Department of Microbiology and Immunology, College of Medicine, University of Louisville, Louisville, KY, USA.
Virulence. 2013 May 15;4(4):307-14. doi: 10.4161/viru.24290. Epub 2013 Mar 27.
Legionella pneumophila is an aquatic organism that interacts with amoebae and ciliated protozoa as the natural hosts, and this interaction plays a central role in bacterial ecology and infectivity. Upon transmission to humans, L. pneumophila infect and replicate within alveolar macrophages causing pneumonia. Intracellular proliferation of L. pneumophila within the two evolutionarily distant hosts is facilitated by bacterial exploitation of evolutionarily conserved host processes that are targeted by bacterial protein effectors injected into the host cell by the Dot/Icm type VIB translocation system. Although cysteine is semi-essential for humans and essential for amoeba, it is a metabolically favorable source of carbon and energy generation by L. pneumophila. To counteract host limitation of cysteine, L. pneumophila utilizes the AnkB Dot/Icm-translocated F-box effector to promote host proteasomal degradation of polyubiquitinated proteins within amoebae and human cells. Evidence indicates ankB and other Dot/Icm-translocated effector genes have been acquired through inter-kingdom horizontal gene transfer.
嗜肺军团菌是一种水生生物，与变形虫和纤毛原生动物等自然宿主相互作用，这种相互作用在细菌生态学和感染性中起着核心作用。在传播给人类后，嗜肺军团菌感染并在肺泡巨噬细胞内复制，导致肺炎。嗜肺军团菌在这两个进化上相距甚远的宿主中的细胞内增殖是通过细菌利用进化上保守的宿主过程来促进的，这些过程被细菌蛋白效应子靶向，这些效应子通过 Dot/Icm 型 VIB 转位系统注入宿主细胞。尽管半胱氨酸对半胱氨酸对人类来说是半必需的，对变形虫来说是必需的，但它是嗜肺军团菌生成碳和能量的代谢上有利的来源。为了抵消宿主对半胱氨酸的限制，嗜肺军团菌利用 AnkB Dot/Icm 转位 F 盒效应子促进宿主蛋白酶体降解变形虫和人细胞中的多泛素化蛋白。有证据表明 ankB 和其他 Dot/Icm 转位效应子基因是通过种间水平基因转移获得的。
