Wang Y H, Bortner C D, Griffith J
Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill 27599-7295.
J Biol Chem. 1993 Aug 15;268(23):17571-7.
Studies from several laboratories have demonstrated that RecA protein can recognize a variety of perturbations in the DNA helix. Here, using a nitrocellulose filter binding assay, it was observed that RecA bound to bulge-containing DNAs more effectively than non-bulged DNA. The degree of binding of RecA protein to bulged DNA was dependent on the conformation of the bulged bases and the kinking angles produced by the bulges as determined by the type and number of bases in the bulge. Although a single base mismatch does not kink DNA, RecA protein showed preferential binding to DNAs containing certain single base mismatches. An A.C mismatch flanked by A.T base pairs in a 28-base pair (bp) DNA facilitated the binding of RecA protein to the same high level as when the 28-bp DNA contained a 4-base cytosine bulge. Chemical probing techniques were used to examine the structure of DNA within the RecA filament. It was found that upon binding of RecA protein, the DNA helix becomes accessible over at least 14 bp, and the degree of sensitivity agrees with the binding efficiency of RecA protein.
来自多个实验室的研究表明，RecA蛋白能够识别DNA螺旋中的多种扰动。在此，通过硝酸纤维素滤膜结合试验观察到，RecA与含有凸起的DNA的结合比与无凸起的DNA更有效。RecA蛋白与凸起DNA的结合程度取决于凸起碱基的构象以及由凸起中碱基的类型和数量所决定的凸起产生的扭结角度。虽然单个碱基错配不会使DNA发生扭结，但RecA蛋白显示出对含有某些单个碱基错配的DNA具有优先结合性。在一个28个碱基对（bp）的DNA中，由A.T碱基对侧翼包围的A.C错配促进RecA蛋白的结合，使其达到与该28 bp DNA含有一个4碱基胞嘧啶凸起时相同的高水平。化学探测技术被用于检测RecA丝内DNA的结构。结果发现，在RecA蛋白结合后，DNA螺旋在至少14 bp的范围内变得可及，并且敏感程度与RecA蛋白的结合效率一致。
