Single-molecule analysis reveals the molecular bearing mechanism of DNA strand exchange by a serine recombinase
Single-molecule analysis reveals the molecular bearing mechanism of DNA strand exchange by a serine recombinase
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DOI：
10.1073/pnas.10184361
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发表时间：
2011-05-03
影响因子：
11.1
通讯作者：
Marko, John F.
中科院分区：
文献类型：
--
作者：
Bai, Hua;Sun, Mingxuan;Marko, John F.
DNA重组酶通过突触两半的刚体相对旋转交换双链DNA，由平坦的蛋白质-蛋白质相互作用表面介导。我们目前的证据，这种旋转运动的一个简单的丝氨酸重组酶，BXB 1噬菌体整合酶，从单DNA为基础的超螺旋释放试验，使我们能够遵循交叉位点切割，旋转，再连接，并在真实的时间产品释放。我们还利用双DNA编织松弛实验观察了突触旋转对两个长分子反应的影响。松弛和解编织快速（平均分别为54和70转/秒）和完全，没有明显的停顿。然而，在类似的测定中，与旋转相关的分子摩擦大于I型拓扑异构酶。令人惊讶的是，我们发现突触可以保持旋转“开放”许多分钟。
DNA recombinases exchange duplex DNAs by rigid-body relative rotation of the two halves of the synapse, mediated by a flat protein-protein interaction surface. We present evidence for this rotational motion for a simple serine recombinase, the Bxb1 phage integrase, from a single-DNA-based supercoil-release assay that allows us to follow crossover site cleavage, rotation, religation, and product release in real time. We have also used a two-DNA braiding-relaxation experiment to observe the effect of synapse rotation in reactions on two long molecules. Relaxation and un-braiding are rapid (averaging 54 and 70 turns/s, respectively) and complete, with no discernible pauses. Nevertheless, the molecular friction associated with rotation is larger than that of type-I topoisomerases in a similar assay. Surprisingly we find that the synapse can stay rotationally "open" for many minutes.