ABSTRACT
The acyl-CoA dehydrogenases (ACDs) are a family of mitochondrial enzymes that oxidize straight chain or branched chain acyl-CoAs in the metabolism of fatty acids or branched chain amino acids. Deficiencies in members of this gene family are important causes of human disease. A cDNA encoding the human precursor for a novel member (gene symbol ACADSB) of the ACD gene family has been isolated and characterized. The open reading frame of 1.3 kb encodes a precursor protein of 431 amino acids, which is processed in vitro to yield a mature protein of 399 amino acids. The cDNA has significant sequence similarity to other members of the acyl-CoA dehydrogenase family, with the greatest homology (38%) to the short chain acyl-CoA dehydrogenase. The cDNA was expressed in eukaryotic (COS) and prokaryotic (Escherichia coli) cells, producing a protein of the expected size, with activity toward the short branched chain acyl-CoA derivatives ((S)-2-methylbutyryl-CoA, isobutyryl-CoA, and 2-methylhexanoyl-CoA), as well as toward the short straight chain acyl-CoAs (butyryl-CoA and hexanoyl-CoA).
Subject(s)
Acyl-CoA Dehydrogenases/genetics , Enzyme Precursors/genetics , Acyl-CoA Dehydrogenase , Acyl-CoA Dehydrogenases/metabolism , Amino Acid Sequence , Animals , Base Sequence , Cell Line , DNA Primers , DNA, Complementary , Enzyme Precursors/metabolism , Humans , Molecular Sequence Data , Substrate SpecificitySubject(s)
Oxidoreductases Acting on CH-NH Group Donors/deficiency , Oxidoreductases Acting on CH-NH Group Donors/metabolism , Skin/enzymology , Vitamin B 12/analogs & derivatives , Cell Line , Cells, Cultured , Enzyme Stability , Female , Fibroblasts/enzymology , Humans , Male , Methylenetetrahydrofolate Reductase (NADPH2) , Vitamin B 12/metabolismABSTRACT
Methylenetetrahydrofolate reductase (MR) deficiency is the most common inborn error of folate metabolism with more than two dozen patients described. The phenotypic spectrum ranges from severe neurological deterioration and early death to asymptomatic adults. Some patients with a severe deficiency of MR have been shown to have thermolabile reductase at 55 degrees C. Since methyltetrahydrofolate, the product of MR, is a methyl donor for methylcobalamin (MeCbl), the cofactor for methionine synthase (MS), we have looked at MeCbl accumulation and MS activity in fibroblasts from 15 patients with MR deficiency. Thermolabile MR was most often but not always seen in later onset disease. MeCbl levels were often lowest in the patients with early onset disease. All but two patients had levels of methionine synthase within the control range.
