PURIFICATION AND CHARACTERIZATION OF A 100 KDA DNA-POLYMERASE FROM CAULIFLOWER INFLORESCENCE

A DNA polymerase from cauliflower (Brassica oleracea var. botrytis) in florescence has been purified to near homogeneity through five success ive column chromatographies, and temporally designated cauliflower pol ymerase 1. Cauliflower polymerase 1 is a monopolypeptide with a molecu lar mass of 100 kDa. The enzyme efficiently uses synthetic DNA homopol ymers and moderately activated DNA and a synthetic RNA homopolymer as template-primers. The enzyme is strongly sensitive to dideoxythymidine triphosphate and N-ethylmaleimide, but it is insensitive to aphidicol in. It was stimulated with 250 mM KCl. Its mode of DNA synthesis is hi gh-processive with or without proliferating-cell nuclear antigen. A. 3 ' --> 5' exonuclease activity is associated with cauliflower polymeras e 1. The enzyme is clearly different from cauliflower mitochondrial po lymerase and does not resemble the four different types of wheat DNA p olymerase, designated wheat DNA polymerases A, B, CI and CII. In the p resent paper the role of the enzyme in plant DNA synthesis is discusse d.