Escherichia coli K-12 Mutants Altered in the Transport Systems for Oligo- and Dipeptides

Abstract

Two mutants of Escherichia coli K-12, defective in the oligopeptide and dipeptide transport system, are described. A mutant defective in the oligopeptide transport system ( opp-1 ) was isolated as resistant to the inhibitory action of triornithine; this mutant is also resistant to glycylglycylvaline and does not concentrate 14 C-glycylglycylglycine, although it is still as sensitive as the parental strain to glycylvaline and valine. Starting from the opp-1 strain, a mutant defective also in the dipeptide transport system ( dpp-1 ) was isolated; this mutant is resistant to the inhibitory action of glycylvaline, valylleucine, and leucylvaline and does not concentrate 14 C-glycylglycine, although it is still as sensitive as the parental strain to valine. The apparent kinetic constants for oligopeptide and dipeptide transport were measured. The opp marker is co-transducible with trp at 27 min on the E. coli genetic map. The dpp locus is separated from opp and is located between proC (10 min) and opp .