Effector protein translocation by the Coxiella burnetii Dot/Icm type IV secretion system requires endocytic maturation of the pathogen-occupied vacuole.
Effector protein translocation by the Coxiella burnetii Dot/Icm type IV secretion system requires endocytic maturation of the pathogen-occupied vacuole.
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DOI：
10.1371/journal.pone.0054566
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发表时间：
2013
期刊：
影响因子：
3.7
通讯作者：
Roy CR
中科院分区：
文献类型：
--
作者：
Newton HJ;McDonough JA;Roy CR
人类病原体伯氏柯克斯体编码一种称为 Dot/Icm 的 IV 型分泌系统，该系统对于细胞内复制至关重要。 Dot/Icm 系统在感染过程中将细菌效应蛋白递送到宿主细胞质中。据预测，伯氏念珠菌递送的效应蛋白在感染过程中具有重要功能，但在感染过程中何时需要这些蛋白尚未明确定义。在这里，我们使用由融合蛋白组成的报告系统来研究 Dot/Icm 系统的蛋白质易位，该融合蛋白将 β-内酰胺酶 (BlaM) 与伯内特氏菌效应蛋白融合。直到 HeLa 细胞感染后 8 小时才检测到与效应蛋白 CBU0077、CBU1823 和 CBU1524 融合的 BlaM 的易位，而 HeLa 细胞允许伯氏梭菌复制。 Dot/Icm 系统对这些效应融合蛋白的易位需要对含有柯克斯体的液泡进行酸化。编码膜转运调节因子 Rab5 或 Rab7 的宿主基因的沉默会干扰效应子易位，这表明效应子在细菌运输到宿主细胞中的晚期内吞区室之前不会易位。在源自 C57BL/6 小鼠的骨髓巨噬细胞中也发现了对效应器易位的类似要求，这些巨噬细胞是限制伯氏梭菌细胞内复制的主要细胞。除了 Dot/Icm 介导的效应器易位需要液泡的内吞成熟之外，该过程还需要细菌转录。因此，C.burnetii Dot/Icm 系统效应蛋白的易位发生在 CCV 酸化和这种特殊细胞器成熟到晚期内吞区室之后。这表明，伯氏梭菌在其中复制的特化液泡的产生代表了一个两阶段过程，最初由调节内吞成熟的宿主因子介导，然后在细菌在溶酶体衍生的细胞器中建立驻留后，由细菌效应物传递到宿主细胞中。
The human pathogen Coxiella burnetii encodes a type IV secretion system called Dot/Icm that is essential for intracellular replication. The Dot/Icm system delivers bacterial effector proteins into the host cytosol during infection. The effector proteins delivered by C. burnetii are predicted to have important functions during infection, but when these proteins are needed during infection has not been clearly defined. Here, we use a reporter system consisting of fusion proteins that have a β-lactamase enzyme (BlaM) fused to C. burnetii effector proteins to study protein translocation by the Dot/Icm system. Translocation of BlaM fused to the effector proteins CBU0077, CBU1823 and CBU1524 was not detected until 8-hours after infection of HeLa cells, which are permissive for C. burnetii replication. Translocation of these effector fusion proteins by the Dot/Icm system required acidification of the Coxiella-containing vacuole. Silencing of the host genes encoding the membrane transport regulators Rab5 or Rab7 interfered with effector translocation, which indicates that effectors are not translocated until bacteria traffic to a late endocytic compartment in the host cell. Similar requirements for effector translocation were discerned in bone marrow macrophages derived from C57BL/6 mice, which are primary cells that restrict the intracellular replication of C. burnetii. In addition to requiring endocytic maturation of the vacuole for Dot/Icm-mediated translocation of effectors, bacterial transcription was required for this process. Thus, translocation of effector proteins by the C. burnetii Dot/Icm system occurs after acidification of the CCV and maturation of this specialized organelle to a late endocytic compartment. This indicates that creation of the specialized vacuole in which C. burnetii replicates represents a two-stage process mediated initially by host factors that regulate endocytic maturation and then by bacterial effectors delivered into host cells after bacteria establish residency in a lysosome-derived organelle.
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影响因子：
6.4
作者：
Beare PA;Gilk SD;Larson CL;Hill J;Stead CM;Omsland A;Cockrell DC;Howe D;Voth DE;Heinzen RA
通讯作者：
Heinzen RA
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：
6.7
作者：
Carey KL;Newton HJ;Lührmann A;Roy CR
通讯作者：
Roy CR
DOI：
10.1007/978-94-007-4315-1_13
发表时间：
2012-01-01
期刊：
COXIELLA BURNETII: RECENT ADVANCES AND NEW PERSPECTIVES IN RESEARCH OF THE Q FEVER BACTERIUM
影响因子：
--
作者：
Beare, Paul A.
通讯作者：
Beare, Paul A.
DOI：
10.1073/pnas.0812074106
发表时间：
2009-03-17
影响因子：
11.1
作者：
Omsland, Anders;Cockrell, Diane C.;Heinzen, Robert A.
通讯作者：
Heinzen, Robert A.