Determinants of cytochrome c pro-apoptotic activity. The role of lysine 72 trimethylation.
Cytochrome c released from vertebrate mitochondria engages apoptosis by triggering caspase activation. We previously reported that, whereas cytochromes c from higher eukaryotes can activate caspases in Xenopus egg and mammalian cytosols, iso-1 and iso-2 cytochromes c from the yeast Saccharomyces cerevisiae cannot. Here we examine whether the inactivity of the yeast isoforms is related to a post-translational modification of lysine 72, N-epsilon-trimethylation. This modification was found to abrogate pro-apoptotic activity of metazoan cytochrome c expressed in yeast. However, iso-1 cytochrome c lacking the trimethylation modification also was devoid of pro-apoptotic activity. Thus, both lysine 72 trimethylation and other features of the iso-1 sequence preclude pro-apoptotic activity. Competition studies suggest that the lack of pro-apoptotic activity was associated with a low affinity for Apaf-1. As cytochromes c that lack apoptotic function still support respiration, different mechanisms appear to be involved in the two activities.
Kluck
R M
RM
Division of Cellular Immunology, La Jolla Institute for Allergy and Immunology, San Diego, California 92121, USA.
Ellerby
L M
LM
Ellerby
H M
HM
Naiem
S
S
Yaffe
M P
MP
Margoliash
E
E
Bredesen
D
D
Mauk
A G
AG
Sherman
F
F
Newmeyer
D D
DD
D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis; D003574:Cytochrome c Group / Q000378:metabolism*; D045304:Cytochromes c; D006736:Horses; D008239:Lysine / Q000031:analogs & derivatives / Q000378:metabolism; D008745:Methylation; D008928:Mitochondria / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009865:Oocytes; D010447:Peptide Hydrolases / Q000378:metabolism; D020033:Protein Isoforms; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D014981:Xenopus
C014059:CYC1 protein, S cerevisiae; D003574:Cytochrome c Group; D020033:Protein Isoforms; D029701:Saccharomyces cerevisiae Proteins; C003712:trimethyllysine; D045304:Cytochromes c; D010447:Peptide Hydrolases; C108711:DEVDase; D008239:Lysine