title: Physics of RecA-mediated homologous recognition.
abstract: To accomplish its DNA strand exchange activities, the Escherichia coli protein RecA polymerizes onto DNA to form a stiff helical nucleoprotein filament within which the DNA is extended by 50%. Homology search and recognition occurs between ssDNA within the filament and an external dsDNA molecule. We show that stretching the internal DNA greatly enhances homology recognition by increasing the probability that the homologous regions of a stretched DNA molecule and a parallel, unstretched DNA molecule will be "in register" at some position. We also show that the stretching and stiffness of the filament act together to ensure that initiation of homologous exchange between the substrate DNA molecules at one position precludes initiation of homologous exchange at any other position. This prevents formation of multiple exchange site "topological traps" which would prevent completion of the exchange reaction and resolution of the products.
authors.affiliation: Department of Biomathematics, University of California-Los Angeles, Los Angeles, California 90095-1766, USA.
authors.forename: Kevin
authors.initials: K
authors.lastname: Klapstein
authors.forename: Tom
authors.initials: T
authors.lastname: Chou
authors.forename: Robijn
authors.initials: R
authors.lastname: Bruinsma
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000378:metabolism*; D055592:Biophysical Phenomena; D001703:Biophysics; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D004265:DNA Helicases / Q000737:chemistry / Q000378:metabolism*; D004269:DNA, Bacterial; D004277:DNA, Single-Stranded / Q000737:chemistry; D004926:Escherichia coli / Q000378:metabolism; D007700:Kinetics; D008854:Microscopy, Electron; D008957:Models, Genetic; D015233:Models, Statistical; D008962:Models, Theoretical; D009690:Nucleic Acid Conformation; D009692:Nucleic Acid Heteroduplexes; D011995:Recombination, Genetic
chemical_list: D004269:DNA, Bacterial; D004277:DNA, Single-Stranded; D009692:Nucleic Acid Heteroduplexes; D004247:DNA; D000251:Adenosine Triphosphatases; D004265:DNA Helicases