The gene structure and expression of the antioxidant enzyme manganese-containing superoxide dismutase (MnSOD1) of the white-rot fungus Phanerochaete chrysosporium was characterized. The MnSOD1 protein was purified from liquid cultures of P chrysosporium and the amino acid sequences of four of its tryptic fragments were determined and used to clone a 3.2-kb genomic fragment encompassing the entire gene of MnSOD1. Sequence analysis of the new gene, MnSOD1, revealed more than 80% identity with the MnSOD genes from the white-rot fungi Ganoderma resinaceum, Ganoderma microsporum and Amauroderma rude, forming a clearly discernible cluster. The expression of MnSOD1 was measured as a function of culture age, and a good correlation between transcript level and enzyme activity was observed, with a peak at 72 and 96 h of incubation, respectively. Interestingly, as for R chrysosporium, the only SOD activity detectable in linear cultures of other white-rot fungi tested (Pleurotus florida, Lentinus edodes, Trametes versicolor, Ganoderma lucidum) was cyanide-insensitive SOD activity defined as MnSOD.