Wu Ling Juan, Errington Jeff
Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK.
EMBO J. 2002 Aug 1;21(15):4001-11. doi: 10.1093/emboj/cdf393.
The cis-acting sequences required for chromosome segregation are poorly understood in most organisms, including bacteria. Sporulating cells of Bacillus subtilis undergo an unusual asymmetric cell division during which the origin of DNA replication (oriC) region of the chromosome migrates to an extreme polar position. We have now characterized the sequences required for this migration. We show that the previously characterized soj-spo0J chromosome segregation system is not essential for chromosome movement to the cell pole, so this must be driven by an additional segregation mechanism. Observations on a large set of precisely engineered chromosomal inversions and translocations have identified a polar localization region (PLR), which lies approximately 150-300 kbp to the left of oriC. Surprisingly, oriC itself has no involvement in this chromosome segregation system. Dissection of the PLR showed that it has internal functional redundancy, reminiscent of the large diffuse centromeres of most eukaryotic cells.
在包括细菌在内的大多数生物体中，对于染色体分离所需的顺式作用序列了解甚少。枯草芽孢杆菌的芽孢形成细胞会经历一种不同寻常的不对称细胞分裂，在此过程中，染色体的DNA复制起点（oriC）区域会迁移到一个极端的极性位置。我们现在已经对这种迁移所需的序列进行了表征。我们表明，先前表征的soj-spo0J染色体分离系统对于染色体向细胞极的移动并非必不可少，因此这一过程必定由一种额外的分离机制驱动。对大量精确构建的染色体倒位和易位的观察确定了一个极性定位区域（PLR），它位于oriC左侧约150 - 300 kbp处。令人惊讶的是，oriC本身并不参与这个染色体分离系统。对PLR的剖析表明它具有内部功能冗余，这让人联想到大多数真核细胞中大型的弥散着丝粒。
