Metabolic Consequences of Limited Phospholipid Synthesis in Escherichia coli

Mutants of Escherichia coli limited in their ability to synthesize phosphatidic acid become severely restricted in their capacities for growth and macromolecular synthesis. This paper reports the effects of partial limitation of phosphatidic acid synthesis in a mutant of E. coli, resulting from an altered sn-glycerol 3-phosphate acyltransferase (EC 2.3.1.15). The alteration in the Km of this enzyme for sn-glycerol 3-phosphate is correlated with intracellular glycerol-P concentration, rates of lipid and macromolecule synthesis, and growth rate. The reduction in the rate of lipid synthesis correlates well with the reduction in macromolecule synthesis and growth rate and suggests a rapid mechanism for coordination of these processes. Inhibition of lipid synthesis causes a specific reduction in the size of the ATP pool and it is postulated that an activation of ATPase by altered membrane environment may be the possible mechanism of ATP reduction and subsequent loss of synthetic capacities.