Zinc is associated with the β subunit of DNA-dependent RNA polymerase of Bacillus subtilis

Abstract

The B. subtilis DNA-dependent RNA polymerase holoenzyme and core enzyme each contain about 2 atoms of Zn/molecule. When the dissociated subunits of the enzyme are passed through a blue dextran-Sepharose affinity column, only the .beta. subunit binds to the column. The total Zn content of the enzyme is tightly bound to the .beta. subunit. Dialysis studies suggest that the 2 Zn ions differ in the strength of their association with the .beta. subunit. The presence of Zn in .beta. indicates that this subunit is directly involved in phosphodiester bond formation. The blue dextran-Sepharose column procedure should be useful in future studies of the dissociation and reassociation of the enzyme since the method is rapid and provides excellent recovery of the .beta. subunit and the .alpha. and .beta.'' subunits of the RNA polymerase.