Purification and properties of RNA polymerase of phage KB1

Bacteriophage KB1 belongs to group C of Bradely's classification After infection a bacteriophage specific RNA polymerase is induced in infected cells. KB1 RNA polymerase is a stable enzyme and is easily purified to homogeneity in good overall yield. The activity resides in a single polypeptide chain of molecular weight about 90,000. Synthesis of RNA by KB1 RNA polymerase requires a DNA template and Mg++ and like SP6 RNA polymerase, is strongly stimulated by either bovine serum albumin or spermidine. Thiol reactive reagents inhibit the enzyme, suggesting the presence of essential sulfhydryl residues. The enzyme possess a stringent promoter specificity. The KB1 RNA polymerase is also highly active in synthesis of poly(rG) with poly(dI).(dC) as template. My experiments suggest that the catalytic portion of the polymerase can be separated from the RNA polymerase holoenzyme.