Modulation of peroxide stress response by thiol reagents and the role of a redox sensor-transcription regulator, OxyR in mediating the response in Xanthomonas

Abstract

Pretreatment of Xanthomonas campestris pv. phaseoli with low inducing concentrations of thiol reagents such as N-ethylmaleimide (NEM) and diamide induced resistance to H2O2killing. In addition, these compounds were moderate inducers of peroxide detoxification enzymes such as catalase and alkyl hydroperoxide reductase. For both cases, thiol reagent induced responses required a functional redox sensor/transcription activator oxyR and were absent in an oxyR mutant. By contrast, NEM pretreatment enhanced the killing effects of organic peroxide. The observed Xanthomonas physiological responses to thiol reagent pretreatment, and subsequent challenge with peroxide stress, differed from other bacteria. Copyright (C) 1999 Federation of European Microbiological Societies.