Institute of Biotechnology, Vilnius University, Vilnius, Lithuania.
FEBS Lett. 2012 Sep 21;586(19):3324-9. doi: 10.1016/j.febslet.2012.07.009. Epub 2012 Jul 22.
Type II restriction endonucleases (REases) exist in multiple oligomeric forms. The tetrameric REases have two DNA binding interfaces and must synapse two recognition sites to achieve cleavage. It was hypothesised that binding of two recognition sites by tetrameric enzymes contributes to their fidelity. Here, we experimentally determined the fidelity for Bse634I REase in different oligomeric states. Surprisingly, we find that tetramerisation does not increase REase fidelity in comparison to the dimeric variant. Instead, an inherent ability to act concertedly at two sites provides tetrameric REase with a safety-catch to prevent host DNA cleavage if a single unmodified site becomes available.
II 型限制内切酶（REases）以多种多聚体形式存在。四聚体 REases 具有两个 DNA 结合界面，必须连接两个识别位点才能实现切割。人们假设四聚体酶结合两个识别位点有助于提高其保真度。在这里，我们通过实验确定了 Bse634I REase 在不同多聚体状态下的保真度。令人惊讶的是，我们发现与二聚体变体相比，四聚体化并没有提高 REase 的保真度。相反，如果出现单个未修饰的位点，协同作用于两个位点的固有能力为四聚体 REase 提供了安全保障，以防止对宿主 DNA 的切割。
