Bi X, Lyu Y L, Liu L F
Department of Pharmacology UMDNJ-Robert Wood Johnson Medical School, Piscataway 08854, USA.
J Mol Biol. 1995 Apr 14;247(5):890-902. doi: 10.1006/jmbi.1995.0188.
Recombination between directly repeated DNA sequences can occur via both recA-dependent and recA-independent mechanisms. They are differentially affected by the length of the repeat and the distance separating the repeats, respectively. Interestingly, a 623 base-pairs long DNA sequence of the plasmid pBR322 was found to stimulate specifically recA-independent recombination between tandem repeats. Analysis of this stimulating sequence has revealed the following features. (1). It is cis-acting. (2). No specific region of it appears to be essential for the effect. Moreover, a neutral sequence of comparable size was able to substitute for the sequence in influencing recombination. (3). The sequence affects recombination between tandem repeats within the tetA but not the bla gene of pBR322. (4). The sequence exerts its effect in a position-dependent manner. (5). It changes not only the frequency but also the products of recombination. Our results provide an example that recA-independent recombination can be influenced by DNA sequences at a distance.
直接重复DNA序列之间的重组可通过依赖recA和不依赖recA的机制发生。它们分别受到重复序列长度和重复序列间距离的不同影响。有趣的是，发现质粒pBR322中一段623个碱基对长的DNA序列能特异性地刺激串联重复序列之间不依赖recA的重组。对这段刺激序列的分析揭示了以下特征。（1）它是顺式作用的。（2）其似乎没有特定区域对该效应至关重要。此外，一段大小相当的中性序列在影响重组方面能够替代该序列。（3）该序列影响tetA内串联重复序列之间的重组，但不影响pBR322的bla基因内的重组。（4）该序列以位置依赖的方式发挥作用。（5）它不仅改变重组频率，还改变重组产物。我们的结果提供了一个例子，即不依赖recA的重组可受到远距离DNA序列的影响。
