The Legionella pneumophila effector VipA is an actin nucleator that alters host cell organelle trafficking.
The Legionella pneumophila effector VipA is an actin nucleator that alters host cell organelle trafficking.
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DOI：
10.1371/journal.ppat.1002546
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发表时间：
2012-02
期刊：
影响因子：
6.7
通讯作者：
Shuman HA
中科院分区：
文献类型：
--
作者：
Franco IS;Shohdy N;Shuman HA
Legionella pneumophila, the causative agent of Legionnaires' disease, invades and replicates within macrophages and protozoan cells inside a vacuole. The type IVB Icm/Dot secretion system is necessary for the translocation of effector proteins that modulate vesicle trafficking pathways in the host cell, thus avoiding phagosome-lysosome fusion. The Legionella VipA effector was previously identified by its ability to interfere with organelle trafficking in the Multivesicular Body (MVB) pathway when ectopically expressed in yeast. In this study, we show that VipA binds actin in vitro and directly polymerizes microfilaments without the requirement of additional proteins, displaying properties distinct from other bacterial actin nucleators. Microscopy studies revealed that fluorescently tagged VipA variants localize to puncta in eukaryotic cells. In yeast these puncta are associated with actin-rich regions and components of the Multivesicular Body pathway such as endosomes and the MVB-associated protein Bro1. During macrophage infection, native translocated VipA associated with actin patches and early endosomes. When ectopically expressed in mammalian cells, VipA-GFP displayed a similar distribution ruling out the requirement of additional effectors for binding to its eukaryotic targets. Interestingly, a mutant form of VipA, VipA-1, that does not interfere with organelle trafficking is also defective in actin binding as well as association with early endosomes and shows a homogeneous cytosolic localization. These results show that the ability of VipA to bind actin is related to its association with a specific subcellular location as well as its role in modulating organelle trafficking pathways. VipA constitutes a novel type of actin nucleator that may contribute to the intracellular lifestyle of Legionella by altering cytoskeleton dynamics to target host cell pathways. Legionella pneumophila is a facultative intracellular bacterium that can cause an often fatal type of pneumonia known as Legionnaires' disease. In nature, L. pneumophila is found in both fresh water and soil where it parasitizes free-living protists. Upon inhalation of contaminated aerosols, L. pneumophila invades and replicates in alveolar macrophages, leading to inflammation and development of the disease. Legionella uses a type IVB secretion system to translocate effector proteins into the host cell that modify its trafficking pathways and prevent fusion of the newly formed phagosome with the lysosome. One of these effectors is VipA, which, when expressed in yeast interferes with the Multivesicular Body (MVB) pathway. We found that VipA protein binds actin and nucleates its polymerization without additional host factors. VipA localizes in puncta in eukaryotic cells, and these colocalize with actin-rich regions and endosomes. We demonstrate that the ability to disrupt the MVB is associated with the capacity to bind actin. Thus VipA may contribute to the intracellular lifestyle of L. pneumophila by targeting the cytoskeleton in order to disrupt normal vacuolar trafficking pathways in host cells.
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DOI：
10.1073/pnas.0603044103
发表时间：
2006-10-17
影响因子：
11.1
作者：
Jewett, Travis J.;Fischer, Elizabeth R.;Hackstadt, Ted
通讯作者：
Hackstadt, Ted
细胞切拉斯蛋白的作用机理：证据与肌动蛋白丝结束。
影响因子：
7.8
作者：
Brown, S S;Spudich, J A
通讯作者：
Spudich, J A
DOI：
10.1084/jem.158.6.2108
发表时间：
1983-12-01
期刊：
The Journal of experimental medicine
影响因子：
--
作者：
Horwitz MA
通讯作者：
Horwitz MA
芽殖酵母酿酒酵母中内体和肌动蛋白斑块的组装、拆卸和肌动蛋白电缆依赖性运动的活细胞成像。
影响因子：
7.8
作者：
Huckaba, TM;Gay, AC;Pantalena, LF;Yang, HC;Pon, LA
通讯作者：
Pon, LA
影响因子：
64.5
作者：
Kaksonen, M;Toret, CP;Drubin, DG
通讯作者：
Drubin, DG