionally suitable for interaction with the replication-specific helicase. Other features of the structure are consistent with the polar contrahelicase mechanism of the protein. A model of the interaction between RTP and its cognate DNA is presented.