Increased Activity of Chromatin-bound Ribonucleic Acid Polymerase from Soybean Hypocotyl with Spermidine and High Ionic Strength

Abstract

Optimal activity of chromatin-bound RNA polymerase from soybeans is obtained with 1 mm Mn2−, but only when high ionic strength or polyamines are included in the medium. Such inclusion does not increase the Mg2+ activation of the polymerase, but it does lower the concentration needed for optimum activity from 10 mm to 1 mm. Mg2− activation is inhibited by added Mn2+, and the inhibition is relieved by high ionic strength or spermidine. The RNA polymerase with either cation is almost entirely polymerase I at low and high ionic strength as evidenced by insensitivity to α-amanitin. Treatment of soybean seedlings with 2,4-dichlorophenoxyacetic acid does not change these characteristics; although the activity rises 3- to 4-fold.