Phenotypes of dnaA mutants of Escherichia coli sensitive to phenothiazine derivatives

The activation of DnaA protein by cardiolipin is inhibited by fluphenazine in vitro. We therefore examined the sensitivity of temperature-sensitive dnaA mutants of Escherichia coli to fluphenazine and other phenothiazine derivatives. Among the eight dnaA mutants tested, dnaA5, dnaA46 dnaA602, and dnaA604, mutants with mutations in the putative ATP binding site of DnaA protein, showed higher sensitivities to phenothiazine derivatives than did the wild-type strain. The dnaA508 and dnaA167 mutants, which have mutations in the N-terminal region of DnaA protein, also showed higher sensitivities to phenothiazine derivatives. On the other hand, the dnaA204 and dnaA205 mutants, with lesions in the C-terminal region of the DnaA protein, showed the same sensitivity to phenothiazine derivatives as the wild-type strain. Complementation analysis with a plasmid containing the wild-type dnaA gene and phage P1-mediated transduction confirmed that dnaA mutations are responsible for these sensitivity phenotypes.