Subunit localizations of zinc(II) in DNA-dependent RNA polymerase from Escherichia coli B.

RNA Polymerase holoenzyme and core enzyme from Escherichia coli B have been shown to contain two zinc ions. Flameless atomic absorption spectroscopy of the isolated core subunits indicated that one zinc ion is localized on the beta subunit and the other is bound on the beta' subunit. Atomic fluorescence spectroscopy showed that prolonged dialysis of the metalloenzyme against 0.01 M o-phenanthroline resulted in the removal of both zinc(II) ions with accompanying loss of enzymatic activity. The activity of the apoenzyme was observed to be completely restored by readdition of zinc(II) and partially restored by cobalt(II).