Stimulation of DNA polymerase alpha by hypergravity generated by centrifugal acceleration

Gravity alteration is known to influence cell proliferation. Here we tested the effects of hypergravity on the action of DNA polymerase a, one of the DNA replication enzymes in eukaryotes. Hypergravity was produced by horizon tal centrifugal acceleration with a hand-made rotator. The reaction rate of DNA polymerase a in centrifuge tubes increased along with the acceleration up to 4g, when a plateau was reached. In contrast, no stimulation was obse rved with primase, DNA polymerase epsilon, and the E. coli DNA polymerase I Klenow fragment. Kinetic analysis of DNA polymerase a reactions revealed t hat, under high gravity conditions, the K-m value for template DNA decrease d while the V-max stayed constant. In contrast, the centrifugal acceleratio n did not affect the K-m values for deoxyribonucleoside triphosphates. Thes e results suggest that the hypergravity enhances the activity of DNA polyme rase a by increasing the affinity of the enzyme for template DNA. Such enha ncement was more prominent with a low concentration of DNA polymerase a und er low ionic conditions. (C) 2001 Elsevier Science.