Influence of compartmental localization on the function of yeast NADP+-specific isocitrate dehydrogenases

被引:17
作者
Contreras-Shannon, V [1 ]
McAlister-Henn, L [1 ]
机构
[1] Univ Texas, Hlth Sci Ctr, Dept Biochem, San Antonio, TX 78229 USA
关键词
isocitrate dehydrogenase; isozymes; Saccharomyces cerevisiae; compartmentation;
D O I
10.1016/j.abb.2003.12.038
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
Three differentially compartmentalized isozymes of isocitrate dehydrogenase (mitochondrial IDP1, cytosolic IDP2, and peroxisomal IDP3) in the yeast Saccharomyces cerevisiae catalyze the NADP+-dependent oxidative decarboxylation of isocitrate to form alpha-ketoglutarate. These enzymes are highly homologous but exhibit some significant differences in physical and kinetic properties. To examine the impact of these differences on physiological function, we exchanged promoters and altered organellar targeting information to obtain expression of IDP2 and IDP3 in mitochondria and of IDPI and IDP3 in the cytosol. Physiological function was assessed as complementation by mislocalized isozymes of defined growth defects of isocitrate dehydrogenase mutant strains. These studies revealed that the IDP isozymes are functionally interchangeable for glutamate synthesis, although mitochondrial localization has a positive impact on this function during fermentative growth. However, IDP2, whether located in mitochondria or in the cytosol, provided the highest level of defense against endogenous or exogenous oxidative stress. (C) 2004 Elsevier Inc. All rights reserved.
引用
收藏
页码:235 / 246
页数:12
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