title: A Mechanism for RecA-Promoted Sequence Homology Recognition and Strand Exchange Between Single-Stranded DNA and Duplex DNA, via Triple-Helical Intermediates.
abstract: Abstract   A central function of RecA protein during homologous recombination is to promote sequence recognition and strand exchange between a stretched and unwound single-stranded DNA, to which it is complexed, and a duplex DNA. By studying the properties of DNA under the conditions of deformation imposed by RecA, we propose a model for recognition and strand exchange at the atomic level, via unusual triple-helical intermediates. In this model, association takes place within a stretched and unwound triple helix of a new type, where the invading single strand occupies the minor groove of the duplex in a parallel orientation. Our calculations indicate that strand exchange within this structure is exothermic and results in a triple helix where the third strand interacts in the major groove, the so-called R-DNA triple helix. Preliminary calculations suggest that sequence homology recognition within the triplex of association is partial and that it is completed during strand exchange and product formation.
authors.affiliation: a      Laboratoire de Biochimie Théorique, CNRS UPR 9080   ,  Institut de Biologie Physico-Chimique   ,  13, rue Pierre et Marie Curie ,    75005   ,    Paris   ,    France.
authors.forename: G
authors.initials: G
authors.lastname: Bertucat
authors.forename: R
authors.initials: R
authors.lastname: Lavery
authors.forename: C
authors.initials: C
authors.lastname: Prévost
mesh_terms: D001483:Base Sequence; D004247:DNA / Q000737:chemistry; D004277:DNA, Single-Stranded / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism; D011938:Rec A Recombinases / Q000737:chemistry; D011995:Recombination, Genetic; D017385:Sequence Homology
chemical_list: D004277:DNA, Single-Stranded; D004247:DNA; D011938:Rec A Recombinases