Amplification of pSC101 replicons in Escherichia coli during amino acid limitation.

Amino acid starvation of Escherichia coli relA mutants was previously proposed as a method for efficient amplification of plasmids bearing origin of replication derived from ColE1-type plasmids and bacteriophage lambda. Here we demonstrate that plasmids derived from pSC101 replicon can be amplified in E. col relA+ and relA- strains during amino acid limitation but not during amino acid starvation. The amplification efficiency is dependent on temperature (37 degrees C was found to be the optimal temperature). Under optimal conditions, up to 13-fold amplification of a pSC101-derived plasmid may be achieved.