GIN-MEDIATED RECOMBINATION OF CATENATED AND KNOTTED DNA SUBSTRATES - IMPLICATIONS FOR THE MECHANISM OF INTERACTION BETWEEN CIS-ACTING SITES
GIN-MEDIATED RECOMBINATION OF CATENATED AND KNOTTED DNA SUBSTRATES - IMPLICATIONS FOR THE MECHANISM OF INTERACTION BETWEEN CIS-ACTING SITES
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DOI：
10.1016/0092-8674(89)90411-x
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发表时间：
1989-07-14
期刊：
影响因子：
64.5
通讯作者：
COZZARELLI, NR
中科院分区：
文献类型：
--
作者：
KANAAR, R;VANDEPUTTE, P;COZZARELLI, NR
噬菌体Mu的Gin DNA倒位系统通常需要在同一超螺旋DNA分子上含有两个反向重组位点（gix）和增强子序列的底物。反应机理进行了研究，通过分离这些网站上的链状环。在一个环上具有gix位点并且在另一个环上具有增强子的链烯有效地重组。因此，增强子是完全功能性的，即使它位于反式的gix网站。环之间的多个连接是重组所必需的。多重连接的索烃与gix网站上的单独的圆圈，其中之一含有增强子，也是有效的基板。重组携带直接重复的gix位点的打结构建体。链状和打结的基质也必须是超螺旋的。这些实验排除了简单的跟踪或成环模型，以解释为什么增强子和gix位点必须与标准底物顺式。相反，Gin突触复合体需要这三个位点以右手方式相互交织，其中Gix位点具有独特的极性。这种几何结构是通过DNA底物的分支来实现的，并且需要超螺旋、连锁或打结的能量和结构。
The Gin DNA-inversion system of bacteriophage Mu normally requires a substrate containing two inverted recombination sites (gix) and an enhancer sequence on the same supercoiled DNA molecule. The reaction mechanism was investigated by separating these sites on catenated rings. Catenanes with the gix sites on one circle and the enhancer on the other recombined efficiently. Thus, the enhancer was fully functional even though it was located in trans to the gix sites. Multiple links between the rings are required for recombination. Multiply linked catenanes with gix sites on separate circles, one of which contained the enhancer, were also efficient substrates. Knotted constructs carrying directly repeated gix sites were recombined. Catenated and knotted substrates must also be supercoiled. These experiments eliminate simple tracking or looping models as explanations for why the enhancer and gix sites must be in cis with standard substrates. Rather, the Gin synaptic complex requires the three sites to be mutually intertwined in a right-handed fashion with a unique polarity of the gix sites. This geometry is achieved by branching of the DNA substrate and requires the energy and structure of supercoiling, catenation, or knotting.