An Nrf2/Yap1-like bZIPprotein drives UV-induced oxidative stress response in a Sporobolomyces yeast with evolutionary conservation

Research backgroundUltraviolet radiation represents a major environmental hazard that damages DNA and promotes oxidative stress in all living organisms. In animals, this stress is counteracted by the Nrf2 signalling pathway, while in yeasts such as Saccharomyces cerevisiae, the Yap1 transcription factor coordinates oxidative stress responses. The extent to which these mechanisms are conserved in UV-tolerant yeasts from the Basidiomycota lineage remains poorly understood. Experimental approachWe investigated the stress response of a UV-tolerant Sporobolomyces sp. isolates exposed to long-term ultraviolet-B irradiation. Yeast survival and antioxidant capacity were assessed, followed by proteome-wide quantification of protein expression using tandem mass tag labelling and multidimensional protein identification technology. Proteins were annotated for biological function through gene ontology and pathway analyses to identify stress-related factors and transcriptional regulators. Results and conclusionsThe LEV-2 Sporobolomyces yeast isolate displayed remarkable survival under conditions lethal to S. cerevisiae and showed induction of antioxidant activity during prolonged exposure. Proteomic profiling revealed large-scale adjustments in protein expression, including the upregulation of enzymes involved in antioxidant biosynthesis, enzymatic antioxidants, DNA repair proteins, heat shock proteins, and multiple signalling pathways. Importantly, several basic leucine zipper proteins with similarity to animal Nrf2 and yeast Yap1 were detected, with one factor showing a distinct induction in response to ultraviolet stress. These findings suggest that the oxidative stress response of Sporobolomyces is mediated by conserved regulatory modules comparable to those of both yeasts and animals, highlighting the evolutionary conservation of stress adaptation mechanisms. Novelty and scientific contributionThis work provides the first proteome-level description of the ultraviolet stress response in a Basidiomycota yeast. It demonstrates that bZIP transcription factors drive a complex antioxidant and repair programme in Sporobolomyces, functionally reminiscent of the animal Nrf2 pathway. The results support the view that fundamental oxidative stress responses arose early in eukaryotic evolution and have been preserved across distant fungal and animal lineages.