Transcription activator involved in oxidative stress response, specifically during hyphal growth. Regulates the transcription of genes encoding antioxidant enzymes and components of the cellular thiol-reducing pathways including the mycelium-specific catalase catB (but not the conidia-specific catalase catA), thioredoxin reductase trxB and thioredoxin thiO. Preferentially binds to promoters with the core binding site 5'-TTA[CG]TAA-3'. Activity of the transcription factor is controlled through oxidation of specific cysteine residues resulting in the alteration of its subcellular location. Activation by hydroperoxides induces nuclear accumulation and as a result NapA transcriptional activity 