Mitochondrial biogenesis in cultured mammalian cells III. Synthesis of mitochondrial phospholipids by subcellular fractions isolated from normal and chloramphenicol-treated BHK-21 cells

Abstract

The capacity of subcellular fractions isolated from chloramphenicol-treated BHK-21 cells to synthesize various mitochondrial phospholipids in vitro was examined. Both mitochondria and microsomes showed the capacity to acylate sn-glycerol 3-phosphate and dihydroxyacetone phosphate to lysophosphatidic acid and acyldihydroxyacetone phosphate and subsequently to phosphatidic acid. Both processes are inhibited in mitochondria from chloramphenicol-treated cells. The synthesis of CDPdiacylglycerol in mitochondria or micro-somes, and the synthesis of phosphatidylinositol and of phosphatidylcholine in microsomes were stimulated in treated cells. A slight stimulation was also observed in the synthesis of phosphatidylglycerol and diphosphatidylglycerol when the labelled precursor was sn-glycerol 3-phosphate in treated cells, although the process was inhibited with labelled glycerol as the precursor. Conversion of phosphatidylglycerol phosphate to phosphatidylglycerol by mitochondria was rate limiting unless the post-microsomal supernatant fraction was added. These results are discussed in regard to the observed inhibition of phospholipid synthesis in BHK-21 cells in culture by chloramphenicol.