PURIFICATION AND CHARACTERIZATION OF 2 FORMS OF DNA-DEPENDENT ATPASE FROM YEAST

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  • 1 January 1980
    • journal article
    • research article
    • Vol. 255  (10) , 4957-4963
Abstract
Two forms of DNA-dependent ATPase activity were purified from yeast extracts. The 2 ATPases differ from each other in chromatographic properties and heat stabilities but have similar molecular weight and reaction properties. DNA-dependent ATPase I was purified to near homogeneity, while DNA-dependent ATPase II was only partially purified. The 2 ATPases from yeast are related structurally since antiserum raised against ATPase I cross-react against ATPase II. Yeast DNA-dependent ATPase I has a native MW of about 68,000 and consists of a single polypeptide chain. ATPase II also sediments on sucrose gradient as a 68,000-dalton protein. Both yeast DNA-dependent ATPases hydrolyze deoxyribonucleoside triphosphate and ribonucleoside triphosphates to their corresponding nucleoside diphosphates and orthophosphate, but dATP and ATP are preferred substrates. In addition to nucleoside triphosphates, both enzymes require a divalent cation and a polynucleotide for activity. Single-stranded DNA and polydeoxynucleotides are the most effective co-substrates for yeast DNA-dependent ATPases. Addition of yeast DNA-dependent ATPases to DNA synthesis system containing yeast DNA polymerases does not significantly stimulate the rate of DNA synthesis.

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