Coxiella burnetii, the etiological agent of the zoonosis Q fever, replicates inside host cells within a large vacuole displaying autolysosomal characteristics. The development of this compartment is mediated by bacterial effectors, which interfere with a number of host membrane trafficking pathways. By screening a Coxiella transposon mutant library, we observed that transposon insertions in cbu0626 led to intracellular replication and vacuole biogenesis defects. Here, we demonstrate that CBU0626 is a novel member of the Coxiella vacuolar protein (Cvp) family of effector proteins, which is translocated by the Dot/Icm secretion system and localizes to vesicles with autolysosomal features as well as Coxiella-containing vacuoles (CCVs). We thus renamed this effector CvpF for Coxiella vacuolar protein F. CvpF specifically interacts with the host small GTPase RAB26, leading to the recruitment of the autophagosomal marker MAP1LC3B/LC3B (microtubule associated protein 1 light chain 3 beta) to CCVs. Importantly, cvpF::Tn mutants were highly attenuated compared to wild-type bacteria in the SCID mouse model of infection, highlighting the importance of CvpF for Coxiella virulence. These results suggest that CvpF manipulates endosomal trafficking and macroautophagy/autophagy induction for optimal C. burnetii vacuole biogenesis.Abbreviations: ACCM: acidified citrate cystein medium; AP: adaptor related protein complex; CCV: Coxiella-containing vacuole; Cvp: Coxiella vacuolar protein; GDI: guanosine nucleotide dissociation inhibitor; GDF: GDI dissociation factor; GEF: guanine exchange factor; LAMP1: lysosomal associated membrane protein 1; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; MTORC1: mechanistic target of rapamycin kinase MTOR complex 1; PBS: phosphate-buffered saline; PMA: phorbol myristate acetate; SQSTM1/p62: sequestosome 1; WT: wild-type.

中文翻译：

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Coxiella 效应蛋白 CvpF 颠覆 RAB26 依赖性自噬以促进液泡生物发生和毒力。

Coxiella burnetii 是人畜共患病 Q 热的病原体，它在宿主细胞内的一个大液泡内复制，显示出自溶酶体特征。该隔室的发育由细菌效应物介导，细菌效应物会干扰许多宿主膜运输途径。通过筛选 Coxiella 转座子突变文库，我们观察到 cbu0626 中的转座子插入导致细胞内复制和液泡生物发生缺陷。在这里，我们证明 CBU0626 是 Coxiella 液泡蛋白 (Cvp) 效应蛋白家族的新成员，它通过 Dot/Icm 分泌系统易位并定位于具有自溶酶体特征的囊泡以及含有 Coxiella 的液泡 (CCV) . 因此，我们将该效应子 CvpF 重命名为 Coxiella 液泡蛋白 F。CvpF 与宿主小 GTPase RAB26 特异性相互作用，导致自噬体标记物 MAP1LC3B/LC3B（微管相关蛋白 1 轻链 3 β）募集到 CCV。重要的是，与 SCID 小鼠感染模型中的野生型细菌相比，cvpF::Tn 突变体高度减毒，突出了 CvpF 对 Coxiella 毒力的重要性。这些结果表明 CvpF 操纵内体运输和巨自噬/自噬诱导，以获得最佳的 C.burnetii 液泡生物发生。缩写：ACCM：酸化柠檬酸盐半胱氨酸培养基；AP：接头相关蛋白复合物；CCV：含 Coxiella 的液泡；Cvp：Coxiella 液泡蛋白；GDI：鸟苷核苷酸解离抑制剂；GDF：GDI解离因子；GEF：鸟嘌呤交换因子；LAMP1：溶酶体相关膜蛋白 1；MAP1LC3B/LC3B：微管相关蛋白 1 轻链 3 β；MTORC1：雷帕霉素激酶 MTOR 复合物 1 的机制靶点；PBS：磷酸盐缓冲盐水；PMA：佛波肉豆蔻酸酯醋酸酯；SQSTM1/p62：sequestosome 1；WT：野生型。