A cytochrome c-GFP fusion is not released from mitochondria into the cytoplasm upon expression of Bax in yeast cells.
To study Bax-induced release of cytochrome c in vivo, we have expressed a cytochrome c-GFP (green fluorescent protein) fusion in Saccharomyces cerevisiae cells null for the expression of the endogenous cytochrome. We show here that cytochrome c-GFP is efficiently localised to mitochondria and able to function as an electron carrier between complexes III and IV of the respiratory chain. Strikingly, while natural cytochrome c is released into the cytoplasm upon expression of Bax, the cytochrome c-GFP fusion is not. Nevertheless, cells co-expressing Bax and the cytochrome c-GFP fusion die, indicating that mitochondrial release of cytochrome c is not essential for cell death to occur in yeast. The failure to release cytochrome c-GFP is presumed to arise from increased bulk due to the GFP moiety. We propose that in intact yeast cells, Bax-induced release of cytochrome c into the cytoplasm occurs through a selective pore and not as a consequence of the non-specific breakage of the mitochondrial outer membrane.
Roucou
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X
Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia.
Prescott
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Devenish
R J
RJ
Nagley
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P
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001692:Biological Transport / Q000187:drug effects; D015153:Blotting, Western; D003574:Cytochrome c Group / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D045304:Cytochromes c; D003593:Cytoplasm / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D004318:Doxycycline / Q000494:pharmacology; D004579:Electron Transport; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D015870:Gene Expression / Q000187:drug effects; D049452:Green Fluorescent Proteins; D007425:Intracellular Membranes / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D007834:Lasers; D008164:Luminescent Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D018613:Microscopy, Confocal; D008928:Mitochondria / Q000737:chemistry / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D008970:Molecular Weight; D009761:Nystatin / Q000494:pharmacology; D010539:Permeability / Q000187:drug effects; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D013104:Spheroplasts / Q000166:cytology / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D013997:Time Factors; D051028:bcl-2-Associated X Protein
C014059:CYC1 protein, S cerevisiae; D003574:Cytochrome c Group; D005656:Fungal Proteins; D008164:Luminescent Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D051028:bcl-2-Associated X Protein; D009761:Nystatin; D049452:Green Fluorescent Proteins; D045304:Cytochromes c; D004318:Doxycycline