Plasmid recombination by the RecBCD pathway of Escherichia coli.
Previously, we demonstrated that exonuclease I-deficient strains of Escherichia coli accumulate high-molecular-weight linear plasmid concatemers when transformed with plasmids carrying the chi sequence (5'- GCTGGTGG-3') (M. M. Zaman and T. C. Boles, J. Bacteriol. 176:5093-5100, 1994). Since high-molecular weight linear DNA is believed to be the natural substrate for RecBCD-mediated recombination during conjugation (A. J. Clark and K. B. Low, p. 155-215, in K. B. Low, ed., The Recombination of Genetic Material, 1988), we analyzed the recombination frequencies of chi+ and chi0 plasmids in sbcB strains. Here, we report that chi sites stimulate plasmid recombination frequency by 16-fold in sbcB strains. Chi-stimulated plasmid recombination is dependent on RecBCD but is independent of RecF pathway genes. The distribution of recombination products suggests that high-molecular-weight linear plasmid DNA is a substrate for RecBCD-mediated recombination. Surprisingly, our data also suggest that chi+ plasmids also recombine by the RecBCD pathway in rec+ sbcB+ cells.
Zaman
M M
MM
Graduate Department of Biochemistry, Brandeis University, Waltham, Massachusetts 02254, USA.
Boles
T C
TC
D001483:Base Sequence; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D043211:Exodeoxyribonuclease V; D005090:Exodeoxyribonucleases / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D010957:Plasmids / Q000235:genetics*; D011995:Recombination, Genetic
D005090:Exodeoxyribonucleases; D043211:Exodeoxyribonuclease V