OxyR regulon

OxyR is homologous to the LysR family of bacterial regulatory proteins. As with other members of the LysR family, OxyR is an activator of a regulon of genes and a repressor of its own expression. The mechanism by which the OxyR protein regulates gene expression has been characterized through in vitro assays. Oxidized (but not reduced) OxyR is able to activate transcription; although both forms of OxyR bind to DNA, the two forms interact differently with the promoter sequences. These properties suggest that oxidation of the OxyR protein brings about a conformational change that leads to RNA polymerase activation and that OxyR is the direct sensor and transducer of an oxidative stress signal. This chapter describes the assays that have been used to characterize the OxyR protein. These approaches are applicable to OxyR homologs found in other organisms and to the characterization of additional regulators of oxidative stress responses. These assays are based on the genetic approaches used to characterize the bacterial responses to oxidative stress.