Publications

• Human acyl-CoA dehydrogenase-9 plays a novel role in the mitochondrial beta-oxidation of unsaturated fatty acids.

  Ensenauer R., He M., Willard J.M., Goetzman E.S., Corydon T.J., Vandahl B.B., Mohsen A.W., Isaya G., Vockley J.

  Unsaturated fatty acids play an important role in the prevention of human diseases such as diabetes, obesity, cancer, and neurodegeneration. However, their oxidation in vivo by acyl-CoA dehydrogenases (ACADs) that catalyze the first step of each cycle of mitochondrial fatty acid beta-oxidation is ... >> More

  Unsaturated fatty acids play an important role in the prevention of human diseases such as diabetes, obesity, cancer, and neurodegeneration. However, their oxidation in vivo by acyl-CoA dehydrogenases (ACADs) that catalyze the first step of each cycle of mitochondrial fatty acid beta-oxidation is not entirely understood. Recently, a novel ACAD (ACAD-9) of unknown function that is highly homologous to human very-long-chain acyl-CoA dehydrogenase was identified by large-scale random sequencing. To characterize its enzymatic role, we have expressed ACAD-9 in Escherichia coli, purified it, and determined its pattern of substrate utilization. The N terminus of the mature form of the enzyme was identified by in vitro mitochondrial import studies of precursor protein. A 37-amino acid leader peptide was cleaved sequentially by two mitochondrial peptidases to yield a predicted molecular mass of 65 kDa for the mature subunit. Submitochondrial fractionation studies found native ACAD-9 to be associated with the mitochondrial membrane. Gel filtration analysis indicated that, like very-long-chain acyl-CoA dehydrogenase, ACAD-9 is a dimer, in contrast to the other known ACADs, which are tetramers. Purified mature ACAD-9 had maximal activity with long-chain unsaturated acyl-CoAs as substrates (C16:1-, C18:1-, C18:2-, C22:6-CoA). These results suggest a previously unrecognized role for ACAD-9 in the mitochondrial beta-oxidation of long-chain unsaturated fatty acids. Because of the substrate specificity and abundance of ACAD-9 in brain, we speculate that it may play a role in the turnover of lipid membrane unsaturated fatty acids that are essential for membrane integrity and structure. << Less

  J. Biol. Chem. 280:32309-32316(2005) [PubMed] [EuropePMC]

  This publication is cited by 20 other entries.

• Expression and characterization of mutations in human very long-chain acyl-CoA dehydrogenase using a prokaryotic system.

  Goetzman E.S., Wang Y., He M., Mohsen A.W., Ninness B.K., Vockley J.

  Very long-chain acyl-CoA dehydrogenase (VLCAD) catalyzes the first enzymatic step in the mitochondrial beta-oxidation of fatty acids 14-20 carbons in length. More than 100 cases of VLCAD deficiency have been reported with the disease varying from a severe, often fatal neonatal form to a mild adult ... >> More

  Very long-chain acyl-CoA dehydrogenase (VLCAD) catalyzes the first enzymatic step in the mitochondrial beta-oxidation of fatty acids 14-20 carbons in length. More than 100 cases of VLCAD deficiency have been reported with the disease varying from a severe, often fatal neonatal form to a mild adult-onset form. VLCAD is distinguished from matrix-soluble acyl-CoA dehydrogenases by its unique C-terminal domain, homodimeric structure, and localization to the inner mitochondrial membrane. We have for the first time expressed and purified VLCAD using a bacterial system. Recombinant VLCAD had similar biochemical properties to those reported for native VLCAD and the bacterial system was used to study six previously described disease-causing missense mutations including the two most common mild mutations (T220M, V243A), a mutation leading to the severe disease phenotype (R429W), and three mutations in the C-terminal domain (A450P, L462P, and R573W). Of particular interest was the finding that the A450P and L462P bacterial extracts had normal or increased amounts of VLCAD antigen and activity. In the pure form L462P had roughly 30% of wild-type activity while A450P was normal. Using computer modeling both mutations were mapped to a predicted charged surface of VLCAD that we postulate interacts with the mitochondrial membrane. In a membrane pull down assay both mutants showed greatly reduced mitochondrial membrane association, suggesting a mechanism for the disease in these patients. In summary, the bacterial expression system developed here will significantly advance our understanding of both the clinical aspects of VLCAD deficiency and the basic biochemistry of the enzyme. << Less

  Mol. Genet. Metab. 91:138-147(2007) [PubMed] [EuropePMC]

  This publication is cited by 5 other entries.