INCREASE IN SYNTHESIS AND STABILITY OF SIGMA(32) ON TREATMENT WITH INHIBITORS OF DNA GYRASE IN ESCHERICHIA-COLI

We report here that in Escherichia coli, the anti-bacterial agent nali dixic acid induces transient stabilization and increased synthesis of sigma(32), accompanied by the induction of heat shock proteins (Dnak a nd GroEL proteins). The induction of heat shock proteins, increased sy nthesis of sigma(32), and stabilization of sigma(32) observed on treat ment of wild-type cells with nalidixic acid were not observed in a nal A26 mutant, a strain that is resistant to nalidixic acid as the result of a mutation in the gyrA gene. Not only oxolinic acid, but also novo biocin, whose targets are the A and B subunits of DNA gyrase, respecti vely, also induced stabilization and increased synthesis of sigma(32). Thus, inhibition of the activity of DNA gyrase may cause stabilizatio n and increased synthesis of sigma(32), resulting in turn in induction of heat shock proteins.