title: Homologous pairing and the formation of nascent synaptic intermediates between regions of duplex DNA by RecA protein.
abstract: The RecA protein from E. coli gains access to duplex DNA, by nucleation from a short single-stranded gap, to form a spiral nucleoprotein filament that is capable of interaction with homologous duplex DNA. The observations described here demonstrate that any part of the nucleoprotein filament, whether it contains single- or double-stranded DNA, is capable of pairing with homologous duplex DNA. Homologous contacts between regions of duplex DNA lead to an increase in the initial rate and final extent of joint molecule formation. The experiments indicate that pairing is facilitated by the formation of nascent synaptic intermediates between duplex DNA sequences. Using chimeric form I DNA, which is incapable of forming an inter-wound or plectonemic joint with the gapped DNA due to the presence of flanking heterologous sequences, we show that these duplex-duplex pairing reactions involve extensive underwinding of the double helix.
authors.affiliation: Imperial Cancer Research Fund, Clare Hall Laboratories, South Mimms, Herts, England.
authors.forename: E C
authors.initials: EC
authors.lastname: Conley
authors.forename: S C
authors.initials: SC
authors.lastname: West
mesh_terms: D001426:Bacterial Proteins / Q000494:pharmacology; D001482:Base Composition; D001483:Base Sequence; D004247:DNA / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli; D008540:Meiosis / Q000187:drug effects*; D011938:Rec A Recombinases / Q000494:pharmacology*; D012689:Sequence Homology, Nucleic Acid; D013573:Synaptonemal Complex / Q000187:drug effects*
chemical_list: D001426:Bacterial Proteins; D004247:DNA; D011938:Rec A Recombinases