Characterization of Two DNA Polymerases from Cauliflower Inflorescence1

Abstract

Two distinct DNA polymerases, A and B, isolated from a rapidly growing apical tissue of cauliflower (Brassica oleracea var. botrytis) inflorescence have been characterized, and compared with DNA polymerases, α and β, from mouse myeloma. Polymerase-A bears a strong resemblance to polymerase-α from mammalian cells in all properties examined. The character of polymerase-B is also quite similar to polymerase-β of mammalian cells in chromatographic elution properties, template-primer utilization, sensitivity to inhibitors, response to KCl or KP₁ concentration, and other requirements for maximal activity, although it has a higher molecular weight (approx. 78,000) even in the presence of 0.25 M KC1 than polymerase-β (mol. wt. ≦50,000) of mammalian cells. This type of DNA polymerase has not been reported to exist in the plant system.