Bennett R J, West S C
Imperial Cancer Research Fund, Clare Hall Laboratories, South Mimms, Herts, United Kingdom.
Proc Natl Acad Sci U S A. 1996 Oct 29;93(22):12217-22. doi: 10.1073/pnas.93.22.12217.
The RuvC protein of Escherichia coli catalyzes the resolution of recombination intermediates during genetic recombination and the recombinational repair of damaged DNA. Resolution involves specific recognition of the Holliday structure to form a complex that exhibits twofold symmetry with the DNA in an open configuration. Cleavage occurs when strands of like polarity are nicked at the sequence 5'-WTT decreases S-3' (where W is A or T and S is G or C). To determine whether the cleavage site needs to be located at, or close to, the point at which DNA strands exchange partners, Holliday structures were constructed with the junction points at defined sites within this sequence. We found that the efficiency of resolution was optimal when the cleavage site was coincident with the position of DNA strand exchange. In these studies, junction targeting was achieved by incorporating uncharged methyl phosphonates into the DNA backbone, providing further evidence for the importance of charge-charge repulsions in determining DNA structure.
大肠杆菌的RuvC蛋白在基因重组过程中催化重组中间体的拆分以及受损DNA的重组修复。拆分涉及对霍利迪结构的特异性识别，以形成一种与处于开放构型的DNA具有二重对称性的复合物。当相同极性的链在序列5'-WTT降低S-3'（其中W为A或T，S为G或C）处被切口时，就会发生切割。为了确定切割位点是否需要位于DNA链交换伙伴的点处或其附近，构建了霍利迪结构，其连接点位于该序列内的特定位置。我们发现，当切割位点与DNA链交换的位置重合时，拆分效率最佳。在这些研究中，通过将不带电荷的甲基膦酸酯掺入DNA主链来实现连接点靶向，这为电荷-电荷排斥在确定DNA结构中的重要性提供了进一步的证据。
