Department of Bioorganic Chemistry, Max Planck Institute for Chemical Ecology, Hans-Knoell-Strasse 8, 07745 Jena, Germany.
J Mol Biol. 2010 Apr 9;397(4):906-16. doi: 10.1016/j.jmb.2010.02.008. Epub 2010 Feb 13.
Rod-shaped bacteria such as Escherichia coli divide by binary fission. They inherit an old pole from the parent cell. The new pole is recently derived from the septum. Because the chemoreceptor accumulates linearly with time on the cell pole, the old pole carries more receptors than does the new pole. Here, further evidence is provided that the old pole appears more frequently at the rear when bacteria swim. This phenomenon had been observed, yet not extensively explored in the literature. The biased swimming orientation is the consequence of the asymmetric distribution of flagella over the cell surface. On about 75% of cells, there are more flagella on the old-pole half of the cell than on the new-pole half, regardless of growth conditions. Most flagella are lateral, and few were found on the cell pole per se. The asymmetric flagellar distribution makes cells more efficient in chemotaxis. Both swimming orientation and receptor localization are components of chemotaxis, by which bacteria follow environmental stimuli. If unipolarly flagellated cells, such as the swarmer cells of Caulobacter crescentus, are regarded as 100% polar with respect to chemotaxis, E. coli is about 75%. The difference is quantitative. The peritrichous flagellation might enhance the motility and chemotaxis in the viscous environment of enteric bacteria.
杆状细菌，如大肠杆菌，通过二分分裂进行分裂。它们从母细胞继承一个旧的极。新的极是最近从隔膜衍生而来的。由于化学感受器在线性地在细胞极上积累，旧极携带的受体比新极多。在这里，进一步的证据表明，当细菌游动时，旧极更频繁地出现在后部。这种现象已经被观察到，但在文献中并没有被广泛探讨。这种偏向的游动方向是由于鞭毛在细胞表面上的不对称分布所致。在大约 75%的细胞中，旧极半的细胞上的鞭毛比新极半的细胞多，无论生长条件如何。大多数鞭毛是侧向的，在细胞极上很少发现。不对称的鞭毛分布使细胞在趋化性方面更有效率。游动方向和受体定位都是细菌跟随环境刺激的趋化性的组成部分。如果将单极鞭毛的细胞，如新月形柄杆菌的游动细胞，视为在趋化性方面 100%极性的话，那么大肠杆菌约为 75%。差异是定量的。周生鞭毛可能会增强肠道细菌粘性环境中的运动性和趋化性。
