Comparison of the ribonucleic acid polymerases from both phases of Histoplasma capsulatum

The three ribonucleic acid (RNA) polymerases (ribonucleoside triphosphate RNA nucleotidyltransferases, EC 2.7.7.6) of the two phases (yeast and mycelial) of the dimorphic fungus Histoplasma capsulatum have been purified and characterized. The corresponding enzymes from the two phases differ in sensitivity to alpha-amanitin, ion and salt requirements, temperature sensitivity, and subunit structure. This is the first case in which such qualitative differences in RNA polymerases have been demonstrated in two growth states of the same organism.