Sythesis and turnover of phospholipids in Escherichia coli cells with inhibited DNA synthesis.

The relative amounts of individual phospholipids are not greatly affected in E. coli B cells inhibited with mitomycin C, nalidixic acid or hydroxyurea. Turnover and synthesis of phospholipids continue in the first 40 minute period of treatment with nalidixic acid and then cease. Arrest of phospholipid synthesis is not coupled with protein synthesis since beta-galactosidase is still induced after cessation of phospholipid metabolism. The cells, washed free of drug, resume growth as well as synthesis and turnover of phospholipids. During the lag phase preceding the renewal of cell division, a decrease in phosphatidylglycerol content and an increase in cardiolipin content are observed. The ratio of these phospholipids is then comparable with that found in normal non-dividing cells. We suggest that the variation in the relative contents of cardiolipin and phosphatidylglycerol might be related to the cell division process.