JBC, Vol. 250, Issue 2, 479-487, Jan, 1975
Deoxyribonucleic acid-dependent ribonucleic acid polymerases in the dimorphic fungus Mucor rouxii
H. A. Young and H. R. Whiteley
Three forms of DNA-dependent RNA polymerase have been separated by
chromatography of extracts of yeast-like cells and mycelium of the
dimorphic fungus Mucor rouxii. Each of the three eznymes has been purified
by means of protamine sulfate precipitation, ion exchange chromatography,
affinity chromatography, and velocity sedimentation. Electrophoresis under
denaturing conditions showed differences in the subunit compositions of all
three purified enzymes. The properties of the enzymes from M. rouxii were
similar to those of polymerases from other eukaryotic organisms. Denatured
DNA was a better template than native DNA for all three enzymes but each
enzyme had a distinct pattern of activities with different templates.
Enzymes I and III displayed optimal activity with Mn-2gs the divalent
cation and were stimulated significantly by Kcl and (NH4)2S04. Enzyme II
had a greater activity with Mg-2gnd was only slightly stimulated by KCl and
(NH4)2SO4. None of the enzymes were inhibited by cycloheximide or by
rifampicin: all were inhibited by actinomycin C and rifampin AF/018: only
enzyme II was inhibited by alpha-amanitin. No differences could be found in
the properties of the same enzymes isolated from yeast-like cells or
mycelium.