Cysteine dioxygenase involved in sulfite formation from cysteine. Required for keratin degradation and plays an important role in filamentous growth and virulence. L-cysteine + O2 = 3-sulfino-L-alanine + H(+) Binds 1 Fe cation per subunit. Induced by L-cysteine. The thioether cross-link between Cys-113 and Tyr-183 plays a structural role through stabilizing the Fe(2+) ion, and prevents the production of highly damaging free hydroxyl radicals by holding the oxygen radical via hydroxyl hydrogen. Leads to hypersensitivity to L-cysteine. Abolishes the ability to grow on human hair and nails as substrates. Belongs to the cysteine dioxygenase family.