%0 Journal Article %A Mythili, y %A Muniyappa, K. %T Formation of linear plasmid multimers promoted by the phage lambda Red-system in lon mutants of Escherichia coli %D 1993 %J Microbiology, %V 139 %N 10 %P 2387-2397 %@ 1465-2080 %R https://doi.org/10.1099/00221287-139-10-2387 %I Microbiology Society, %X SUMMARY: We report here the formation of plasmid linear multimers promoted by the Red-system of phage lambda using a multicopy plasmid comprised of lambda reda, and red genes, under the control of the lambda cl 857 repressor. Our observations have revealed that the multimerization of plasmid DNA is dependent on the red and recA genes, suggesting a concerted role for these functions in the formation of plasmid multimers. The formation of multimers occurred in a recBCD + sbcB + xthA + lon genetic background at a higher frequency than in the isogenic lon + host cells. The multimers comprised tandem repeats of monomer plasmid DNA. Treatment of purified plasmid DNA with exonuclease III revealed the presence of free double-chain ends in the molecules. Determination of the size of multimeric DNA, by pulse field gel electrophoresis, revealed that the bulk of the DNA was in the range 50240 kb, representing approximately 524 unit lengths of monomeric plasmid DNA. We provide a conceptual framework for Red-system-promoted formation and enhanced accumulation of plasmid linear multimers in lon mutants of E. coli. %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-139-10-2387