Abstract
We have shown that rice cells are endowed with a primase which is resistant to α-amanitin and depends on added ATP for its polymerizing activity in a cell-free system in the presence of DNA polymerase I from Escherichia coli.Unlike the animal primase, the bulk (about 60%) of this enzyme is found in the flow through of a phosphocellulose column at 20 mM K-phosphate; the rest is retained by the resin and eluted at 140 mM K-phosphate. Both fractions are free from contaminating α and γ-like DNA polymerase activities and most likely represent a unique enzyme activity.Also at variance with the animal primase, the rice enzyme depends on a γ-like DNA polymerase in a cell-free assay mixture for DNA synthesis initiation when the synthetic oligonucleotide poly(dT) is used as the substrate. However, DNA polymerase α is exclusively required to initiate DNA synthesis when an RNA-primed fd phage DNA is used as the template.This induces us to propose that DNA polymerase α is sufficient to initiate nuclear DNA synthesis in plant cells, as has already been shown in the case of animals cells.
Published Version
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