Type I restriction enzyme with RecA protein promotes illegitimate recombination.
Illegitimate (non-homologous) recombination requires little or no sequence homology between recombining DNAs and has been regarded as being a process distinct from homologous recombination, which requires a long stretch of homology between recombining DNAs. However, we have found a type of illegitimate recombination that requires an interaction between long homologous DNA sequences. It was detected when a plasmid that carried 2-kb-long inverted repeats was subjected to type I (EcoKI) restriction in vivo within a special mutant strain of Escherichia coli. In the present work, we analyzed genetic requirements for this type of illegitimate recombination in well-defined genetic backgrounds. Our analysis demonstrated dependence on RecA function and on the presence of two EcoKI sites on the substrate DNA. These results are in harmony with a model in which EcoKI restriction enzyme attacks an intermediate of homologous recombination to divert it to illegitimate recombination.
Department of Molecular Biology, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan.
Kohji
K
Kusano
Yasuo
Y
Asami
Ayumi
A
Fujita
Masaru
M
Tanokura
Ichizo
I
Kobayashi
D001483:Base Sequence; D004262:DNA Restriction Enzymes / Q000235:genetics / Q000378:metabolism*; D015253:Deoxyribonucleases, Type I Site-Specific / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics; D011938:Rec A Recombinases / Q000235:genetics / Q000378:metabolism*; D011995:Recombination, Genetic; D012091:Repetitive Sequences, Nucleic Acid; D012689:Sequence Homology, Nucleic Acid
D029968:Escherichia coli Proteins; D011938:Rec A Recombinases; D004262:DNA Restriction Enzymes; C089629:endodeoxyribonuclease EcoKI; D015253:Deoxyribonucleases, Type I Site-Specific