The major DNA polymerase in cultured plant cells: Partial purification and correlation with cell multiplication.

A DNA polymerase activity was isolated from cells of Oryza sativa L. grown in suspension culture. Molecular mass (∼ 180,000), optimal requirements for pH (neutral), Mg(2+) (5-10 mM), Mn(2+) (1 mM), template preference (activated DNA), lack of activity with native or denatured DNA, and sensitivity to N-ethylmaleimide and ionic strength are similar to those of the vertebrate α-polymerase. Like DNA polymerase α, the DNA polymerase described in this work is the most abundant in proliferating cells of Oryza sativa L., Parthenocissus tricuspidata (Siebold et Zucc.) Planchon, Acer pseudoplatanus L., and Medicago sativa L. and responds to changes in the rate of cell multiplication. We therefore postulate that this α-like DNA polymerase is the replicating enzyme of plant cells.