title: Defect in biosynthesis of mitochondrial acetoacetyl-coenzyme A thiolase in cultured fibroblasts from a boy with 3-ketothiolase deficiency.
abstract: The etiology of 3-ketothiolase deficiency has been attributed to a defect of mitochondrial acetoacetyl-CoA thiolase because the acetoacetyl-CoA thiolase activity in related materials is not activated by K+, a property characteristic for this enzyme. We studied the enzyme protein and the biosynthesis of mitochondrial acetoacetyl-CoA thiolase, using cultured skin fibroblasts from a 5-yr-old boy with 3-ketothiolase deficiency. The following results were obtained. (a) Activation of acetoacetyl-CoA thiolase activity by K+ was nil; (b) The enzyme activity was not affected by treatment with the antibody against mitochondrial acetoacetyl-CoA thiolase; (c) A signal for mitochondrial acetoacetyl-CoA thiolase protein was not detected in the immunoblot analysis; and (d) Pulse-chase experiments of skin fibroblasts, using [35S]methionine, revealed no incorporation of radioactivity into this enzyme. Therefore, fibroblasts from this patient lacked mitochondrial acetoacetyl-CoA thiolase protein due to a defect in its biosynthesis.
mesh_terms: D000101:Acetyl-CoA C-Acetyltransferase / Q000096:biosynthesis* / Q000302:isolation & purification / Q000378:metabolism; D000102:Acetyl-CoA C-Acyltransferase / Q000172:deficiency* / Q000302:isolation & purification / Q000378:metabolism; D000123:Acetyltransferases / Q000096:biosynthesis*; D000217:Acyltransferases / Q000172:deficiency*; D000818:Animals; D002478:Cells, Cultured; D002675:Child, Preschool; D003101:Collodion; D003600:Cytosol / Q000201:enzymology; D004591:Electrophoresis, Polyacrylamide Gel; D004792:Enzyme Precursors / Q000302:isolation & purification; D005347:Fibroblasts / Q000201:enzymology*; D006801:Humans; D007118:Immunoassay; D008297:Male; D008928:Mitochondria / Q000201:enzymology*; D008930:Mitochondria, Liver / Q000201:enzymology; D014176:Protein Biosynthesis; D051381:Rats
chemical_list: D004792:Enzyme Precursors; D003101:Collodion; D000217:Acyltransferases; D000123:Acetyltransferases; D000102:Acetyl-CoA C-Acyltransferase; D000101:Acetyl-CoA C-Acetyltransferase