Phage T4-like intermediates of DNA replication and recombination in the mitochondria of the higher plant Chenopodium album (L.)
Phage T4-like intermediates of DNA replication and recombination in the mitochondria of the higher plant Chenopodium album (L.)
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DOI：
10.1007/s002940050532
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发表时间：
2000-05-01
期刊：
影响因子：
2.5
通讯作者：
Börner, T
中科院分区：
文献类型：
--
作者：
Backert, S;Börner, T
本文研究了从藜（Chenopodium album（L.）通过电子显微镜观察整个生长周期。我们确定了几种类型的潜在的重组和复制中间体，包括玫瑰花结样结构，以及其他分支和西格玛样分子。这些结构的绝对量和相对量在生长周期中发生了巨大的变化，表明mt基因组的结构组织具有很高的动态性。莲座状分子的大小为2-5个基因组单位，并发现含有推定的复制叉和重组中间体中已知的“Holliday”连接。在培养的第一天，大量的rophylaxis，和他们的急剧减少，在静止生长阶段，被认为是负相关的线性分子的40-200 kb的数量的变化。这一观察结果表明，线性分子参与了巨大的分支玫瑰花状结构的形成。以前发现大多数线性分子具有至少一个单链末端，这可能允许其他双链分子的重组侵入。因此，重组事件可能导致形成更复杂的分子并启动类似于噬菌体T4的复制。我们提出了一个共存的重组依赖的复制模式与一个可能的重组无关的滚动循环复制模式在线粒体的C。专辑
We have studied intermediates of the recombination and replication of chromosomal mitochondrial (mt) DNA prepared from suspension cultured cells of Chenopodium album (L.) by electron microscopy during the whole growth cycle. We identified several types of potential recombination and replication intermediates including rosette-like structures, as well as other branched and sigma-like molecules. The absolute and relative amounts of these structures changed dramatically during the growth cycle, indicating high dynamics in the structural organization of the mt genome. The rosette-like molecules had sizes of 2-5 genome units and were found to contain putative replication forks and 'Holliday'-junctions known from recombination intermediates. The high number of rosettes during the first days of culture, and their drastic reduction in the stationary growth stage, were found to be inversely related to changes in the quantity of linear molecules of 40-200 kb. This observation suggests that linear molecules participate in the formation of giant branched rosette-like structures. Most linear molecules were previously found to have at least one single-stranded end, which may allow recombinative invasion of other double-stranded molecules. Thus, recombination events may lead to the formation of more complex molecules and initiate replication similar to phage T4. We propose the coexistence of a recombination-dependent mode of replication with a presumably recombination-independent rolling-circle mode of replication in the mitochondria of C. album.