Correct chromosomal segregation, coordinated with cell division, is crucial for bacterial survival, but despite extensive studies, the mechanisms underlying this remain incompletely understood in mycobacteria. We report a detailed investigation of the dynamic interactions between ParA and ParB partitioning proteins in Mycobacterium smegmatis using microfluidics and time-lapse fluorescence microscopy to observe both proteins simultaneously. During growth and division, ParB presents as a focused fluorescent spot that subsequently splits in two. One focus moves towards a higher concentration of ParA at the new pole, while the other moves towards the old pole. We show ParB movement is in part an active process that does not rely on passive movement associated with cell growth. In some cells, another round of ParB segregation starts before cell division is complete, consistent with initiation of a second round of chromosome replication. ParA fluorescence distribution correlates with cell size, and in sister cells, the larger cell inherits a local peak of concentrated ParA, while the smaller sister inherits more homogeneously distributed protein. Cells which inherit more ParA grow faster than their sister cell, raising the question of whether inheritance of a local concentration of ParA provides a growth advantage. Alterations in levels of ParA and ParB were also found to disturb cell growth.

正确的染色体分离以及细胞分裂对于细菌的存活至关重要，但是尽管进行了广泛的研究，但在分枝杆菌中仍未完全理解其机制。我们报告了耻垢分枝杆菌中ParA和ParB分区蛋白之间的动态相互作用的详细调查。使用微流控和延时荧光显微镜同时观察两种蛋白质。在生长和分裂过程中，ParB表现为聚焦荧光点，随后又分成两部分。一个重点转移到新极上更高的ParA浓度，而另一个重点转移到旧极上。我们显示ParB运动部分是主动过程，不依赖于与细胞生长相关的被动运动。在某些细胞中，另一轮ParB分离在细胞分裂完成之前开始，这与第二轮染色体复制的启动一致。ParA荧光分布与细胞大小相关，在姐妹细胞中，较大的细胞继承了浓缩的ParA的局部峰，而较小的姐妹则继承了分布更均匀的蛋白质。继承更多ParA的细胞比其姊妹细胞生长更快，这引发了一个问题，即局部浓缩ParA的遗传是否提供了生长优势。还发现ParA和ParB水平的改变会干扰细胞生长。