Lesnik E A, Khalimullina Zh A
Mol Biol (Mosk). 1989 Nov-Dec;23(6):1638-44.
Recombinant plasmid pGC20 containing (GC)9-insert into SmaI site of pUC19 has been used to study the inhibition of cleavage by six restriction endonucleases; KpnI, SacI, EcoRI and also BamHI, XbaI and SalI, due to Z-DNA formation in negatively supercoiled plasmid. The recognition sites of these enzymes were located at different distances on both sides of the (CG)10-sequence. It was shown that the inhibition of the cleavage by KpnI, SacI and EcoRI was decreased in this series as fast as the distance between recognition site and B-Z junction was increased, and no inhibition of cleavage by EcoRI was found. However, such a correlation was not found in the series of BamHI, XbaI and SalI. In contrast with EcoRI the cleavage by SalI was inhibited completely. These results indicate the difference for "sensitivity" of restriction endonucleases to the structural perturbations of DNA associated with B-Z junctions. It seems to depend on features of the enzyme-substrate interaction mechanisms and also on recognition and flanking sequences of DNA. Consequently, experiments with the inhibition of the cleavage by any enzyme can not help to determine the dimension of the region of DNA with altered structure.
含有（GC）9插入到pUC19的SmaI位点的重组质粒pGC20已被用于研究六种限制性内切酶（KpnI、SacI、EcoRI以及BamHI、XbaI和SalI）由于负超螺旋质粒中Z-DNA的形成而对切割的抑制作用。这些酶的识别位点位于（CG）10序列两侧的不同距离处。结果表明，在该系列中，随着识别位点与B-Z连接点之间距离的增加，KpnI、SacI和EcoRI对切割的抑制作用迅速降低，且未发现EcoRI对切割有抑制作用。然而，在BamHI、XbaI和SalI系列中未发现这种相关性。与EcoRI相反，SalI的切割被完全抑制。这些结果表明限制性内切酶对与B-Z连接点相关的DNA结构扰动的“敏感性”存在差异。这似乎取决于酶-底物相互作用机制的特征以及DNA的识别和侧翼序列。因此，用任何一种酶抑制切割的实验都无助于确定结构改变的DNA区域的大小。
