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A novel suicide substrate for DNA topoisomerases and site-specific recombinases

A B Burgin1, B N Huizenga, H A Nash

  • 1Laboratory of Molecular Biology, National Institute of Mental Health, Bethesda, MD 20892, USA.

Nucleic Acids Research
|August 11, 1995
PubMed

Insights

Modified DNA linkages create effective suicide substrates for enzymes like topoisomerase I and lambda integrase. This breakthrough aids in studying DNA recombination and enzyme inhibition.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Enzymology

Background:

  • DNA topoisomerases and site-specific recombinases are crucial enzymes in cellular processes.
  • Understanding their mechanisms is vital for molecular biology and drug development.

Purpose of the Study:

  • To investigate the utility of 5'-bridging phosphorothioate linkages as suicide substrates.
  • To explore their application in studying lambda integrative recombination and enzyme inhibition.

Main Methods:

  • Synthesis of DNA with 5'-bridging phosphorothioate linkages.
  • Enzymatic assays using calf thymus topoisomerase I and lambda integrase protein (Int).
  • Analysis of cleavage and ligation reactions to assess substrate efficiency.

Main Results:

  • Phosphorothioate linkage replacement creates efficient suicide substrates for topoisomerase I and Int.
  • Enzymes cleave the phosphorothioate linkage, but the generated 5'-sulfhydryl is incompetent for ligation.
  • Irreversible Int-promoted cleavage was used to study lambda integrative recombination.

Conclusions:

  • Phosphorothioate substrates offer advantages over traditional suicide substrates.
  • These substrates are potent tools for inhibiting relevant cellular enzymes.
  • They provide a unique method for studying phosphoryl transfer reactions.

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