The mouse gene PDCR encodes a peroxisomal Delta(2),Delta(4)-dienoyl-CoA reductase

Here we describe the identification and characterization of a novel mouse g ene, PDCR, that encodes a peroxisomal Delta(2), Delta(4)-dienoyl-CoA reduct ase, The mouse PDCR cDNA contains an 892-base pair open reading frame and i s predicted to encode a 292-amino acid protein with a deduced molecular mas s of 31,298 Da that terminates in a consensus type-1 peroxisomal targeting signal. Purified recombinant PDCR protein was generated from Escherichia co li and catalyzed the NADPH-dependent reduction of Delta(2)-trans,Delta(4)-t rans-decadienoyl CoA with a specific activity of 20 units/mg, Enzymatic cha racterization followed by high pressure liquid chromatography analysis of t he products revealed that PDCR converted Delta(2)-trans, Delta(4)-trans-dec adienoyl-CoA to a Delta(3)-enoyl-CoA but not to a Delta(2)-enoyl-CoA. Kinet ic analyses demonstrated that PDCR is active on a broad range of Delta(2),D elta(4)-dienoyl-CoAs. Although the observed substrate preference was to Del ta(2)-trans,Delta(4)-trans-decadienoyl-CoA, PDCR was also active on a C-22 substrate with multiple unsaturations, a result consistent with the role of peroxisomes in the oxidation of complex, very long chain, polyunsaturated fatty acids. The presence of a type-1 peroxisomal targeting signal Ala-Lys- Leu-COOH at the C terminus of PDCR suggested that this protein may be perox isomal. We observed that tagged PDCR was efficiently transported to the per oxisome lumen in normal human fibroblasts but not in cells derived from a Z ellweger syndrome patient with a specific defect in peroxisomal matrix prot ein import. We conclude that this protein resides within the peroxisome mat rix and therefore represents the first mammalian peroxisomal Delta(2),Delta (4)-dienoyl-CoA reductase to be characterized at the molecular level.