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The stretched DNA geometry of recombination and repair nucleoprotein filaments
Author(s) -
Singleton Scott F.,
Xiao Jie
Publication year - 2002
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.10145
Subject(s) - förster resonance energy transfer , homologous recombination , dna , chemistry , holliday junction , nucleoprotein , recombination , protein filament , biophysics , base pair , dna replication , crystallography , fluorescence , biology , physics , biochemistry , gene , quantum mechanics
The RecA protein of Escherichia coli plays essential roles in homologous recombination and restarting stalled DNA replication forks. In vitro, the protein mediates DNA strand exchange between single‐stranded (ssDNA) and homologous double‐stranded DNA (dsDNA) molecules that serves as a model system for the in vivo processes. To date, no high‐resolution structure of the key intermediate, comprised of three DNA strands simultaneously bound to a RecA filament (RecA · tsDNA complex), has been elucidated by classical methods. Here we review the systematic characterization of the helical geometries of the three DNA strands of the RecA · tsDNA complex using fluorescence resonance energy transfer (FRET) under physiologically relevant solution conditions. Measurements of the helical parameters for the RecA · tsDNA complex are consistent with the hypothesis that this complex is a late, poststrand‐exchange intermediate with the outgoing strand shifted by about three base pairs with respect to its registry with the incoming and complementary strands. All three strands in the RecA · tsDNA complex adopt extended and unwound conformations similar to those of RecA‐bound ssDNA and dsDNA. © 2002 Wiley Periodicals, Inc. Biopoly (Nucleic Acid Sci) 61: 145–158, 2002