Yeast lacking superoxide dismutase(s) show elevated levels of "free iron" as measured by whole cell electron paramagnetic resonance

被引:106
作者
Srinivasan, C
Liba, A
Imlay, JA
Valentine, JS
Gralla, EB [1 ]
机构
[1] Univ Calif Los Angeles, Dept Chem & Biochem, Los Angeles, CA 90095 USA
[2] Univ Illinois, Dept Microbiol, Urbana, IL 61801 USA
关键词
D O I
10.1074/jbc.M004239200
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
A current hypothesis explaining the toxicity of superoxide anion in vivo is that it oxidizes exposed [4Fe-4S] clusters in certain vulnerable enzymes causing release of iron and enzyme inactivation. The resulting increased levels of "free iron" catalyze deleterious oxidative reactions in the cell. In this study, we used low temperature Fe(III) electron paramagnetic resonance (EPR) spectroscopy to monitor iron status in whole cells of the unicellular eukaryote, Saccharomyces cerevisiae. The experimental protocol involved treatment of the cells with desferrioxamine, a cell-permeant, Fe(III)-specific chelator, to promote oxidation of all of the "free iron" to the Fe(III) state wherein it is EPR-detectable. Using this method, a small amount of EPR-detectable iron was detected in the wild-type strain, whereas significantly elevated levels were found in strains lacking CuZn-superoxide dismutase (CuZn-SOD) (sod1 Delta), Mn-SOD (sod2 Delta), or both SODs, throughout their growth but particularly in stationary phase, The accumulation was suppressed by expression of wild-type human CuZn-SOD (in the sod1 Delta mutant), by pmr1, a genetic suppressor of the sod Delta mutant phenotype (in the sod1 Delta sod2 Delta double knockout strain), and by anaerobic growth. In wild-type cells, an increase in the EPR-detectable iron pool could be induced by treatment with paraquat, a redox-cycling drug that generates superoxide. Cells that were not pretreated with desferrioxamine had Fe(III) EPR signals that were equally as strong as those from treated cells, indicating that "free iron" accumulated in the ferric form in our strains in vivo. Our results indicate a relationship between superoxide stress and iron handling and support the above hypothesis for superoxide-related oxidative damage.
引用
收藏
页码:29187 / 29192
页数:6
相关论文
共 53 条
[1]  
[Anonymous], 1994, METHODS YEAST GENETI
[2]   Iron and copper transport in yeast and its relevance to human disease [J].
Askwith, C ;
Kaplan, J .
TRENDS IN BIOCHEMICAL SCIENCES, 1998, 23 (04) :135-138
[3]   Regulation of mitochondrial iron accumulation by Yfh1p, a putative homolog of frataxin [J].
Babcock, M ;
deSilva, D ;
Oaks, R ;
DavisKaplan, S ;
Jiralerspong, S ;
Montermini, L ;
Pandolfo, M ;
Kaplan, J .
SCIENCE, 1997, 276 (5319) :1709-1712
[4]  
Bencini A, 1999, INORGANIC ELECTRONIC STRUCTURE AND SPECTROSCOPY, VOL I, P93
[5]   Growth in iron-enriched medium partially compensates Escherichia coli for the lack of manganese and iron superoxide dismutase [J].
Benov, L ;
Fridovich, I .
JOURNAL OF BIOLOGICAL CHEMISTRY, 1998, 273 (17) :10313-10316
[6]  
BEYER W, 1991, PROG NUCLEIC ACID RE, V40, P221
[7]   CCC1 suppresses mitochondrial damage in the yeast model of Friedreich's ataxia by limiting mitochondrial iron accumulation [J].
Chen, OS ;
Kaplan, J .
JOURNAL OF BIOLOGICAL CHEMISTRY, 2000, 275 (11) :7626-7632
[8]   Oxidative stress and iron are implicated in fragmenting vacuoles of Saccharomyces cerevisiae lacking Cu,Zn-superoxide dismutase [J].
Corson, LB ;
Folmer, J ;
Strain, JJ ;
Culotta, VC ;
Cleveland, DW .
JOURNAL OF BIOLOGICAL CHEMISTRY, 1999, 274 (39) :27590-27596
[9]   Identification of a human mitochondrial ABC transporter, the functional orthologue of yeast Atm1p [J].
Csere, P ;
Lill, R ;
Kispal, G .
FEBS LETTERS, 1998, 441 (02) :266-270
[10]   Yeast lacking Cu-Zn superoxide dismutase show altered iron homeostasis - Role of oxidative stress in iron metabolism [J].
De Freitas, JM ;
Liba, A ;
Meneghini, R ;
Valentine, JS ;
Gralla, EB .
JOURNAL OF BIOLOGICAL CHEMISTRY, 2000, 275 (16) :11645-11649