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Catalytic inhibition of DNA topoisomerase IIalpha by sodium azide

R Ju1, Y Mao, M J Glick

  • 1Department of Molecular Genetics, Ohio State University, Columbus, OH 43210, USA.

Toxicology Letters
|April 28, 2001
PubMed

Insights

Sodium azide catalytically inactivates DNA topoisomerase II (topo II) by interfering with ATP. This study confirms azide inhibits endogenous topo II activity in cells, impacting DNA decatenation and relaxation.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Background:

  • Sodium azide has been previously shown to reduce the clastogenicity of DNA topoisomerase II (topo II) poisons.
  • This suggested azide might act as a catalytic topo II inhibitor, potentially through ATP-dependent mechanisms due to its known interference with ATP production and cellular ATPases.

Purpose of the Study:

  • To verify that sodium azide inhibits endogenous DNA topoisomerase II (topo II) activity in living cells.
  • To elucidate the ATP-sensitive mechanism underlying topo II inactivation by azide.

Main Methods:

  • Assessed the effect of sodium azide on the decatenation and relaxation activities of purified DNA topoisomerase II (topo II).
  • Investigated the impact of azide on topo II/DNA covalent complex formation in cultured mammalian cells.
  • Examined azide's influence on ATP levels and ATPases in cellular contexts.

Main Results:

  • Sodium azide demonstrated a concentration-dependent inhibition of both decatenation and relaxation activities of purified DNA topoisomerase II (topo II).
  • Azide treatment led to a reduction in the formation of topo II/DNA covalent complexes within cells.
  • Evidence suggests azide's inhibitory effect is linked to ATP levels and ATPases.

Conclusions:

  • Sodium azide catalytically inactivates DNA topoisomerase II (topo II).
  • The inactivation mechanism is ATP-sensitive, likely involving interference with the enzyme's ATP-dependent catalytic cycle.
  • Azide's inhibitory action on endogenous topo II in cells was confirmed.

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