Itaya M, Tanaka T
Mitsubishi Kasei Institute of Life Sciences, Tokyo, Japan.
FEBS Lett. 1999 Apr 9;448(2-3):235-8. doi: 10.1016/s0014-5793(99)00351-8.
The plastic Bacillus subtilis genome was dissected into two physically separate genomes, the 3.9 Mb main genome and the 0.3 Mb subgenome. DNA replication of the main genome was initiated from the normal replication origin (oriC) and that of the subgenome was from a 7.2 kb oriN-containing fragment artificially inserted. When the 7.2 kb fragment was shortened to a 1.5 kb fragment that contains oriN but lacks the segregational function, the subgenome became unstable and was rapidly lost from the cell, producing inviable cells due to the loss of essential genes carried by the subgenome. Stable survivors were isolated in which the subgenome had re-integrated and multiplied in the main genome. These results suggest that a reduced genetic stability of the subgenome induces size variation of the B. subtilis genome.
将枯草芽孢杆菌的人工基因组解析为两个物理上分离的基因组，即3.9 Mb的主基因组和0.3 Mb的次基因组。主基因组的DNA复制从正常复制起点（oriC）起始，而次基因组的DNA复制则从人工插入的一个含7.2 kb oriN的片段起始。当7.2 kb的片段缩短为一个1.5 kb的片段，该片段含有oriN但缺乏分离功能时，次基因组变得不稳定并迅速从细胞中丢失，由于次基因组携带的必需基因丢失而产生无活力的细胞。分离出了稳定的存活菌株，其中次基因组已重新整合并在主基因组中增殖。这些结果表明，次基因组遗传稳定性的降低会导致枯草芽孢杆菌基因组大小的变化。
