Synthesis in vitro of precursor‐type carnitine acetyltransferase with messenger RNA from Candida tropicalis

Abstract
Carnitine acetyltransferase was synthesized in vitro in the mRNA-dependent reticulocyte system with mRNA from alkane-grown or propionate-grown cells of C. tropicalis. The protein synthesized in vitro was isolated by immunoprecipitation with antibody against peroxisomal or mitochondrial carnitine acetyltransferase and was compared with peroxisomal carnitine acetyltransferase (MW of subunits, 64,000 and 57,000) and the mitochondrial enzyme (MW of subunits, 64,000 and 52,000) of C. tropicalis by electrophoresis in the presence of sodium dodecyl sulfate. Nascent carnitine acetyltransferase prepared in vitro showed a hetero-oligomeric property, like the peroxisomal and mitochondrial enzymes isolated from C. tropicalis. The MW of the subunits of nascent carnitine acetyltransferase were 71,000 and 57,000, indicating the existence of the precursor form the enzyme. Sucrose density gradient centrifugation of total mRNA showed that these 2 subunit proteins were synthesized with respective mRNA of different sizes. The same precursor-type of carnitine acetyltransferase was obtained with the mRNA from the alkane-grown cells and the propionate-grown cells. A common precursor will probably be post-translationally modified to form the peroxisomal and mitochondrial enzymes.