The antioxidant protein glutaredoxin 1 is essential for oxidative stress response and pathogenicity ofToxoplasma gondii

Abstract

AbstractGlutaredoxins (Grxs) are ubiquitous antioxidant proteins involved in many molecular processes to protect cells against oxidative damage. Here, we study the roles of Grxs in the pathogenicity ofToxoplasma gondii. We show that Grxs are localized in the mitochondria (Grx1), cytoplasm (Grx2), and apicoplast (Grx3, Grx4), while Grx5 had an undetectable level of expression. We generated Δgrx1‐5mutants ofT. gondiitype I RH and type II Pru strains using CRISPR‐Cas9 system. No significant differences in the infectivity were detected between four Δgrx(grx2‐grx5) strains and their respective wild‐type (WT) strains in vitro or in vivo. Additionally, no differences were detected in the production of reactive oxygen species, total antioxidant capacity, superoxide dismutase activity, and sensitivity to external oxidative stimuli. Interestingly, RHΔgrx1or PruΔgrx1exhibited significant differences in all the investigated aspects compared to the othergrx2‐grx5mutant and WT strains. Transcriptome analysis suggests that deletion ofgrx1altered the expression of genes involved in transport and metabolic pathways, signal transduction, translation, and obsolete oxidation–reduction process. The data support the conclusion thatgrx1supportsT. gondiiresistance to oxidative killing and is essential for the parasite growth in cultured cells and pathogenicity in mice and that the active site CGFS motif was necessary for Grx1 activity.