Enoyl-CoA hydratase deficiency: identification of a new type of D-bifunctional protein deficiency.
D-bifunctional protein is involved in the peroxisomal beta-oxidation of very long chain fatty acids, branched chain fatty acids and bile acid intermediates. In line with the central role of D-bifunctional protein in the beta-oxidation of these three types of fatty acids, all patients with D-bifunctional protein deficiency so far reported in the literature show elevated levels of very long chain fatty acids, branched chain fatty acids and bile acid inter-mediates. In contrast, we now report two novel patients with D-bifunctional protein deficiency who both have normal levels of bile acid intermediates. Complementation analysis and D-bifunctional protein activity measurements revealed that both patients had an isolated defect in the enoyl-CoA hydratase domain of D-bifunctional protein. Subsequent mutation analysis showed that both patients are homozygous for a missense mutation (N457Y), which is located in the enoyl-CoA hydratase coding part of the D-bifunctional protein gene. Expression of the mutant protein in the yeast Saccharomyces cerevisiae confirmed that the N457Y mutation is the disease-causing mutation. Immunoblot analysis of patient fibroblast homogenates showed that the protein levels of full-length D-bifunctional protein were strongly reduced while the enoyl-CoA hydratase component produced after processing within the peroxisome was undetectable, which indicates that the mutation leads to an unstable protein.
van Grunsven
E G
EG
Department of Pediatrics, University of Amsterdam, Academic Medical Center, The Netherlands.
Mooijer
P A
PA
Aubourg
P
P
Wanders
R J
RJ
D015067:17-Hydroxysteroid Dehydrogenases; D015094:3-Hydroxyacyl CoA Dehydrogenases / Q000172:deficiency / Q000235:genetics; D019943:Amino Acid Substitution; D002478:Cells, Cultured; D004252:DNA Mutational Analysis; D004746:Enoyl-CoA Hydratase / Q000172:deficiency* / Q000235:genetics; D017809:Fatal Outcome; D005816:Genetic Complementation Test; D006801:Humans; D006836:Hydro-Lyases / Q000172:deficiency / Q000235:genetics; D007223:Infant; D008297:Male; D009097:Multienzyme Complexes / Q000172:deficiency / Q000235:genetics; D018901:Peroxisomal Disorders / Q000201:enzymology / Q000235:genetics / Q000473:pathology; D064029:Peroxisomal Multifunctional Protein-2; D017354:Point Mutation
D009097:Multienzyme Complexes; D015067:17-Hydroxysteroid Dehydrogenases; D015094:3-Hydroxyacyl CoA Dehydrogenases; D006836:Hydro-Lyases; D064029:Peroxisomal Multifunctional Protein-2; C104587:HSD17B4 protein, human; D004746:Enoyl-CoA Hydratase