Metabolic effects of mislocalized mitochondrial and peroxisomal citrate synthases in yeast Saccharomyces cerevisiae
Metabolic effects of mislocalized mitochondrial and peroxisomal citrate synthases in yeast Saccharomyces cerevisiae
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DOI：
10.1021/bi991695n
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发表时间：
1999-12-07
期刊：
影响因子：
2.9
通讯作者：
Srere, PA
中科院分区：
文献类型：
--
作者：
Vélot, C;Lebreton, S;Srere, PA
Genes CIT1 and CIT2 from Saccharomyces cerevisiae encode mitochondrial and peroxisomal citrate synthases involved in the Krebs tricarboxylic acid (TCA) cycle and glyoxylate pathway, respectively. A Delta cit1 mutant does not grow on acetate, despite the presence of Cit2p that could, in principle, bypass the resulting block in the TCA cycle. To elucidate this absence of cross-complementation, we have examined the ability of Cit1p to function in the cytosol, and that of Cit2p to function in mitochondria. A cytosolically localized form of Cit1p was also incompetent for restoration of growth of a Delta cit1 strain on acetate, suggesting that mitochondrial localization of Cit1p is essential for its function in the TCA cycle. Cit2p was-able, when mislocalized in mitochondria, to restore a wild-type phenotype in a strain lacking Cit1p. We have purified these two isoenzymes as well as mitochondrial malate dehydrogenase, Mdh1p, and have shown that Cit2p was also able to mimic Cit1p in its in vitro interaction with Mdh1p. Models of Cit1p and Cit2p structures generated on the basis of that of pig citrate synthase indicate very high structural and electrostatic surface potential similarities between the two yeast isozymes. Altogether, these data indicate that metabolic functions may require structural as well as catalytic roles for the enzymes.
