Regulation of alkyl hydroperoxidase D by AhpdR in the antioxidant enzyme system of Pseudomonas aeruginosa

Abstract

An overabundance of reactive oxygen species (ROS) can disrupt the initial redox equilibrium within cells, resulting in metabolic issues, cellular harm, and potentially death. Pseudomonas aeruginosa is a widespread gram-negative environmental pathogen that causes serious infectious diseases in humans. P. aeruginosa has developed various antioxidant defense systems. In this study, we analyzed the transcription factor AhpdR, encoded by PA0268, which regulates the alkyl hydroperoxide D (AhpD, encoded by PA0269) and is involved in the antioxidant enzyme system of P. aeruginosa. Our experimental results demonstrated that the deletion of PA0268 significantly increase the mRNA transcription levels of various genes of the operon ahpD-PA0270-PA0271 in P. aeruginosa. Moreover, the absence of PA0268 increased AhpD protein expression. Sensitivity assays showed that AhpD was likely to play a role in resisting hydrogen peroxide at low concentrations of hydrogen peroxide, whereas P. aeruginosa seemed to use other more efficient antioxidant strategies to resist higher concentrations of hydrogen peroxide. These findings indicate that P. aeruginosa possesses the transcription factor PA0268, which is involved in alkyl hydroperoxide reductase systems and two-tiered defense pathways against hydrogen peroxide, involving AhpD and KatA. Furthermore, ahpD and PA0270-PA0271 genes may play novel roles in cellular activities against ROS.