Activity of the Escherichia coli cardiolipin synthase, encoded by cls, increased about 10-fold in the stationary growth phase, while other committedstep enzymes in phospholipid biosynthesis rather decreased. A null cls mutant lost viability to 10−4 of the wild-type cells during the prolonged incubation for 5 days. Cardiolipin was most stable among membrane phospholipids during the incubation. Accordingly, cardiolipin should play a role in survival of the cell and E. coli employs a sophisticated way to form cardiolipin according to need even under non-growing conditions.
