Hiraga S, Ichinose C, Niki H, Yamazoe M
Department of Molecular Cell Biology, Kumamoto University School of Medicine, Japan.
Mol Cell. 1998 Feb;1(3):381-7. doi: 10.1016/s1097-2765(00)80038-6.
Using immunofluorescence microscopy, we have found that SeqA protein, a regulator of replication initiation, is localized as discrete fluorescent foci in E. coli wild-type cells. Surprisingly, SeqA foci were observed also in an oriC deletion mutant. Statistical analysis revealed that a SeqA focus is localized at midcell in newborn cells. The SeqA focus is duplicated and tethered at midcell until an FtsZ ring is formed. Subsequently, these foci migrate in opposite directions toward cell quarter sites and remain tethered there until the cell divides. The cell cycle-dependent bidirectional migration of SeqA-DNA complexes is quite different from the migration pattern of oriC Dna copies. MukB protein is required for correct localization of SeqA complexes by an unknown mechanism.
利用免疫荧光显微镜技术，我们发现复制起始调控因子SeqA蛋白在大肠杆菌野生型细胞中定位于离散的荧光焦点。令人惊讶的是，在oriC缺失突变体中也观察到了SeqA焦点。统计分析表明，一个SeqA焦点定位于新生细胞的细胞中部。SeqA焦点会复制并拴系在细胞中部，直到形成FtsZ环。随后，这些焦点向相反方向迁移至细胞四分之一位点，并一直拴系在那里直到细胞分裂。SeqA-DNA复合物依赖细胞周期的双向迁移与oriC Dna拷贝的迁移模式截然不同。MukB蛋白通过未知机制参与SeqA复合物的正确定位。
