Intradimerically tethered DNA topoisomerase II is catalytically active in DNA transport

  1. J E Lindsley
  1. Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, 84132, USA.

Abstract

A covalently cross-linked dimer of yeast DNA topoisomerase II was created by fusing the enzyme with the GCN4 leucine zipper followed by two glycines and a cysteine. Upon oxidation of the chimeric protein, a disulfide bond forms between the two carboxyl termini, covalently and intradimerically cross-linking the two protomers. In addition, all nine of the cysteines naturally occurring in topoisomerase II have been changed to alanines in this construct. This cross-linked, cysteine-less topoisomerase II is catalytically active in DNA duplex passage as indicated by ATP-dependent DNA supercoil relaxation and kinetoplast DNA decatenation assays. However, these experiments do not directly distinguish between a "one-gate" and a "two-gate" mechanism for the enzyme.

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  1. PNAS April 2, 1996 vol. 93 no. 7 2975-2980
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