Activation of long chain fatty acids with acyl carrier protein: demonstration of a new enzyme, acyl acyl carrier protein synthetase, in Escherichia coli

A soluble enzyme activity which catalyzes the synthesis of acyl acyl carrier protein from acyl carrier proteins, a long chain fatty acid, and ATP has been demonstrated in E. coli. The reaction requires high concentrations of both Ca⁺⁺ and Mg⁺⁺ for activity, and cleaves ATP to AMP and PP(i). The fatty acyl product has been identified as acyl acyl carrier protein by its solubility, thioester linkage, molecular weight, charge, and biological activity. Several criteria indicate the enzyme is distinct from acyl CoA synthetase. The fatty acid specificity of the enzyme suggests a role of acyl acyl carrier protein synthetase in the incorporation of fatty acids into phospholipid.