Backert S
Institut für Biologie, Humboldt-Universität zu Berlin, Chausseestrasse 117, Berlin, D-10115, Germany.
Plasmid. 2000 Mar;43(2):166-70. doi: 10.1006/plas.1999.1437.
The structure of sigma-like mitochondrial DNA molecules prepared from suspension cultured cells of Chenopodium album (L.) was studied by electron microscopy. These molecules were highly variable in size, ranging from about 1 to 104 kb, and had single- and double-stranded regions typical for rolling circle replicating intermediates. Partial denaturation studies confirmed that these structures constitute rolling circles. Close inspection of the circle-tail junctions of the replication fork at high magnification suggests that in circles with a double-stranded tail, both strands of the tail seem to be covalently attached to the circle in about 27% of the molecules. This observation can be explained by a phenomenon called strand switching or strand splippage during rolling circle replication, similar to a mechanism proposed for bacterial replicons or in vitro replicating constructs harboring bacteriophage T4 replication origins.
通过电子显微镜研究了从藜（Chenopodium album (L.)）悬浮培养细胞中制备的类sigma线粒体DNA分子的结构。这些分子大小高度可变，范围约为1至104 kb，具有滚环复制中间体典型的单链和双链区域。部分变性研究证实这些结构构成滚环。在高倍放大下仔细检查复制叉的环尾连接处表明，在具有双链尾的环中，约27%的分子中尾的两条链似乎都共价连接到环上。这一观察结果可以用滚环复制过程中称为链切换或链滑移的现象来解释，类似于为细菌复制子或携带噬菌体T4复制起点的体外复制构建体提出的机制。
