PHENOTYPES OF DNAA MUTANTS OF ESCHERICHIA-COLI SENSITIVE TO PHENOTHIAZINE-DERIVATIVES

The activation of DnaA protein by cardiolipin is inhibited by fluphena zine in vitro. We therefore examined the sensitivity of temperature-se nsitive dnaA mutants of Escherichia coli to fluphenazine and other phe nothiazine derivatives. Among the eight dnaA mutants tested, dnaA5, dn aA46 dnaA602, and dnaA604, mutants with mutations in the putative ATP binding site of DnaA protein, showed higher sensitivities to phenothia zine derivatives than did the wild-type strain. The dnaA508 and dnaA16 7 mutants, which have mutations in the N-terminal region of DnaA prote in, 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 p henothiazine derivatives as the wild-type strain. Complementation anal ysis with a plasmid containing the wild-type dnaA gene and phage beta- mediated transduction confirmed that dnaA mutations are responsible fo r these sensitivity phenotypes.