Parsons C A, West S C
Imperial Cancer Research Fund, Clare Hall Laboratories, South Mimms, Herts, UK.
Nucleic Acids Res. 1990 Aug 11;18(15):4377-84. doi: 10.1093/nar/18.15.4377.
T7 endonuclease I binds specifically to four-way junctions in duplex DNA and promotes their resolution into linear duplexes. Under conditions in which the nuclease activity is blocked by the absence of divalent cations, the enzyme forms a distinct protein-DNA complex with the junction, as detected by gel retardation and filter binding assays. The formation of this complex is structure-specific and contrasts with the short-lived binding complexes formed on linear duplex DNA. The binding complex between T7 endonuclease I and a synthetic Holliday junction analog has been probed with hydroxyl radicals. The results indicate that the nuclease binds all four strands about the junction point.
T7核酸内切酶I特异性结合双链DNA中的四链连接，并促进其解旋为线性双链。在二价阳离子缺失导致核酸酶活性受阻的条件下，通过凝胶阻滞和滤膜结合试验检测到该酶与连接点形成独特的蛋白质-DNA复合物。这种复合物的形成具有结构特异性，与在线性双链DNA上形成的短暂结合复合物形成对比。用羟基自由基探测了T7核酸内切酶I与合成霍利迪连接类似物之间的结合复合物。结果表明，核酸酶结合连接点周围的所有四条链。
