Evidence for a defect of holocarboxylase synthetase activity in cultured lymphoblasts from a patient with biotin-responsive multiple carboxylase deficiency.
We report here the expression of biotin-responsive multiple carboxylase deficiency in cultured lymphoblasts of a patient whose fibroblasts belong to the bio genetic complementation group. Cultured lymphoblasts from the patient lost propionyl-CoA carboxylase (PCC) and beta-methylcrotonyl-CoA carboxylase (MCC) activities at a faster rate than normal cells when grown in biotin-deficient medium. Recovery of normal PCC and MCC activities, which was independent of protein synthesis, required a 2,500-fold higher biotin concentration than that required by normal lymphoblasts. Holocarboxylase synthetase activity was detected in cell-free extracts through the biotinylation of endogenous apo-PCC in the presence of ATP to form active holo-PCC. While the apo-PCC in extracts of normal biotin-starved lymphoblasts could be activated to 28% of maximal activity, extracts of patient lymphoblasts did not exhibit any ATP and biotin-dependent increase in PCC activity. A normal cell extract, cleared of apocarboxylases by immunoprecipitation, stimulated the PCC activity of a patient cell extract 20-fold. These results indicate that the apoenzyme in bio cells is normal and that the defect lies in the holocarboxylase synthetase.
D001710:Biotin / Q000502:physiology*; D019735:Carbon-Carbon Ligases; D019731:Carbon-Nitrogen Ligases; D002262:Carboxy-Lyases / Q000172:deficiency; D002478:Cells, Cultured; D005260:Female; D005347:Fibroblasts / Q000201:enzymology; D005816:Genetic Complementation Test; D006801:Humans; D066298:In Vitro Techniques; D007223:Infant; D008025:Ligases / Q000172:deficiency*; D008214:Lymphocytes / Q000201:enzymology*; D008661:Metabolism, Inborn Errors / Q000201:enzymology*; D043586:Methylmalonyl-CoA Decarboxylase
D001710:Biotin; D002262:Carboxy-Lyases; D008025:Ligases; D019731:Carbon-Nitrogen Ligases; C023312:holocarboxylase synthetases; D019735:Carbon-Carbon Ligases; C021573:methylcrotonoyl-CoA carboxylase; D043586:Methylmalonyl-CoA Decarboxylase