Soybean ascorbate peroxidase suppresses Bax-induced apoptosis in yeast by inhibiting oxygen radical generation.
Bax, a mammalian proapoptotic member of the Bcl-2 family, can induce cell death when expressed in yeast or plant cells. To identify plant Bax inhibitors, we cotransformed a soybean cDNA library and the Bax gene into yeast cells and screened for expressed genes that prevented Bax-induced apoptosis. From the Bax-inhibiting genes isolated, ascorbate peroxidase (sAPX) was selected for characterization. The transcription of sAPX in plants was specifically induced by oxidative stress. Moreover, overexpression of sAPX partially suppressed the H(2)O(2)-sensitive phenotype of yeast cytosolic catalase T (Deltactt)- and thermosensitive phenotype of cytochrome c peroxidase (Deltaccp)-deleted mutant cells. Examination of reactive oxygen species (ROS) production using the fluorescence method of dihydrorhodamine 123 oxidation revealed that expression of Bax in yeast cells generated ROS, which was greatly reduced by coexpression with sAPX. Our results collectively suggest that sAPX inhibits the generation of ROS by Bax, which in turn suppresses Bax-induced cell death in yeast.
Moon
Haejeong
H
Division of Applied Life Science (BK21 Program), Gyeongsang National University, Jinju 660-701, Korea.
Baek
Dongwon
D
Lee
Boyoung
B
Prasad
D Theertha
DT
Lee
Sang Yeol
SY
Cho
Moo Je
MJ
Lim
Chae Oh
CO
Choi
Myung Suk
MS
Bahk
Jeongdong
J
Kim
Myeong Ok
MO
Hong
Jong Chan
JC
Yun
Dae-Jin
DJ
D017209:Apoptosis; D060387:Ascorbate Peroxidases; D015152:Blotting, Northern; D015153:Blotting, Western; D002374:Catalase / Q000502:physiology; D016923:Cell Death; D003001:Cloning, Molecular; D003578:Cytochrome-c Peroxidase / Q000502:physiology; D018076:DNA, Complementary / Q000378:metabolism; D005434:Flow Cytometry; D015723:Gene Library; D006861:Hydrogen Peroxide / Q000378:metabolism / Q000494:pharmacology; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D018384:Oxidative Stress; D010544:Peroxidases / Q000494:pharmacology*; D010641:Phenotype; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger / Q000378:metabolism; D017382:Reactive Oxygen Species; D012235:Rhodamines / Q000494:pharmacology; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D013025:Glycine max / Q000201:enzymology*; D013696:Temperature; D013997:Time Factors; D014158:Transcription, Genetic; D051028:bcl-2-Associated X Protein
D018076:DNA, Complementary; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D012235:Rhodamines; D051028:bcl-2-Associated X Protein; C058319:dihydrorhodamine 123; D006861:Hydrogen Peroxide; D010544:Peroxidases; D060387:Ascorbate Peroxidases; D003578:Cytochrome-c Peroxidase; D002374:Catalase