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Updated: Jul 11, 2026

The Multifaceted Benefits of Protein Co-expression in Escherichia coli
Published on: February 5, 2015
A novel pairing process promoted by Escherichia coli RecA protein: inverse DNA and RNA strand exchange
E N Zaitsev1, S C Kowalczykowski
1Division of Biological Sciences, Sections of Microbiology and of Molecular and Cell Biology, University of California, Davis, California 95616-8665 USA.
Abstract:
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.
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