NMR resonance assignments for the nucleotide binding domains of the E. coli clamp loader complex gamma subunit

The E. coli gamma clamp loader is a pentameric complex of delta, delta ' and three gamma subunits that opens and loads beta-clamp proteins onto DNA in an ATP-dependent process essential for efficient DNA replication. ATP binding to the gamma subunits promotes conformational changes that enable the clamp loader to bind and open the ring-shaped beta-clamp homodimer. Here we report the nearly complete backbone and side-chain H-1, C-13 and N-15 NMR resonance assignments of the 242-residue truncated gamma subunit of the clamp loader complex, which includes the N-terminal mini (domain I) and lid (domain II) domains. This construct represents the nucleotide binding module in the clamp loader complex and provides a model system for studies of conformational rearrangements of the clamp loader induced by nucleotide binding.