Manganese-containing superoxide dismutase from the white-rot fungus Phanerochaete chrysosporium: its function, expression and gene structure

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 P. 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.