Department of Microbiology and Immunology, Room MS-410, College of Medicine, University of Louisville, Louisville, Kentucky 40292, USA.
Infect Immun. 2010 Mar;78(3):1123-34. doi: 10.1128/IAI.00913-09. Epub 2009 Dec 22.
Although most Dot/Icm-translocated effectors of Legionella pneumophila are not required for intracellular proliferation, the eukaryotic-like ankyrin effectors, AnkH and AnkJ are required for intracellular proliferation. In this report, we show that the IcmSW chaperones are essential for translocation of AnkJ but not AnkH. The 10 C-terminal residues and the ANK domains of AnkH and AnkJ are required for translocation. Our data indicate that the two ANK domains of AnkH are critical domains required for the function of the effector in intracellular replication of L. pneumophila. The ankH and ankJ mutants are severely defective in intrapulmonary proliferation in mice. Expression of AnkH and AnkJ fusions within HEK293 cells show a punctuate distribution in the cytosol but no association with endocytic vesicles, the Golgi apparatus or the endoplasmic reticulum. Interestingly, the defect in intracellular proliferation of the ankH or ankJ mutants is rescued in HEK293 cells expressing the respective protein. We conclude that AnkH and AnkJ are effectors translocated by the Dot/Icm system by distinct mechanisms and modulate distinct cytosolic processes in the host cell.
虽然大多数军团菌属肺炎的 Dot/Icm 易位效应物对于细胞内增殖并非必需，但类真核的锚蛋白效应物 AnkH 和 AnkJ 对于细胞内增殖是必需的。在本报告中，我们表明，IcmSW 伴侣蛋白对于 AnkJ 的易位是必需的，但对于 AnkH 则不是。AnkH 和 AnkJ 的 10 个 C 末端残基和 ANK 结构域对于易位是必需的。我们的数据表明，AnkH 的两个 ANK 结构域是效应物在肺炎军团菌细胞内复制中发挥功能所必需的关键结构域。ankH 和 ankJ 突变体在小鼠肺内增殖中严重缺陷。在 HEK293 细胞中表达 AnkH 和 AnkJ 融合蛋白显示在细胞质中呈点状分布，但与内吞小泡、高尔基体或内质网没有关联。有趣的是，在表达相应蛋白的 HEK293 细胞中，ankH 或 ankJ 突变体的细胞内增殖缺陷得到挽救。我们的结论是，AnkH 和 AnkJ 是由 Dot/Icm 系统通过不同机制易位的效应物，并且在宿主细胞中调节不同的细胞质过程。
