Publications

• Human very-long-chain acyl-CoA synthetase: cloning, topography, and relevance to branched-chain fatty acid metabolism.

  Steinberg S.J., Wang S.J., Kim D.G., Mihalik S.J., Watkins P.A.

  Very-long-chain acyl-CoA synthetases (VLCS) activate very-long-chain fatty acids (VLCFA) containing 22 or more carbons to their CoA derivatives. We cloned the human ortholog (hVLCS) of the gene encoding the rat liver enzyme (rVLCS). Both hVLCS and rVLCS contain 620 amino acids, are expressed prima ... >> More

  Very-long-chain acyl-CoA synthetases (VLCS) activate very-long-chain fatty acids (VLCFA) containing 22 or more carbons to their CoA derivatives. We cloned the human ortholog (hVLCS) of the gene encoding the rat liver enzyme (rVLCS). Both hVLCS and rVLCS contain 620 amino acids, are expressed primarily in liver and kidney, and have a potential peroxisome targeting signal 1 (-LKL) at their carboxy termini. When expressed in COS-1 cells, hVLCS activated the VLCFA lignoceric acid (C24:0), a long-chain fatty acid (C16:0), and two branched-chain fatty acids, phytanic acid and pristanic acid. Immunofluorescence and immunoblot studies localized hVLCS to both peroxisomes and endoplasmic reticulum. In peroxisomes of HepG2 cells, hVLCS was topographically oriented facing the matrix and not the cytoplasm. This orientation, coupled with the observation that hVLCS activates branched-chain fatty acids, suggests that hVLCS could play a role in the intraperoxisomal reactivation of pristanic acid produced via alpha-oxidation of phytanic acid. << Less

  Biochem. Biophys. Res. Commun. 257:615-621(1999) [PubMed] [EuropePMC]

  This publication is cited by 3 other entries.

• Phytanic acid activation in rat liver peroxisomes is catalyzed by long-chain acyl-CoA synthetase.

  Watkins P.A., Howard A.E., Gould S.J., Avigan J., Mihalik S.J.

  In Refsum disease, disorders of peroxisome biogenesis, and rhizomelic chondrodysplasia punctata, pathological accumulation of phytanic acid results from impaired alpha-oxidation of this branched-chain fatty acid. Previous studies from this laboratory indicated that activation of phytanic acid to i ... >> More

  In Refsum disease, disorders of peroxisome biogenesis, and rhizomelic chondrodysplasia punctata, pathological accumulation of phytanic acid results from impaired alpha-oxidation of this branched-chain fatty acid. Previous studies from this laboratory indicated that activation of phytanic acid to its CoA derivative precedes its alpha-oxidation in peroxisomes. It was reported that this reaction is catalyzed by a unique phytanoyl-CoA synthetase in human peroxisomes. We wanted to determine whether phytanic acid activation in rats required long-chain acyl-CoA synthetase (LCS), very long-chain acyl-CoA synthetase (VLCS), or a different enzyme. To test directly whether LCS could activate phytanic acid, rat liver cDNA encoding this enzyme was transcribed and translated in vitro. The expressed enzyme had both LCS activity (assayed with palmitic acid, C16: 0) and phytanoyl-CoA synthetase activity; VLCS activity (assayed with lignoceric acid, C24: 0) was not detectable. The ratio of phytanoyl-CoA synthetized activity to palmitoyl-CoA synthetase activity for LCS synthetized in vitro (approximately 205) was higher than that observed in peroxisomes isolated from rat liver (5-10%), suggesting that the expressed enzyme contained sufficient phytanoyl-Coa synthetase activity to account for all activity observed in intact peroxisomes. Further experiments were carried out to verify that phytanic acid was activated by LCS in rat liver peroxisomes. Attempts to separate LCS from phytanoyl-CoA synthetase by chromatography on several matrices were unsuccessful. Preparative isoelectric focusing revealed that phytanoyl-CoA synthetase and LCS had indistinguishable isoelectric points. Phytanoyl-CoA synthetase activity was inhibited by unlabeled palmitic acid but not by lignoceric acid. Heat treatment inactivated both phytanoyl-CoA and palmitoyl-CoA synthetase activities at similar rates. 5,8,11,14-Eicosatetraynoic acid inhibited activation of phytanic acid and palmitic acid in a parallel dose-dependent manner, whereas activation of lignoceric acid was not affected. These data support our conclusion that rat liver LCS, an enzyme known to be present in peroxisomal membranes, has phytanoyl-CoA synthetase activity. << Less

  J. Lipid Res. 37:2288-2295(1996) [PubMed] [EuropePMC]

  This publication is cited by 2 other entries.

• Phytanoyl-CoA ligase activity in rat liver.

  Muralidharan F.N., Muralidharan V.B.

  The enzymatic activation of phytanic acid to phytanoyl-CoA by rat liver preparations was studied using [1-14C] phytanic acid. Subcellular fractionation studies indicated that phytanoyl-CoA ligase activity was present in both mitochondrial and microsomal fractions. The enzyme activity required ATP, ... >> More

  The enzymatic activation of phytanic acid to phytanoyl-CoA by rat liver preparations was studied using [1-14C] phytanic acid. Subcellular fractionation studies indicated that phytanoyl-CoA ligase activity was present in both mitochondrial and microsomal fractions. The enzyme activity required ATP, Mg2+, and CoA in addition to phytanic acid. The activity was ATP specific. Among the various tissues examined, the highest activity was in rat liver followed by heart and kidney. The specific activity was, however, high in liver and adipose tissue. The ligase activity was inhibited by AMP, N-ethylmaleimide and iodoacetic acid. At 10 microM concentration, palmitate or stearate did not inhibit the activity. The kinetics of heat inactivation of phytanoyl-CoA ligase (in the presence of unlabeled palmitate) and palmitoyl-CoA ligase yielded a T1/2 of 3-5 min for the former and 25-35 min for the latter suggesting that phytanoyl-CoA ligase may be different from long chain acyl-CoA ligase. << Less

  Biochem Int 13:123-130(1986) [PubMed] [EuropePMC]