Cytochrome c peroxidase regulates intracellular reactive oxygen species and methylglyoxal via enzyme activities of erythroascorbate peroxidase and glutathione-related enzymes in Candida albicans

•Ccp1 stimulates EASC and GSH biosynthesis in Candida albicans.•CCP1-deficient cells accumulate ROS in an EASC and GSH level-dependent manner.•CCP1 deficiency induces catalase-peroxidase and superoxide dismutases.•CCP1 disruptants show significant methylglyoxal oxidizing and reducing activity.•CCP1 acts as a negative regulator during both hyphal and budding phases. D-erythroascorbate peroxidase (EAPX1) deficiency causes glutathione deprivation, leading to the accumulation of methylglyoxal and reactive oxygen species (ROS), and especially, induction of cytochrome c peroxidase (Ccp1) in Candida albicans. Nevertheless, reciprocal effects between changes in Ccp1 activity and the antioxidative D-erythroascorbic acid- and glutathione-dependent redox status, which reflects methylglyoxal biosynthesis altering pathophysiology are unclear in eukaryotes. To elucidate the effect of CCP1 expression on EAPX1 and glutathione reductase (Glr1) activity-mediated D-erythroascorbic acid biosynthesis and redox homeostasis, the CCP1 gene was disrupted and overexpressed. First, we demonstrated both glutathione-independent and-dependent metabolite contents and their corresponding gene transcripts and enzyme activities (i.e., Ccp1, catalase-peroxidase [KatG], superoxide dismutase [Sod], Eapx1, and Glr1) in CCP1 mutants. Second, methylglyoxal-oxidizing alcohol dehydrogenase (Adh1) and methylglyoxal-reducing oxidoreductase activity on glycolytic methylglyoxal and pyruvate production and NAD(P)H content were determined in these mutants. Contrary to our expectation, CCP1 disruption (42.19±3.22nmolO2h−1mgwetcell−1) failed to affect cell respiration compared to the wild-type strain (41.62±7.11nmolO2h−1mgwetcell−1) under cyanide treatment, and in contrast to hydrogen peroxide (H2O2) treatment (21.74±1.03nmol O2h−1mgwetcell−1). Additionally, Ccp1 predominantly detoxified H2O2 rather than negligible scavenging activities towards methylglyoxal and other oxidants. CCP1 deficiency stimulated Sod and Adh1 activity but downregulated Glr1, Eapx1, catalase, and peroxidase activity while enhancing KatG, EAPX1, and GLR1 transcription by decreasing glutathione and D-erythroascorbic acid and increasing pyruvate. Noticeably, the ROS-accumulating CCP1-deficient mutant maintained steady-state levels of methylglyoxal, which was revealed to be regulated by methylglyoxal-oxidizing and −reducing activity with drastic changes in NAD(P)H. We confirmed and clarified our results by showing that CCP1/EAPX1 doubl