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SUMO-1 conjugation to human DNA topoisomerase II isozymes

Y Mao1, S D Desai, L F Liu

  • 1Department of Pharmacology, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA.

The Journal of Biological Chemistry
|June 22, 2000
PubMed

Insights

DNA damage from teniposide causes small ubiquitin-related modifier (SUMO)-1 conjugation to topoisomerase II. This SUMO-1 modification of topoisomerase II also occurs with other stresses, suggesting a direct link to protein changes.

Area of Science:

  • Molecular Biology
  • Biochemistry
  • Cell Biology

Background:

  • Topoisomerase I-mediated DNA damage induces small ubiquitin-related modifier (SUMO)-1 conjugation to topoisomerase I.
  • The role of SUMOylation in topoisomerase II activity and DNA damage response is not fully understood.

Purpose of the Study:

  • To investigate the effect of topoisomerase II-mediated DNA damage on SUMO-1 conjugation.
  • To explore the relationship between topoisomerase II conformation, DNA damage, and SUMO-1 conjugation.

Main Methods:

  • Utilized teniposide (VM-26) and ICRF-193 to induce DNA damage and conformational changes in topoisomerase II.
  • Employed immunological characterization and demonstrated physical interactions to identify SUMO-1 conjugates of topoisomerase II isozymes.
  • Applied oxidative and heat shock stresses to assess nuclear SUMO-1 conjugates.

Main Results:

  • Teniposide-induced DNA damage led to high molecular weight SUMO-1 conjugates of both topoisomerase IIalpha and IIbeta isozymes in HeLa cells.
  • Physical interaction between topoisomerase II and SUMO-1/UBC9 was demonstrated.
  • ICRF-193, without inducing DNA damage, also caused SUMO-1 conjugation to topoisomerase II isozymes.
  • Oxidative and heat shock stresses rapidly increased nuclear SUMO-1 conjugates.

Conclusions:

  • SUMO-1 conjugation is a rapid response to topoisomerase II-mediated DNA damage and also occurs upon conformational changes induced by agents like ICRF-193.
  • These findings suggest that SUMO-1 conjugation to topoisomerases may be a direct consequence of protein conformational changes rather than solely a DNA damage response.
  • Further investigation is needed to elucidate the precise mechanisms and functional implications of topoisomerase II SUMOylation.

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