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

Available data indicate that superoxide anion (O (2) (aEuro cent a') ) is released from mitochondria, but apart from VDAC (voltage dependent anion channel), the proteins involved in its transport across the mitochondrial outer membrane still remain elusive. Using mitochondria of the yeast Saccharomyces cerevisiae mutant depleted of VDAC (Delta por1 mutant) and the isogenic wild type, we studied the role of the TOM complex (translocase of the outer membrane) in the efflux of O (2) (aEuro cent a') from the mitochondria. We found that blocking the TOM complex with the fusion protein pb(2)-DHFR decreased O (2) (aEuro cent a') release, particularly in the case of Delta por1 mitochondria. We also observed that the effect of the TOM complex blockage on O (2) (aEuro cent a') release from mitochondria coincided with the levels of O (2) (aEuro cent a') release as well as with levels of Tom40 expression in the mitochondria. Thus, we conclude that the TOM complex participates in O (2) (aEuro cent a') release from mitochondria.