Role of the C-terminal domain of Bax and Bcl-XL in their localization and function in yeast cells.
It has been suggested that the C-terminal domain of Bcl-2 family members may contain a signal anchor sequence that targets these proteins to the mitochondrial outer membrane. We have investigated the consequence of deleting this domain upon cytochrome c release in yeast strains that coexpress truncated forms of Bax (i.e. BaxA) and Bcl-X(L) (i.e. Bcl-X(L)delta). We find that (i) Bax(delta) is as efficient as full-length Bax in promoting cytochrome c release, but Bcl-x(L)delta has remarkably reduced rescuing ability compared to full-length Bcl-x(L); (ii) full-length Bcl-X(L) protein acts by relocalizing Bax from the mitochondrial fraction to the soluble cytosolic fraction; (iii) Bax undergoes N-terminal cleavage when expressed in yeast, which is prevented by coexpression of Bcl-X(L), suggesting that Bcl-x(L) may mask the cleavage site of Bax through a direct physical interaction of the two proteins.
Priault
M
M
Institut de Biochimie et de Génétique Cellulaires du C.N.R.S., Bordeaux, France.
Camougrand
N
N
Chaudhuri
B
B
Manon
S
S
D003574:Cytochrome c Group / Q000378:metabolism; D008928:Mitochondria / Q000201:enzymology / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000737:chemistry / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000737:chemistry / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000378:metabolism*; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein