title: Loss of Cardiolipin Leads to Perturbation of Acetyl-CoA Synthesis.
abstract: Cardiolipin (CL), the signature phospholipid of mitochondrial membranes, plays an important role in mitochondrial processes and bioenergetics. CL is synthesized de novo and undergoes remodeling in the mitochondrial membranes. Perturbation of CL remodeling leads to the rare X-linked genetic disorder Barth syndrome, which shows disparities in clinical presentation. To uncover biochemical modifiers that exacerbate CL deficiency, we carried out a synthetic genetic array screen to identify synthetic lethal interactions with the yeast CL synthase mutant crd1Δ. The results indicated that crd1Δ is synthetically lethal with mutants in pyruvate dehydrogenase (PDH), which catalyzes the conversion of pyruvate to acetyl-CoA. Acetyl-CoA levels were decreased in the mutant. The synthesis of acetyl-CoA depends primarily on the PDH-catalyzed conversion of pyruvate in the mitochondria and on the PDH bypass in the cytosol, which synthesizes acetyl-CoA from acetate. Consistent with perturbation of the PDH bypass, crd1Δ cells grown on acetate as the sole carbon source exhibited decreased growth, decreased acetyl-CoA, and increased intracellular acetate levels resulting from decreased acetyl-CoA synthetase activity. PDH mRNA and protein levels were up-regulated in crd1Δ cells, but PDH enzyme activity was not increased, indicating that PDH up-regulation did not compensate for defects in the PDH bypass. These findings demonstrate for the first time that CL is required for acetyl-CoA synthesis, which is decreased in CL-deficient cells as a result of a defective PDH bypass pathway.
authors.affiliation: From the Department of Biological Sciences, Wayne State University, Detroit, Michigan 48202 and.
authors.forename: Vaishnavi
authors.initials: V
authors.lastname: Raja
authors.affiliation: From the Department of Biological Sciences, Wayne State University, Detroit, Michigan 48202 and.
authors.forename: Amit S
authors.initials: AS
authors.lastname: Joshi
authors.affiliation: From the Department of Biological Sciences, Wayne State University, Detroit, Michigan 48202 and.
authors.forename: Guiling
authors.initials: G
authors.lastname: Li
authors.affiliation: the Department of Pathology, Bioactive Lipids Research Program, Wayne State University School of Medicine, Karmanos Cancer Institute, Detroit, Michigan 48202.
authors.forename: Krishna Rao
authors.initials: KR
authors.lastname: Maddipati
authors.affiliation: From the Department of Biological Sciences, Wayne State University, Detroit, Michigan 48202 and mgreenberg@wayne.edu.
authors.forename: Miriam L
authors.initials: ML
authors.lastname: Greenberg
mesh_terms: D000105:Acetyl Coenzyme A / Q000096:biosynthesis* / Q000235:genetics; D002308:Cardiolipins / Q000235:genetics / Q000378:metabolism*; D003066:Coenzyme A Ligases / Q000235:genetics / Q000378:metabolism*; D019289:Pyruvic Acid / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D002308:Cardiolipins; D029701:Saccharomyces cerevisiae Proteins; D000105:Acetyl Coenzyme A; D019289:Pyruvic Acid; D003066:Coenzyme A Ligases
keywords: acetyl coenzyme A (acetyl-CoA); cardiolipin; energy metabolism; pyruvate dehydrogenase complex (PDC); yeast genetics