Suppression of metabolic defects of yeast isocitrate dehydrogenase and aconitase mutants by loss of citrate synthase.
Yeast mutants lacking mitochondrial NAD(+)-specific isocitrate dehydrogenase (idhDelta) or aconitase (aco1Delta) were found to share several growth phenotypes as well as patterns of specific protein expression that differed from the parental strain. These shared properties of idhDelta and aco1Delta strains were eliminated or moderated by co-disruption of the CIT1 gene encoding mitochondrial citrate synthase. Gas chromatography/mass spectrometry analyses indicated a particularly dramatic increase in cellular citrate levels in idhDelta and aco1Delta strains, whereas citrate levels were substantially lower in idhDeltacit1Delta and aco1Deltacit1Delta strains. Exogenous addition of citrate to parental strain cultures partially recapitulated effects of high endogenous levels of citrate in idhDelta and aco1Delta strains. Finally, effects of elevated cellular citrate in idhDelta and aco1Delta mutant strains were partially alleviated by addition of iron or by an increase in pH of the growth medium, suggesting that detrimental effects of citrate are due to elevated levels of the ionized form of this metabolite.
Lin
An-Ping
AP
Department of Biochemistry, University of Texas Health Science Center, 7703 Floyd Curl Dr., San Antonio, TX 78229-3900, USA.
Hakala
Kevin W
KW
Weintraub
Susan T
ST
McAlister-Henn
Lee
L
D000154:Aconitate Hydratase / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D002950:Citrate (si)-Synthase / Q000378:metabolism*; D008401:Gas Chromatography-Mass Spectrometry; D007521:Isocitrate Dehydrogenase / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000254:growth & development
D007521:Isocitrate Dehydrogenase; D002950:Citrate (si)-Synthase; D000154:Aconitate Hydratase