ATPase activity of the UvrA and UvrAB protein complexes of the Escherichia coli UvrABC endonuclease

We have analyzed the ATPase activity exhibited by the UvrABC DNA repair complex. The UvrA protein is an ATPase whose lack of DNA dependence may be related to the ATP induced monomer-dimer transitions. ATP induced dimerization may be responsible for the enhanced DNA binding activity observed in the presence of ATP. Although the UvrA ATPase is not stimulated by dsDNA, such DNA can modulate the UvrA ATPase activity by decreases in Km and Vm and alterations in the Ki for ADP and ATP-gamma-S. The induction of such changes upon binding to DNA may be necessary for cooperative interactions of UvrA with UvrB that result in a DNA stimulated ATPase for the UvrAB protein complex. The UvrAB ATPase displays unique kinetic profiles that are dependent on the structure of the DNA effector. These kinetic changes correlate with changes in footprinting patterns, the stabilization of protein complexes on DNA damage and with the expression of helicase activity.