title: On the mechanism of RecA-mediated repair of double-strand breaks: no role for four-strand DNA pairing intermediates.
abstract: RecA protein will bind to a gapped duplex DNA molecule and promote a DNA strand exchange with a second homologous linear duplex. A double-strand break in the second duplex is efficiently bypassed in the course of these reactions. We demonstrate that the bypass of double-strand breaks is not explained by a mechanism involving homologous interactions between two duplex DNA molecules, but instead requires the ATP-mediated generation of DNA torsional stress brought about by the action of RecA. The results suggest new pathways for the repair of double-strand breaks and underline the need for new paradigms to explain the alignment of homologous DNAs during genetic recombination.
authors.affiliation: Department of Biochemistry, University of Wisconsin, Madison 53706, USA.
authors.forename: Q
authors.initials: Q
authors.lastname: Shan
authors.forename: M M
authors.initials: MM
authors.lastname: Cox
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D004247:DNA / Q000378:metabolism*; D004260:DNA Repair / Q000502:physiology*; D004269:DNA, Bacterial / Q000235:genetics*; D004277:DNA, Single-Stranded / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D006868:Hydrolysis; D011938:Rec A Recombinases / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004277:DNA, Single-Stranded; D000255:Adenosine Triphosphate; D004247:DNA; D011938:Rec A Recombinases