title: Depletion of casein kinase I leads to a NAD(P)(+)/NAD(P)H balance-dependent metabolic adaptation as determined by NMR spectroscopy-metabolomic profile in Kluyveromyces lactis.
abstract: BACKGROUND
  In the Crabtree-negative Kluyveromyces lactis yeast the rag8 mutant is one of nineteen complementation groups constituting the fermentative-deficient model equivalent to the Saccharomyces cerevisiae respiratory petite mutants. These mutants display pleiotropic defects in membrane fatty acids and/or cell walls, osmo-sensitivity and the inability to grow under strictly anaerobic conditions (Rag(-) phenotype). RAG8 is an essential gene coding for the casein kinase I, an evolutionary conserved activity involved in a wide range of cellular processes coordinating morphogenesis and glycolytic flux with glucose/oxygen sensing.
  
  
  METHODS
  A metabolomic approach was performed by NMR spectroscopy to investigate how the broad physiological roles of Rag8, taken as a model for all rag mutants, coordinate cellular responses.
  
  
  RESULTS
  Statistical analysis of metabolomic data showed a significant increase in the level of metabolites in reactions directly involved in the reoxidation of the NAD(P)H in rag8 mutant samples with respect to the wild type ones. We also observed an increased de novo synthesis of nicotinamide adenine dinucleotide. On the contrary, the production of metabolites in pathways leading to the reduction of the cofactors was reduced.
  
  
  CONCLUSIONS
  The changes in metabolite levels in rag8 showed a metabolic adaptation that is determined by the intracellular NAD(P)(+)/NAD(P)H redox balance state.
  
  
  CONCLUSIONS
  The inadequate glycolytic flux of the mutant leads to a reduced/asymmetric distribution of acetyl-CoA to the different cellular compartments with loss of the fatty acid dynamic respiratory/fermentative adaptive balance response.
authors.affiliation: Department of Chemistry, Sapienza University of Rome, Piazzale A. Moro 5, 00185 Rome, Italy. Electronic address: daniela.gorietti@uniroma1.it.
authors.forename: D
authors.initials: D
authors.lastname: Gorietti
authors.forename: E
authors.initials: E
authors.lastname: Zanni
authors.forename: C
authors.initials: C
authors.lastname: Palleschi
authors.forename: M
authors.initials: M
authors.lastname: Delfini
authors.forename: D
authors.initials: D
authors.lastname: Uccelletti
authors.forename: M
authors.initials: M
authors.lastname: Saliola
authors.forename: A
authors.initials: A
authors.lastname: Miccheli
mesh_terms: D047389:Casein Kinase I / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D005947:Glucose / Q000378:metabolism; D006019:Glycolysis; D007716:Kluyveromyces / Q000235:genetics / Q000378:metabolism*; D008055:Lipids / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D055432:Metabolomics; D009249:NADP / Q000378:metabolism*; D010084:Oxidation-Reduction; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D008055:Lipids; D009249:NADP; D047389:Casein Kinase I; D005947:Glucose
keywords: Casein kinase; Metabolomics; NAD(P)(+)/NAD(P)H balance; NMR spectroscopy; Yeast