O'Brien Kevin M, Lindsay Elizabeth L, Starai Vincent J
Department of Microbiology, University of Georgia, Athens, Georgia, Unites States of America.
Department of Microbiology, University of Georgia, Athens, Georgia, Unites States of America; Department of Infectious Diseases, University of Georgia, Athens, Georgia, United States of America.
PLoS One. 2015 Feb 2;10(2):e0116824. doi: 10.1371/journal.pone.0116824. eCollection 2015.
The intracellular pathogen, Legionella pneumophila, relies on numerous secreted effector proteins to manipulate host endomembrane trafficking events during pathogenesis, thereby preventing fusion of the bacteria-laden phagosome with host endolysosomal compartments, and thus escaping degradation. Upon expression in the surrogate eukaryotic model Saccharomyces cerevisiae, we find that the L. pneumophila LegC7/YlfA effector protein disrupts the delivery of both biosynthetic and endocytic cargo to the yeast vacuole. We demonstrate that the effects of LegC7 are specific to the endosome:vacuole delivery pathways; LegC7 expression does not disrupt other known vacuole-directed pathways. Deletions of the ESCRT-0 complex member, VPS27, provide resistance to the LegC7 toxicity, providing a possible target for LegC7 function in vivo. Furthermore, a single amino acid substitution in LegC7 abrogates both its toxicity and ability to alter endosomal traffic in vivo, thereby identifying a critical functional domain. LegC7 likely inhibits endosomal trafficking during L. pneumophila pathogenesis to prevent entry of the phagosome into the endosomal maturation pathway and eventual fusion with the lysosome.
细胞内病原体嗜肺军团菌在致病过程中依靠众多分泌效应蛋白来操控宿主内膜运输事件，从而阻止载有细菌的吞噬体与宿主内溶酶体区室融合，进而逃避降解。在替代真核模型酿酒酵母中表达后，我们发现嗜肺军团菌的LegC7/YlfA效应蛋白会破坏生物合成和内吞货物向酵母液泡的运输。我们证明LegC7的作用对内涵体：液泡运输途径具有特异性；LegC7的表达不会破坏其他已知的液泡导向途径。ESCRT-0复合物成员VPS27的缺失赋予了对LegC7毒性的抗性，这为LegC7在体内的功能提供了一个可能的靶点。此外，LegC7中的单个氨基酸替换消除了其毒性以及在体内改变内涵体运输的能力，从而确定了一个关键功能域。LegC7可能在嗜肺军团菌致病过程中抑制内涵体运输，以防止吞噬体进入内涵体成熟途径并最终与溶酶体融合。
