Hajduk S L, Klein V A, Englund P T
Cell. 1984 Feb;36(2):483-92. doi: 10.1016/0092-8674(84)90241-1.
The kinetoplast DNA of Crithidia fasciculata is a massive network composed of thousands of topologically interlocked circles. Most of these circles are minicircles (2.5 kb), and about 50 are maxicircles (37 kb). Previous studies showed that minicircles replicate, after release from the network, via Cairns (theta) intermediates. Here we show that maxicircles replicate, while attached to the network, by an entirely different mechanism involving rolling circle intermediates. After the network-bound maxicircle has finished replication, the branch of the rolling circle is apparently cleaved off to form a linear free maxicircle. A restriction map of the linearized free maxicircles shows that these molecules have unique termini, one of which presumably corresponds to the replication origin.
纤细短膜虫的动质体DNA是一个由数千个拓扑学上相互连锁的环组成的巨大网络。这些环大多数是微环（2.5 kb），约50个是大环（37 kb）。先前的研究表明，微环从网络释放后通过凯恩斯（θ）中间体进行复制。在此我们表明，大环在附着于网络时通过一种完全不同的涉及滚环中间体的机制进行复制。在与网络相连的大环完成复制后，滚环的分支显然被切断以形成线性游离大环。线性化游离大环的限制酶切图谱表明，这些分子具有独特的末端，其中一个大概对应于复制起点。
