Comparison of the effects of bax-expression in yeast under fermentative and respiratory conditions: investigation of the role of adenine nucleotides carrier and cytochrome c

A new system for bax-expression in yeast has been devised to investigate ba s's effect under fermentative and respiro-fermentative conditions. This has allowed us to show unambiguously that the ability of bax to kill yeast is higher under respiratory conditions than under purely fermentative conditio ns, The extent of killing under respiro-fermentative conditions (non-repres sive sugars) is intermediate. It has been proposed that the two protein ade nine nucleotides carrier (ANC) and cytochrome c play a crucial role in bax- induced cell death. We have investigated the effects of deletion of the gen es encoding the two proteins on the toxicity induced by bax, using this new system. The absence of ANC did not modify bax-induced lethality in any may . Moreover, the absence of cytochrome c also did not prevent bax-induced de ath, Only the kinetics of lethality were altered, All these effects are pre vented by co-expression of bcl-x(L). (C) 1999 Federation of European Bioche mical Societies.