A novel pairing process promoted by Escherichia coli RecA protein: inverse DNA and RNA strand exchange.
Traditionally, recombination reactions promoted by RecA-like proteins initiate by forming a nucleoprotein filament on a single-stranded DNA (ssDNA), which then pairs with homologous double-stranded DNA (dsDNA). In this paper, we describe a novel pairing process that occurs in an unconventional manner: RecA protein polymerizes along dsDNA to form an active nucleoprotein filament that can pair and exchange strands with homologous ssDNA. Our results demonstrate that this "inverse" reaction is a unique, highly efficient DNA strand exchange reaction that is not due to redistribution of RecA protein from dsDNA to the homologous ssDNA partner. Finally, we demonstrate that the RecA protein-dsDNA filament can also pair and promote strand exchange with ssRNA. This inverse RNA strand exchange reaction is likely responsible for R-loop formation that is required for recombination-dependent DNA replication.
Zaitsev
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EN
Division of Biological Sciences, Sections of Microbiology and of Molecular and Cell Biology, University of California, Davis, California 95616-8665 USA.
Kowalczykowski
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SC
D001483:Base Sequence; D004269:DNA, Bacterial / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D012329:RNA, Bacterial / Q000235:genetics*; D011938:Rec A Recombinases / Q000378:metabolism*
D004269:DNA, Bacterial; D012329:RNA, Bacterial; D011938:Rec A Recombinases