Directed molecular screening for RecA ATPase inhibitors

The roles of bacterial RecA in the evolution and transmission of antibiotic resistance genes make it an attractive target for inhibition by small molecules. We report two complementary fluorescence-based ATPase assays that were used to screen for inhibitors of RecA. We elected to employ the ADP-linked variation of the assay, with a Z′ factor of 0.83 in 96-well microplates, to assess whether 18 select compounds could inhibit ATP hydrolysis by RecA. The compounds represented five sets of related inhibitor scaffolds, each of which had the potential to cross-inhibit RecA. Although nucleotide analogs, known inhibitors of GHL ATPases, and known protein kinase inhibitors were not active against RecA, we found that three suramin-like agents substantially inhibited RecA’s ATPase activity.