Dissociation of the DNA replicase system of bovine lymphocyte nuclei.

Exposure of S-phase nuclei or subnuclear preparations from phytohemagglutinin-stimulated bovine lymphocytes to 0.02 M ATP caused an immediate and almost total loss of their ability to replicate DNA in vitro. Other ribonucleoside and deoxyribonucleoside triphosphates caused a similar inhibition of DNA replication. Levels of ATP which inhibit replication cause the release of DNA polymerases alpha and beta and small pieces of DNA from these nuclei. This release occurs both at 4 and 37 degrees C. The data support the conclusion that high levels of ATP or other nucleoside triphosphates inhibit DNA replication in nuclei by dissolution of the DNA replication complex. The limited success in reconstitution of the DNA replicase complexes is discussed.