The multiple roles for ATP in the Escherichia coli UvrABC endonuclease-catalyzed incision reaction.

The biochemical properties of the Escherichia coli UvrA tandem ATPase site mutants in nucleotide excision repair have been studied. In these and earlier studies it was found that ATP binding is required for protein-protein and nucleoprotein association reactions, whereas the dissociation reactions are driven by the hydrolysis of ATP. The self-association of UvrA to form the reactive dimeric species UvrA2 is driven by nucleotide binding, but its dissociation from DNA requires ATP hydrolysis. Similarly, ATP binding drives those allosteric changes in DNA topology during UvrA2-nucleoprotein formation (Oh, E.Y., and Grossman, L. (1986) Nucleic Acids Res. 14, 8557-8571). The manifestation of the UvrB-associated cryptic ATPase requires UvrA and DNA in a helicase-catalyzed supercoiling reaction. The UvrA2B helicase activity requires ATP hydrolysis by the C-terminal ATPase site of UvrA in addition to UvrB. ATP hydrolysis by the C-terminal ATPase site of UvrA also participates in the localization of damaged sites contributing to the formation of damage-specific high affinity nucleoprotein complexes. The levels of complementation to UV survival by the ATPase site mutants of UvrA (Thiagalingam, S., and Grossman, L. (1991) J. Biol. Chem. 266, 11395-11403) correspond to its ability to self-bind and translocate in combination with the UvrB subunit in its search for damaged sites during the preincision mode of nucleotide excision.