Department of Microbiology, College of Physicians and Surgeons, Columbia University, New York 10032, USA.
Cold Spring Harb Perspect Biol. 2009 Dec;1(6):a003368. doi: 10.1101/cshperspect.a003368. Epub 2009 Sep 9.
Simple visual inspection of bacteria indicated that, at least in some otherwise symmetric cells, structures such as flagella were often seen at a single pole. Because these structures are composed of proteins, it was not clear how to reconcile these observations of morphological asymmetry with the widely held view of bacteria as unstructured "bags of enzymes." However, over the last decade, numerous GFP tagged proteins have been found at specific intracellular locations such as the poles of the cells, indicating that bacteria have a high degree of intracellular organization. Here we will explore the role of chromosomal asymmetry and the presence of "new" and "old" poles that result from the cytokinesis of rod-shaped cells in establishing bipolar and monopolar protein localization patterns. This article is intended to be illustrative, not exhaustive, so we have focused on examples drawn largely from Caulobacter crescentus and Bacillus subtilis, two bacteria that undergo dramatic morphological transformation. We will highlight how breaking monopolar symmetry is essential for the correct development of these organisms.
简单的细菌外观观察表明，至少在一些其他方面对称的细胞中，鞭毛等结构经常出现在一个极上。由于这些结构是由蛋白质组成的，因此很难将这些形态不对称的观察结果与普遍认为的细菌是无结构的“酶袋”观点相协调。然而，在过去的十年中，已经在细胞的两极等特定的细胞内位置发现了许多 GFP 标记的蛋白质，这表明细菌具有高度的细胞内组织。在这里，我们将探讨染色体不对称性的作用，以及由杆状细胞的细胞分裂产生的“新”极和“老”极的存在，如何在建立双极和单极蛋白定位模式中发挥作用。本文旨在说明问题，而不是详尽无遗，因此我们主要集中在来自新月柄杆菌和枯草芽孢杆菌的例子上，这两种细菌经历了剧烈的形态转变。我们将重点介绍打破单极对称性对这些生物体正确发育的重要性。
