title: Demonstration of dimethylnonanoyl-CoA thioesterase activity in rat liver peroxisomes followed by purification and molecular cloning of the thioesterase involved.
abstract: Peroxisomes play an indispensable role in cellular fatty acid oxidation in higher eukaryotes by catalyzing the chain shortening of a distinct set of fatty acids and fatty acid derivatives including pristanic acid (2,6,10,14-tetramethylpentadecanoic acid). Earlier studies have shown that pristanic acid undergoes three cycles of beta-oxidation in peroxisomes to produce 4,8-dimethylnonanoyl-CoA (DMN-CoA) which is then transported to the mitochondria for full oxidation to CO(2) and H(2)O. In principle, this can be done via two different mechanisms in which DMN-CoA is either converted into the corresponding carnitine ester or hydrolyzed to 4,8-dimethylnonanoic acid plus CoASH. The latter pathway can only be operational if peroxisomes contain 4,8-dimethylnonanoyl-CoA thioesterase activity. In this paper we show that rat liver peroxisomes indeed contain 4,8-dimethylnonanoyl-CoA thioesterase activity. We have partially purified the enzyme involved from peroxisomes and identified the protein as the rat ortholog of a known human thioesterase using MALDI-TOF mass spectrometry in combination with the rat EST database. Heterologous expression studies in Escherichia coli established that the enzyme hydrolyzes not only DMN-CoA but also other branched-chain acyl-CoAs as well as straight-chain acyl-CoA-esters. Our data provide convincing evidence for the existence of the second pathway of acyl-CoA transport from peroxisomes to mitochondria by hydrolysis of the CoA-ester in peroxisomes followed by transport of the free acid to mitochondria, reactivation to its CoA-ester, and oxidation to CO(2) and H(2)O. (c)2002 Elsevier Science.
authors.affiliation: Department of Clinical Chemistry, Emma Children's Hospital, Academic Medical Center, University of Amsterdam, Amsterdam, 1100 DE, The Netherlands.
authors.forename: R
authors.initials: R
authors.lastname: Ofman
authors.forename: L
authors.initials: L
authors.lastname: el Mrabet
authors.forename: G
authors.initials: G
authors.lastname: Dacremont
authors.forename: D
authors.initials: D
authors.lastname: Spijer
authors.forename: R J A
authors.initials: RJ
authors.lastname: Wanders
mesh_terms: D018528:ATP-Binding Cassette Transporters; D000818:Animals; D002352:Carrier Proteins / Q000235:genetics; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000737:chemistry / Q000235:genetics; D029968:Escherichia coli Proteins; D020224:Expressed Sequence Tags; D005227:Fatty Acids / Q000378:metabolism; D008099:Liver / Q000737:chemistry / Q000201:enzymology*; D008297:Male; D058619:Maltose-Binding Proteins; D008928:Mitochondria / Q000378:metabolism; D008969:Molecular Sequence Data; D009004:Monosaccharide Transport Proteins; D020675:Peroxisomes / Q000737:chemistry / Q000201:enzymology*; D051381:Rats; D017208:Rats, Wistar; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013347:Subcellular Fractions / Q000737:chemistry / Q000201:enzymology; D013869:Thiolester Hydrolases / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D018528:ATP-Binding Cassette Transporters; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D005227:Fatty Acids; D058619:Maltose-Binding Proteins; D009004:Monosaccharide Transport Proteins; D011993:Recombinant Fusion Proteins; C461599:maltose transport system, E coli; C002844:pristanic acid; C446295:4,8-dimethylnonanoyl-CoA thioesterase; D013869:Thiolester Hydrolases