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Publication Abstract from PubMed

Peroxisomes play an essential role in maintaining fatty acid homeostasis. Although mitochondria are also known to participate in the catabolism of fatty acids via beta-oxidation, differences exist between the peroxisomal and mitochondrial beta-oxidation. Only peroxisomes, but not mitochondrion, can shorten very long chain fatty acids. Here, we describe the crystal structure of a ternary complex of peroxisomal 2, 4 dienoyl CoA reductases (pDCR) with hexadienoyl CoA and NADP, as a prototype for comparison with the mitochondrial DCR (mDCR) to shed light on the differences between the enzymes from the two organelles at the molecular level. Unexpectedly, the structure of pDCR refined to 1.84 A resolution reveals the absence of the tyrosine-serine pair seen in the active site of mDCR, which together with a lysine and an asparagine, have been deemed a hallmark of the SDR family of enzymes. Instead, aspartate hydrogen bonded to the Calpha hydroxyl via a water molecule, seems to perturb the water molecule for protonation of the substrate. Our studies provide the first structural evidence for participation of water in the DCR catalyzed reactions. Biochemical studies and structural analysis suggest that pDCRs can catalyze the shortening of six carbon long substrates in vitro. However, the Km values of pDCR for short chain acyl CoAs are atleast 6 fold higher than those for substrates with 10 or more aliphatic carbons. Unlike mDCR, hinge movements permit pDCR to process very long chain polyunsaturated fatty acids.

Studies on human 2, 4 dienoyl CoA reductase (DCR) sheds new light on peroxisomal beta-oxidation of unsaturated fatty acids.,Hua T, Wu D, Ding W, Wang J, Shaw N, Liu ZJ J Biol Chem. 2012 Jun 28. PMID:22745130^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.