Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA.
Mol Microbiol. 2010 Apr;76(1):173-89. doi: 10.1111/j.1365-2958.2010.07088.x. Epub 2010 Feb 10.
The bacterium Caulobacter crescentus has morphologically and functionally distinct cell poles that undergo sequential changes during the cell cycle. We show that the PopZ oligomeric network forms polar ribosome exclusion zones that change function during cell cycle progression. The parS/ParB chromosomal centromere is tethered to PopZ at one pole prior to the initiation of DNA replication. During polar maturation, the PopZ-centromere tether is broken, and the PopZ zone at that pole then switches function to act as a recruitment factor for the ordered addition of multiple proteins that promote the transformation of the flagellated pole into a stalked pole. Stalked pole assembly, in turn, triggers the initiation of chromosome replication, which signals the formation of a new PopZ zone at the opposite cell pole, where it functions to anchor the newly duplicated centromere that has traversed the long axis of the cell. We propose that pole-specific control of PopZ function co-ordinates polar development and cell cycle progression by enabling independent assembly and tethering activities at the two cell poles.
新月柄杆菌（Caulobacter crescentus）具有形态和功能上明显不同的细胞极，在细胞周期中经历连续的变化。我们发现，PopZ 寡聚网络形成极性核糖体排除区，在细胞周期进展过程中改变功能。parS/ParB 染色体着丝粒在 DNA 复制开始之前就被系泊在 PopZ 的一个极上。在极性成熟过程中，PopZ-着丝粒的系泊被打破，该极的 PopZ 区随后切换功能，成为多个促进鞭毛极转化为杆状极的有序添加的蛋白质的募集因子。反过来，杆状极的组装触发染色体复制的起始，这标志着在相反的细胞极形成一个新的 PopZ 区，在那里它的功能是固定穿过细胞长轴的新复制的着丝粒。我们提出，PopZ 功能的极特异性控制通过在两个细胞极上实现独立的组装和系泊活动来协调极性发育和细胞周期进展。
