An unpaired 3' terminus stimulates recA protein-promoted DNA strand exchange.
In the presence of 100 mM NaCl, the efficient exchange of strands between a circular single strand and an homologous DNA duplex promoted by the recA and single-stranded DNA binding proteins of Escherichia coli requires an unpaired 3' terminus. Of the duplex DNAs tested, only those with 4 unpaired bases at the 3' termini are effective. Without added NaCl, strand exchange proceeds efficiently with all duplex DNA termini examined including a nicked circular duplex. Thus, at approximately physiological salt concentrations, factors in addition to the recA and single-stranded DNA binding proteins are needed to promote efficient strand exchange. One such factor may be a DNA helicase(s).
D001483:Base Sequence; D004247:DNA / Q000378:metabolism*; D004277:DNA, Single-Stranded / Q000378:metabolism; D004926:Escherichia coli; D009690:Nucleic Acid Conformation; D011938:Rec A Recombinases / Q000378:metabolism*; D012965:Sodium Chloride
D004277:DNA, Single-Stranded; D012965:Sodium Chloride; D004247:DNA; D011938:Rec A Recombinases