Ring structure of the Escherichia coli DNA-binding protein RdgC associated with recombination and replication fork repair.

Geoffrey S Briggs, Paul A McEwan, Jing Yu, Timothy Moore, Jonas Emsley, Robert G Lloyd

Index: J. Biol. Chem. 282 , 12353-12347, (2007)

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Abstract

The DNA-binding protein, RdgC, is associated with recombination and replication fork repair in Escherichia coli and with the virulence-associated, pilin antigenic variation mediated by RecA and other recombination proteins in Neisseria species. We solved the structure of the E. coli protein and refined it to 2.4A. RdgC crystallizes as a dimer with a head-to-head, tail-to-tail organization forming a ring with a 30 A diameter hole at the center. The protein fold is unique and reminiscent of a horseshoe with twin gates closing the open end. The central hole is lined with positively charged residues and provides a highly plausible DNA binding channel consistent with the nonspecific mode of binding detected in vitro and with the ability of RdgC to modulate RecA function in vivo.