A response regulator of the OmpR family is part of the regulatory network controlling the oxidative stress response of Rhodobacter sphaeroides

As a free‐living bacterium Rhodobacter sphaeroides needs to respond to many environmental stresses. Oxidative stress, membrane stress or heat stress induce the ompR‐1 gene encoding a protein of the OmpR family. Overexpression of OmpR‐1 results in increased resistance to organic peroxides and diamide. Our data demonstrate that OmpR‐1 positively affects expression of several sRNAs with an established role in R. sphaeroides stress defences and negatively affects the promoter of the rpoHI gene. The RpoHI sigma factor has a main role in the activation of many stress responses. Thus OmpR‐1 has a balancing effect on the activation of the RpoHI regulon. We present a model with OmpR‐1 as part of a regulatory network controlling stress defences in R. sphaeroides.