Solution study of the Escherichia coli DNA polymerase III clamp loader reveals the location of the dynamic ψχ heterodimer

Several X-ray crystal structures of the E. coli core clamp loader containing the five core (delta('), delta, and three truncated gamma) subunits have been determined, but they lack the psi and chi subunits. We report the first solution structure of the complete seven-subunit clamp loader complex using small angle X-ray scattering. This structure not only provides information about the location of the chi and psi subunits but also provides a model of the dynamic nature of the clamp loader complex. (C) 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.