Monothiol Glutaredoxin Is Essential for Oxidative Stress Protection and Virulence in Pseudomonas aeruginosa

Abstract

Glutaredoxins (Grxs), ubiquitous redox enzymes belonging to the thioredoxin family, catalyze the reduction of thiol-disulfide exchange reactions in a glutathione-dependent manner. A Pseudomonas aeruginosa ΔgrxD mutant exhibited hypersensitivity to oxidative stress-generating agents, such as paraquat (PQ) and cumene hydroperoxide (CHP). In vitro studies showed that P. aeruginosa GrxD acts as an electron donor for organic hydroperoxide resistance enzyme (Ohr) during CHP degradation. The ectopic expression of iron-sulfur cluster ([Fe-S]) carrier proteins, including ErpA, IscA, and NfuA, complements the function of GrxD in the ΔgrxD mutant under PQ toxicity. Constitutively high expression of iscR, nfuA, tpx, and fprB was observed in the ΔgrxD mutant. These results suggest that GrxD functions as a [Fe-S] cluster carrier protein involved in [Fe-S] cluster maturation. Moreover, the ΔgrxD mutant demonstrates attenuated virulence in a Drosophila melanogaster host model. Altogether, the data shed light on the physiological role of GrxD in oxidative stress protection and virulence of the human pathogen, P. aeruginosa.