σE-dependent activation of RbpA controls transcription of the furA-katG operon in response to oxidative stress in mycobacteria

Abstract

Mycobacterium tuberculosis adopts various strategies to cope with oxidative stress during infection. Transcriptional regulators, including σ factors, make important contributions to this stress response, but how these proteins cooperate with each other is largely unknown. In this study, the role of RbpA and its cooperation with σ factors in response to oxidative stress are investigated. Knock down expression of rbpA in Mycobacterium smegmatis attenuated bacterial survival in the presence of H2O2. Additionally, transcription of the rbpA gene was induced by H2O2 in a σE-dependent manner. After induction, RbpA interacts with the principal sigma factor, σA, to control the transcription of furA-katG operon, which encodes an H2O2 scavenging enzyme. Moreover, this regulation is responsible for the role of σE in oxidative response because bacterial survival was attenuated and transcription of the furA-katG operon was down-regulated with H2O2 treatment in sigE deletion mutant (ΔsigE), and over-expression of RbpA in ΔsigE strain restored all of these phenotypes. Taken together, our study first illustrated a mechanism for σE in response to oxidative stress through regulation of rbpA transcription. This study was also the first to demonstrate that RbpA is required for the full response to oxidative stress by cooperating with the principal σA.