Biochemical and genetic analysis of the mitochondrial response of yeast to BAX and BCL-X(L)

Atan Gross, Kirsten Pilcher, Elizabeth Blachly-Dyson, Emy Basso, Jennifer Jockel, Michael C. Bassik, Stanley J. Korsmeyer, Michael Forte

Research output: Contribution to journalArticlepeer-review

145 Scopus citations


The BCL-2 family includes both proapoptotic (e.g., BAX and BAK) and antiapoptotic (e.g., BCL-2 and BCL-X(L)) molecules. The cell death-regulating activity of BCL-2 members appears to depend on their ability to modulate mitochondrial function, which may include regulation of the mitochondrial permeability transition pore (PTP). We examined the function of BAX and BCL- X(L) using genetic and biochemical approaches in budding yeast because studies with yeast suggest that BCL-2 family members act upon highly conserved mitochondrial components. In this study we found that in wild-type yeast, BAX induced hyperpolarization of mitochondria, production of reactive oxygen species, growth arrest, and cell death; however, cytochrome c was not released detectably despite the induction of mitochondrial dysfunction. Coexpression of BCL-X(L) prevented all BAX-mediated responses. We also assessed the function of BCL-X(L) and BAX in the same strain of Saccharomyces cerevisiae with deletions of selected mitochondrial proteins that have been implicated in the function of BCL-2 family members. BAX-induced growth arrest was independent of the tested mitochondrial components, including voltage- dependent anion channel (VDAC), the catalytic β subunit or the δ subunit of the F0F1-ATP synthase, mitochondrial cyclophilin, cytochrome c, and proteins encoded by the mitochondrial genome as revealed by [rho0] cells. In contrast, actual cell killing was dependent upon select mitochondrial components including the β subunit of ATP synthase and mitochondrial genome- encoded proteins but not VDAC. The BCL-X(L) protection from either BAX- induced growth arrest or cell killing proved to be independent of mitochondrial components. Thus, BAX induces two cellular processes in yeast which can each be abrogated by BCL-X(L): cell arrest, which does not require aspects of mitochondrial biochemistry, and cell killing, which does.

Original languageEnglish (US)
Pages (from-to)3125-3136
Number of pages12
JournalMolecular and cellular biology
Issue number9
StatePublished - May 2000
Externally publishedYes

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology


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