Changes in network topology during the replication of kinetoplast DNA
Changes in network topology during the replication of kinetoplast DNA
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DOI：
10.1002/j.1460-2075.1995.tb00325.x
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发表时间：
1995-12-15
期刊：
影响因子：
11.4
通讯作者：
Cozzarelli, NR
中科院分区：
文献类型：
--
作者：
Chen, JH;Englund, PT;Cozzarelli, NR
束状凤仙花的着丝质体DNA是一个包含数千个拓扑上互锁的DNA小环的网络。在预复制的形式I网络中，5000个小圆中的每一个都是完整的，并且平均连接到三个相邻的小圆（即小圆价为3）。复制涉及从网络内部释放小圆，合成有缺口或缺口的子代小圆，并将子代连接到网络外围，最终结果是由10,000个有缺口或缺口的形式II网络。在S阶段，外围新复制的小圆的密度是I型网络中小圆的两倍，这表明价可能高达6。由于去除完整的小圆而产生的中心区域的大多数孔被修复，因此中心密度和价保持不变。就像在预复制网络中一样。当迷你环复制在S阶段结束时完成时，孤立网络的表面积与预复制网络相同，尽管其迷你环的数量是预复制网络的两倍。在G(2)阶段，形式II网络经历重塑，面积加倍，价价减少到3，最后，小环中的中断被修复，两倍大小的网络分裂成两个。
Kinetoplast DNA of Crithidia fasciculata is a network containing several thousand topologically interlocked DNA minicircles. In the prereplicative Form I network, each of the 5000 minicircles is intact and linked to an average of three neighbors (i.e. the minicircle valence is 3), Replication involves the release of minicircles from the interior of the network, the synthesis of nicked or gapped progeny minicircles and the attachment of the progeny to the network periphery, The ultimate result is a Form II network of 10 000 nicked or gapped minicircles. Our measurements of minicircle valence and density, and the network's surface area, revealed striking changes in network topology during replication, During the S phase, the peripheral newly replicated minicircles have a density twice that of minicircles in Form I networks, which suggests that the valence might be as high as 6, Most of the holes in the central region that occur from the removal of intact minicircles are repaired so that the central density and valence remain the same, as in prereplicative networks. When minicircle replication is complete at the end of the S phase, the isolated network has the surface area of a prereplicative network, despite having twice the number of minicircles. During the G(2) phase, the Form II network undergoes a remodeling in which the area doubles and the valence is reduced to 3, Finally, the interruptions in the minicircles are repaired and the double-sized network splits in two.