DNA breakage and closure by rat liver type 1 topoisomerase: separation of the half-reactions by using a single-stranded DNA substrate.
- 1 May 1981
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 78 (5) , 2883-2887
- https://doi.org/10.1073/pnas.78.5.2883
Abstract
Circular single strands of bacteriophage .phi.X174 DNA are broken by rat liver DNA nicking-closing enzyme (type 1 topoisomerase) in low salt (50 mM KCl) at 37.degree. C, generating linear strands containing covalently bound enzyme. The linear strands can be recircularized in the presence of 10 mM MgCl2 at 24.degree. C and 37.degree. C or 250 mM KCl at 24.degree. C. Recircularization is blocked when the hydroxyl group at the 5'' terminus is phosphorylated. The linears generated by the nicking-closing enzyme can be joined to other DNA fragments containing 5'' hydroxyls, but not 5'' phosphates. The linkage formed in both the intrastrand and interstrand reactions is stable to alkali. Reclosure of broken single strands is presumed to be analogous to the closure step that occurs during nicking and closing cycles on duplex DNA.This publication has 27 references indexed in Scilit:
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