Unravelling the Role of Candida albicans Prn1 in the Oxidative Stress Response Through a Proteomic Approach

Abstract

Candida albicans Prn1 is a protein that shares similarities with mammalian Pirin but with an unknown function in the yeast. Orthologues of Prn1 have been identified in other pathogenic fungi but not in Saccharomyces cerevisiae, suggesting a relationship with pathogenesis. Prn1 increase in abundance after H2O2 treatment has been shown previously, thus, in the present work, C. albicans prn1{Delta} mutant and the corresponding wild-type strain SN250 have been treated with H2O2 and their response was studied by quantitative differential proteomics. These assays indicated a lower increase of proteins with oxidoreductase activity after treatment in the prn1{Delta} strain compared to the wild type, as well as an increase in proteasome-activating proteins and a decrease in translation-involved proteins. Accordingly, Prn1 absence, under H2O2 treatment, led to a lower survival rate and a higher percentage of apoptosis, together with higher reactive oxygen species levels and higher proteasome activity. Besides, remarkable differences in the abundance of some transcription factors were observed between the two strains. Mnl1, involved in Prn1 expression, Bas1, Tiff33, and orf19.1150 presented an inverse pattern of expression under H2O2 treatment respect to Nrg1, a Mnl1 antagonist. Interestingly, orf19.4850, a protein orthologue to S. cerevisiae Cub1, has shown to be involved in the response to H2O2 presenting a conserved proteasome function. Under basal conditions, the proteomics results indicate a possible involvement of Prn1 in mitochondrial oxidative stress detoxication. Our experiments confirm Prn1 as a relevant actor in the oxidative response. ImportanceCandida albicans is a human opportunistic pathogen included in the WHO fungal priority pathogens list. The increase in resistant strains necessitates the discovery of new targets for antifungal therapies. Our research sheds light on the important role of the previously uncharacterized C. albicans protein Prn1 during the oxidative stress response. Study of the proteome remodelling under oxidative stress unveils the role of Prn1 in the decreased reactive oxygen species levels and the consequences, such as death by apoptosis and necrosis or cell growth delay. A proteomics approach allowed the identification of several proteins potentially involved in Prn1 activity, such as oxidoreductases and transcription factors. The lack of Prn1 orthologues in Saccharomyces cerevisiae but the presence in other Candida and Aspergillus species implicates this protein in pathogenesis and suggests that it may serve as a candidate for new drug targets.