Ca2+-induced permeability transition can be observed even in yeast mitochondria under optimized experimental conditions.
Yeast mitochondria have generally been believed not to undergo the permeability transition (PT) by the accumulation of Ca(2+) within the mitochondrial matrix, unlike mammalian mitochondria. However, the reason why the yeast PT is not induced by Ca(2+) has remained obscure. In this study, we examined in detail the effects of Ca(2+) on yeast mitochondria under various conditions. As a result, we discovered that the PT could be induced even in yeast mitochondria by externally added Ca(2+) under optimized experimental conditions. The 2 essential parameters for proper observation of the PT-inducing effects of Ca(2+) were the concentrations of the respiratory substrate and that of inorganic phosphate (Pi) in the incubation medium. The yeast mitochondrial PT induced by Ca(2+) was found to be insensitive to cyclosporin A and suppressed in the presence of a high concentration of Pi. Furthermore, when the PT was induced in yeast mitochondria by Ca(2+), the release of cytochrome c from mitochondria was also observed.
Yamada
Akiko
A
School of Dentistry, University of Tokushima, Tokushima 770-8504, Japan.
Yamamoto
Takenori
T
Yoshimura
Yuya
Y
Gouda
Shunichi
S
Kawashima
Satoshi
S
Yamazaki
Naoshi
N
Yamashita
Kikuji
K
Kataoka
Masatoshi
M
Nagata
Toshihiko
T
Terada
Hiroshi
H
Pfeiffer
Douglas R
DR
Shinohara
Yasuo
Y
D002118:Calcium / Q000378:metabolism*; D045304:Cytochromes c / Q000378:metabolism; D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; D015003:Yeasts / Q000378:metabolism*
D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; D045304:Cytochromes c; D002118:Calcium