The Min system and nucleoid occlusion are not required for identifying the division site in Bacillus subtilis but ensure its efficient utilization.
The Min system and nucleoid occlusion are not required for identifying the division site in Bacillus subtilis but ensure its efficient utilization.
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DOI：
10.1371/journal.pgen.1002561
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发表时间：
2012
期刊：
影响因子：
4.5
通讯作者：
Harry EJ
中科院分区：
文献类型：
--
作者：
Rodrigues CD;Harry EJ
细胞分裂的精确时间和空间控制对于后代的生存至关重要。目前的普遍观点是，杆状细菌中分裂位点的精确定位是Min系统和类核(染色体)闭塞共同作用的结果。这两个系统都阻止细胞动力学Z环在细胞内不适当的位置组装，将Z环限制在中间细胞的正确位置。在这里，我们证明了在细菌中，枯草杆菌Z环在完全缺乏这两个系统的情况下精确地定位在中细胞上，揭示了这种有机体中识别中细胞的独立于Min和类核封闭的机制的存在。我们进一步证明，在没有Min和Noc蛋白的情况下，Z环在中部细胞的组装被推迟，同时FtsZ在其他潜在的分裂位点积累。这表明，Min和Noc的主要作用是通过防止Z环在潜在的分裂部位(包括细胞极点)组装，确保中细胞分裂部位的有效利用。我们的数据导致我们提出了一个模型，在该模型中，枯草杆菌分裂的空间调控涉及识别中间细胞的分裂位置，这需要Min和类核封闭，以确保在细胞周期的正确时间在那里且仅在那里有效地组装Z环。生物体如何调节生物过程，使其发生在细胞内的正确位置，这是研究中的一个基本问题。细胞分裂的空间调节对于确保DNA平等地分配到新生细胞至关重要。杆状细菌中分裂位点在细胞中心的正确定位通常被认为是通过两个因素的共同作用发生的：(I)类核(染色体)闭塞和(Ii)一组统称为Min系统的蛋白质。细菌细胞分裂的最早阶段是在分裂部位组装一个环，称为Z环。类核闭塞和Min通过阻止Z环在细胞中心以外的所有位置组装而起作用。在这里，我们有一个令人惊讶的发现，在没有这两个因素的情况下，Z环在除法位置上的位置是正确的，但这个过程存在延迟，效率较低。我们提出了一种单独的机制来识别杆状细菌中细胞的分裂位置，类核闭塞和Min确保Z环在那里并且只在那里形成，在正确的时间和每一次。
Precise temporal and spatial control of cell division is essential for progeny survival. The current general view is that precise positioning of the division site at midcell in rod-shaped bacteria is a result of the combined action of the Min system and nucleoid (chromosome) occlusion. Both systems prevent assembly of the cytokinetic Z ring at inappropriate places in the cell, restricting Z rings to the correct site at midcell. Here we show that in the bacterium Bacillus subtilis Z rings are positioned precisely at midcell in the complete absence of both these systems, revealing the existence of a mechanism independent of Min and nucleoid occlusion that identifies midcell in this organism. We further show that Z ring assembly at midcell is delayed in the absence of Min and Noc proteins, while at the same time FtsZ accumulates at other potential division sites. This suggests that a major role for Min and Noc is to ensure efficient utilization of the midcell division site by preventing Z ring assembly at potential division sites, including the cell poles. Our data lead us to propose a model in which spatial regulation of division in B. subtilis involves identification of the division site at midcell that requires Min and nucleoid occlusion to ensure efficient Z ring assembly there and only there, at the right time in the cell cycle. How organisms regulate biological processes so that they occur at the correct place within the cell is a fundamental question in research. Spatial regulation of cell division is vital to ensure equal partitioning of DNA into newborn cells. Correct positioning of the division site at the cell centre in rod-shaped bacteria is generally believed to occur via the combined action of two factors: (i) nucleoid (chromosome) occlusion and (ii) a set of proteins known collectively as the Min system. The earliest stage in bacterial cell division is the assembly of a ring, called the Z ring, at the division site. Nucleoid occlusion and Min work by preventing Z ring assembly at all sites along the cell other than the cell centre. Here we make the surprising discovery that, in the absence of both these factors, Z rings are positioned correctly at the division site, but there is a delay in this process and it is less efficient. We propose that a separate mechanism identifies the division site at midcell in rod-shaped bacteria, and nucleoid occlusion and Min ensure that the Z ring forms there and only there, at the right time and every time.
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