linoleic-acid and petroselinic-acid

The beta-oxidation of saturated fatty acids in Saccharomyces cerevisiae is confined exclusively to the peroxisomal compartment of the cell. Processing of mono- and polyunsaturated fatty acids with the double bond at an even position requires, in addition to the basic beta-oxidation machinery, the contribution of the NADPH-dependent enzyme 2,4-dienoyl-CoA reductase. Here we show by biochemical cell fractionation studies that this enzyme is a typical constituent of peroxisomes. As a consequence, the beta-oxidation of mono- and polyunsaturated fatty acids with double bonds at even positions requires stoichiometric amounts of intraperoxisomal NADPH. We suggest that NADP-dependent isocitrate dehydrogenase isoenzymes function in an NADP redox shuttle across the peroxisomal membrane to keep intraperoxisomal NADP reduced. This is based on the finding of a third NADP-dependent isocitrate dehydrogenase isoenzyme, Idp3p, next to the already known mitochondrial and cytosolic isoenzymes, which turned out to be present in the peroxisomal matrix. Our proposal is strongly supported by the observation that peroxisomal Idp3p is essential for growth on the unsaturated fatty acids arachidonic, linoleic and petroselinic acid, which require 2, 4-dienoyl-CoA reductase activity. On the other hand, growth on oleate which does not require 2,4-dienoyl-CoA reductase, and NADPH is completely normal in Deltaidp3 cells.

Topics: Amino Acid Sequence; Arachidonic Acid; Carbon; Cell Division; Chemical Phenomena; Chemistry, Physical; Cytosol; Fatty Acid Desaturases; Fatty Acids; Fatty Acids, Unsaturated; Gene Expression Regulation, Fungal; Genes, Fungal; Hydrogen Bonding; Isocitrate Dehydrogenase; Isomerism; Linoleic Acid; Microbodies; Mitochondria; NADP; Oleic Acid; Oleic Acids; Oxidation-Reduction; Oxidoreductases Acting on CH-CH Group Donors; Peroxisome-Targeting Signal 1 Receptor; Receptors, Cytoplasmic and Nuclear; Saccharomyces cerevisiae; Sequence Homology, Amino Acid; Substrate Specificity

Poly(3-hydroxyalkanoates) (PHAs) were isolated from Pseudomonas putida KT2442 cultivated on petroselenic acid, oleic acid, and linoleic acid to study beta-oxidation of unsaturated fatty acids. Both saturated and unsaturated medium chain length 3-hydroxy fatty acids were found to be constituents of these polymers. With the aid of proton-detected multiple quantum coherence and proton-detected multiple bond coherence NMR spectra the structures of the unsaturated monomers were identified as 3-hydroxy-5-cis-tetradecanoate for PHA produced on oleic acid, and 3-hydroxy-6-cis-dodecanoate and 3-hydroxy-5-cis-8-cis-tetradecadienoate for PHA produced on linoleic acid. The identified structures, which are derived from fatty acid degradation intermediates, indicate a degradation of oleic acid via the enoyl-CoA isomerase-dependent route and a degradation of linoleic acid via the dienoyl-CoA reductase-dependent route.

Topics: Carbon Isotopes; Fatty Acids, Nonesterified; Gas Chromatography-Mass Spectrometry; Hydrogen; Hydroxy Acids; Linoleic Acid; Linoleic Acids; Magnetic Resonance Spectroscopy; Molecular Conformation; Oleic Acid; Oleic Acids; Oxidation-Reduction; Pseudomonas putida