Sources of NADPH and expression of mammalian NADP+-specific isocitrate dehydrogenases in Saccharomyces cerevisiae

Karyl I. Minard, Gary T. Jennings, Thomas M. Loftus, Dejun Xuan, Lee McAlister-Henn

Research output: Contribution to journalArticlepeer-review

64 Scopus citations


To compare roles of specific enzymes in supply of NADPH for cellular biosynthesis, collections of yeast mutants were constructed by gene disruptions and matings. These mutants include haploid strains containing all possible combinations of deletions in yeast genes encoding three differentially compartmentalized isozymes of NADP+-specific isocitrate dehydrogenase and in the gene encoding glucose-6-phosphate dehydrogenase (Zwf1p). Growth phenotype analyses of the mutants indicate that either cytosolic NADP+-specific isocitrate dehydrogenase (Idp2p) or the hexose monophosphate shunt is essential for growth with fatty acids as carbon sources and for sporulation of diploid strains, a condition associated with high levels of fatty acid synthesis. No new biosynthetic roles were identified for mitochondrial (Idp1p) or peroxisomal (Idp3p) NADP+-specific isocitrate dehydrogenase isozymes. These and other results suggest that several major presumed sources of biosynthetic reducing equivalents are non- essential in yeast cells grown under many cultivation conditions. To develop an in vivo system for analysis of metabolic function, mammalian mitochondrial and cytosolic isozymes of NADP+-specific isocitrate dehydrogenase were expressed in yeast using promoters from the cognate yeast genes. The mammalian mitochondrial isozyme was found to be imported efficiently into yeast mitochondria when fused to the Idp1p targeting sequence and to substitute functionally for Idp1p for production of α-ketoglutarate. The mammalian cytosolic isozyme was found to partition between cytosolic and organellar compartments and to replace functionally Idp2p for production of α-ketoglutarate or for growth on fatty acids in a mutant lacking Zwf1p. The mammalian cytosolic isozyme also functionally substitutes for Idp3p allowing growth on petroselinic acid as a carbon source, suggesting partial localization to peroxisomes and provision of NADPH for β-oxidation of that fatty acid.

Original languageEnglish (US)
Pages (from-to)31486-31493
Number of pages8
JournalJournal of Biological Chemistry
Issue number47
StatePublished - Nov 20 1998

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


Dive into the research topics of 'Sources of NADPH and expression of mammalian NADP+-specific isocitrate dehydrogenases in Saccharomyces cerevisiae'. Together they form a unique fingerprint.

Cite this