Tracy R B, Kowalczykowski S C
Division of Biological Sciences, University of California at Davis 95616, USA.
Genes Dev. 1996 Aug 1;10(15):1890-903. doi: 10.1101/gad.10.15.1890.
The RecA protein and other DNA strand exchange proteins are characterized by their ability to bind and pair DNA in a sequence-independent manner. In vitro selection experiments demonstrate, unexpectedly, that RecA protein has a preferential affinity for DNA sequences rich in GT composition. Such GT-rich sequences are present in loci that display increased recombinational activity in both eukaryotes and prokaryotes, including the Escherichia coli recombination hotspot, chi (5'-GCTGGTGG-3'). Interestingly, these selected sequences, or chi-containing substrates, display both an enhanced rate and extent of homologous pairing in RecA protein-dependent homologous pairing reactions. Thus, the binding and pairing of DNA by RecA protein is composition-dependent, suggesting that a component of the elevated recombinational activity of chi and increased genomic rearrangements at certain DNA sequences in eukaryotes is contributed by enhanced DNA pairing activity.
RecA蛋白和其他DNA链交换蛋白的特点是能够以序列无关的方式结合和配对DNA。体外选择实验意外地证明，RecA蛋白对富含GT组成的DNA序列具有优先亲和力。这种富含GT的序列存在于真核生物和原核生物中显示出增加的重组活性的基因座中，包括大肠杆菌重组热点chi（5'-GCTGGTGG-3'）。有趣的是，这些选择的序列或含chi的底物在依赖RecA蛋白的同源配对反应中显示出同源配对的速率和程度都有所提高。因此，RecA蛋白对DNA的结合和配对是依赖于组成的，这表明chi的重组活性升高以及真核生物中某些DNA序列处基因组重排增加的一个因素是由增强的DNA配对活性所贡献的。
