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The TOM complex is involved in the release of superoxide anion from mitochondria

Małgorzata Budzińska1, Hanna Gałgańska, Andonis Karachitos

  • 1Laboratory of Bioenergetics, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614, Poznań, Poland.

Journal of Bioenergetics and Biomembranes
|August 20, 2009
PubMed

Insights

Mitochondria release superoxide anion (O(2)(*-)), but transport proteins remain unknown. Researchers found the translocase of the outer membrane (TOM) complex is involved in this O(2)(*-) efflux from mitochondria.

Area of Science:

  • Mitochondrial biology
  • Cellular respiration
  • Reactive oxygen species

Background:

  • Superoxide anion (O(2)(*-)) release from mitochondria is documented.
  • The specific proteins facilitating O(2)(*-) transport across the mitochondrial outer membrane, beyond VDAC (voltage dependent anion channel), are not fully identified.

Purpose of the Study:

  • To investigate the role of the translocase of the outer membrane (TOM) complex in the efflux of superoxide anion (O(2)(*-)) from mitochondria.
  • To elucidate the mechanism of O(2)(*-) transport across the mitochondrial outer membrane.

Main Methods:

  • Utilized mitochondria from Saccharomyces cerevisiae, including a VDAC-depleted mutant (Deltapor1) and wild-type isogenic strains.
  • Studied the effect of blocking the TOM complex using a fusion protein (pb(2)-DHFR) on O(2)(*-) release.
  • Correlated O(2)(*-) release levels with Tom40 expression.

Main Results:

  • Blocking the TOM complex with pb(2)-DHFR significantly decreased O(2)(*-) release from mitochondria.
  • This inhibitory effect was more pronounced in the Deltapor1 mutant mitochondria.
  • The observed reduction in O(2)(*-) release correlated with both the overall O(2)(*-) release rates and the expression levels of Tom40.

Conclusions:

  • The translocase of the outer membrane (TOM) complex plays a role in the release of superoxide anion (O(2)(*-)) from mitochondria.
  • The TOM complex, potentially through Tom40, is implicated in mitochondrial O(2)(*-) efflux pathways.

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