Partial Separation of Two Pools of Arginine in Escherichia coli; Preferential Use of Exogenous Rather Than Endogenous Arginine for the Biosynthesis of 1,4-Diaminobutane

Abstract

Abstract The formation of polyamines was measured in Escherichia coli auxotrophs grown in a chemostat on limiting amounts of citrulline-arginine mixtures; the added amino acids were differentially labeled with either 3H or 14C. The 3H:14C ratio in the isolated amines indicated that more amines had been formed from the exogenous arginine than from the arginine formed endogenously from citrulline. In contrast, there was little, or no, preference for either type of arginine in the synthesis of cellular protein. These data suggest that, in E. coli growing under these conditions, exogenous arginine was accessible to arginine decarboxylase before mixing with the arginine that was synthesized endogenously. Thus, one may conclude that exogenous and endogenous arginine are partially separated functionally within the cell.