Lu M, Guo Q, Studier F W, Kallenbach N R
Department of Chemistry, New York University, New York 10003.
J Biol Chem. 1991 Feb 5;266(4):2531-6.
Endonuclease I is a multipurpose enzyme implicated in the breakdown of host DNA, packaging of phage DNA, and recombination during the lytic cycle of bacteriophage T7. We investigate here some aspects of the substrate requirements for its activity in resolving branched intermediates similar to Holliday junctions (Holliday, R. (1964) Genet. Res. 5, 282-304) that arise in recombination. The enzyme is able to resolve branched substrates containing very short duplex arms: 4 base pairs suffice. It cleaves 5' to the branch, with a distinct preference for the non-crossover strands in Holliday-like model junctions. Ligands that interact strongly with the branch site can inhibit the enzyme, with KI values in the 10-50 microM range.
核酸内切酶I是一种多功能酶，参与宿主DNA的分解、噬菌体DNA的包装以及噬菌体T7裂解周期中的重组过程。我们在此研究了其在解析类似于重组过程中出现的霍利迪连接体（霍利迪，R.（1964年）《遗传研究》5，282 - 304）的分支中间体时的活性底物要求的一些方面。该酶能够解析含有非常短双链臂的分支底物：4个碱基对就足够了。它在分支点的5'端进行切割，对霍利迪样模型连接体中的非交叉链有明显偏好。与分支位点强烈相互作用的配体可以抑制该酶，抑制常数（KI）值在10 - 50微摩尔范围内。
