Ehrbar Kristin, Hardt Wolf-Dietrich
Institute of Microbiology, ETH Zurich, Schmelzbergstrasse 7, 8092 Zurich, Switzerland.
Infect Genet Evol. 2005 Jan;5(1):1-9. doi: 10.1016/j.meegid.2004.07.004.
Salmonella spp. are Gram-negative bacteria which cause infections ranging from mild, self-limiting enterocolitis to systemic (typhoid) disease. Recent work has established that the genetic makeup varies considerably between different Salmonella strains. Phages play an important role in this diversity. In fact, Salmonella has emerged as a prime example for the involvement of virulence factor encoding phages in the emergence of new epidemic strains. Among other virulence factors, Salmonella enterica utilizes two specialized protein secretion systems termed type III secretion systems (TTSS) to deliver effector proteins into host cells which manipulate host cell signaling cascades. These two TTSS and several effectors are encoded within Salmonella pathogenicity islands 1 and 2. Some effectors including SopE, SspH1, SseI and SopE2 are encoded by phages or phage remnants. These phage-encoded effectors seem to be transferred between different Salmonella strains. They have attracted much interest because they might contribute to the evolution of Salmonella spp. Here we will focus on SopEPhi which encodes the SPI-1 effector SopE. It provides an excellent example to illustrate how horizontally transferred effector proteins are integrated into the complex regulatory network of a TTSS in a recipient bacterium. Additional data supporting the hypothesis are presented. This is a prerequisite to allow optimization of the bacterium host cell interaction by reassortment of the phage-encoded effector protein repertoire.
沙门氏菌属是革兰氏阴性菌，可引发从轻度、自限性小肠结肠炎到全身性（伤寒）疾病等多种感染。最近的研究表明，不同沙门氏菌菌株之间的基因组成差异很大。噬菌体在这种多样性中起着重要作用。事实上，沙门氏菌已成为毒力因子编码噬菌体参与新流行菌株出现的一个典型例子。除其他毒力因子外，肠炎沙门氏菌利用两种特殊的蛋白质分泌系统，即III型分泌系统（TTSS），将效应蛋白传递到宿主细胞中，从而操纵宿主细胞信号级联反应。这两种TTSS和几种效应蛋白由沙门氏菌致病岛1和2编码。一些效应蛋白，包括SopE、SspH1、SseI和SopE2，由噬菌体或噬菌体残余物编码。这些噬菌体编码的效应蛋白似乎在不同的沙门氏菌菌株之间转移。它们引起了广泛关注，因为它们可能有助于沙门氏菌属的进化。在这里，我们将重点关注编码SPI-1效应蛋白SopE的SopEPhi。它提供了一个很好的例子来说明水平转移的效应蛋白是如何整合到受体细菌中TTSS的复杂调控网络中的。还展示了支持该假设的其他数据。这是通过重新组合噬菌体编码的效应蛋白库来优化细菌与宿主细胞相互作用的先决条件。
