The Coxiella burnetii Dot/Icm system delivers a unique repertoire of type IV effectors into host cells and is required for intracellular replication.
The Coxiella burnetii Dot/Icm system delivers a unique repertoire of type IV effectors into host cells and is required for intracellular replication.
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DOI：
10.1371/journal.ppat.1002056
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发表时间：
2011-05
期刊：
影响因子：
6.7
通讯作者：
Roy CR
中科院分区：
文献类型：
--
作者：
Carey KL;Newton HJ;Lührmann A;Roy CR
贝氏柯克斯体（Coxiellaburnetii）是一种细胞内病原体，在宿主溶酶体网络的酸化空泡中复制。该病原体编码Dot/Icm IV型分泌系统，其将称为效应子的细菌蛋白质递送至宿主胞质溶胶。为了鉴定新的效应蛋白，在遗传筛选中使用功能类似的嗜肺军团菌Dot/Icm系统来鉴定C.贝氏体基因组DNA，当与腺苷酸环化酶报告基因融合时，其能够指导融合蛋白的Dot/Icm依赖性易位进入哺乳动物宿主细胞。该筛选鉴定了Dot/Icm效应物，其是C. burnetii，与L. pneumophila Dot/Icm效应器。与C.来自不同分离株的伯内特菌基因组序列揭示了编码许多这些效应子的基因的大小和分布的多样性。在真核细胞中检测效应子的定位和功能的研究提供了证据，证明这些蛋白质中的几种对特定宿主细胞器具有亲和力，并且可以破坏细胞功能。使用破坏dot/icm基因座的转座子插入突变的鉴定来验证该装置对于效应子的易位是必不可少的。重要的是，这个C。Burnetii Dot/Icm缺陷突变体被发现是细胞内复制缺陷的。因此，这些数据表明C.贝氏杆菌编码通过Dot/Icm装置转移到宿主细胞中的细菌效应蛋白的独特子集，并且这些效应蛋白发挥的累积活性使C. Burnetii成功地在哺乳动物细胞内建立了支持细胞内复制的生态位。 贝氏柯克斯体（Coxiella burnetii）是一种革兰氏阴性胞内细菌，可引起人类Q热。C.称为Dot/Icm的伯氏菌在功能上类似于嗜肺军团菌的Dot/Icm系统。这里我们使用L。pneumophila筛选C.用于编码效应蛋白的基因的Burnetii文库。我们确定了18个效应子是C。Burnettii的研究表明，当它们在真核细胞中表达时，它们定位于特定的区室，并且可以介导宿主细胞生理学的变化。比较基因组分析揭示了这些新的效应蛋白之间的可塑性，可能与这些临床分离的C。伯内特氏菌dot/icm位点的转座子插入突变首次揭示了IV型分泌是C.本发明的目的在于证实贝氏体在哺乳动物宿主细胞内的复制，并且效应物的递送需要Dot/Icm功能。因此，本研究结论性地表明，C。Burnetii Dot/Icm系统是细胞内复制的重要决定因素，并鉴定了具有该系统递送的新功能的独特效应蛋白的库，这些功能可能对疾病表型很重要。
Coxiella burnetii, the causative agent of human Q fever, is an intracellular pathogen that replicates in an acidified vacuole derived from the host lysosomal network. This pathogen encodes a Dot/Icm type IV secretion system that delivers bacterial proteins called effectors to the host cytosol. To identify new effector proteins, the functionally analogous Legionella pneumophila Dot/Icm system was used in a genetic screen to identify fragments of C. burnetii genomic DNA that when fused to an adenylate cyclase reporter were capable of directing Dot/Icm-dependent translocation of the fusion protein into mammalian host cells. This screen identified Dot/Icm effectors that were proteins unique to C. burnetii, having no overall sequence homology with L. pneumophila Dot/Icm effectors. A comparison of C. burnetii genome sequences from different isolates revealed diversity in the size and distribution of the genes encoding many of these effectors. Studies examining the localization and function of effectors in eukaryotic cells provided evidence that several of these proteins have an affinity for specific host organelles and can disrupt cellular functions. The identification of a transposon insertion mutation that disrupts the dot/icm locus was used to validate that this apparatus was essential for translocation of effectors. Importantly, this C. burnetii Dot/Icm-deficient mutant was found to be defective for intracellular replication. Thus, these data indicate that C. burnetii encodes a unique subset of bacterial effector proteins translocated into host cells by the Dot/Icm apparatus, and that the cumulative activities exerted by these effectors enables C. burnetii to successfully establish a niche inside mammalian cells that supports intracellular replication. Coxiella burnetii is a Gram-negative intracellular bacterium that can cause the human disease Q fever. A type IV secretion system in C. burnetii called Dot/Icm is functionally similar to the Dot/Icm system of Legionella pneumophila. Here we used L. pneumophila to screen a C. burnetii library for genes encoding effector proteins. We identified 18 effectors that are unique to C. burnetii and show that when they are expressed in eukaryotic cells they localize to specific compartments and can mediate changes in host cell physiology. Comparative genomic analysis revealed plasticity among these novel effector proteins that could be related to the different manifestations of disease exhibited by these clinical isolates of C. burnetii. A transposon insertion mutation in the dot/icm locus revealed for the first time that type IV secretion is essential for C. burnetii replication inside mammalian host cells and that the delivery of effectors requires Dot/Icm function. Thus, this study conclusively shows that the C. burnetii Dot/Icm system is an essential determinant for intracellular replication, and identifies a repertoire of unique effector proteins with novel functions delivered by this system that could be important for disease phenotypes.
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影响因子：
3.4
作者：
Heidtman M;Chen EJ;Moy MY;Isberg RR
通讯作者：
Isberg RR
影响因子：
3.4
作者：
Howe, D;Melnicáková, J;Heinzen, RA
通讯作者：
Heinzen, RA
影响因子：
56.9
作者：
JOINER, KA;FUHRMAN, SA;MELLMAN, I
通讯作者：
MELLMAN, I
DOI：
10.1073/pnas.78.5.3240
发表时间：
1981-01-01
期刊：
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA-BIOLOGICAL SCIENCES
影响因子：
--
作者：
HACKSTADT, T;WILLIAMS, JC
通讯作者：
WILLIAMS, JC
影响因子：
2.8
作者：
Cirillo, SLG;Lum, J;Cirillo, JD
通讯作者：
Cirillo, JD