The intracellular bacterial pathogen Legionella pneumophila uses many effector proteins delivered by the bacterial type IV secretion system (T4SS) to hijack the early secretory pathway to establish its replicative niche, known as the Legionella-containing vacuole (LCV). On LCV biogenesis, the endoplasmic reticulum (ER) vesicular soluble N-ethylmaleimide-sensitive factor attachment protein receptors (v-SNARE) Sec22b is recruited to the bacterial phagosome and forms non-canonical pairings with target membrane SNAREs (t-SNAREs) from the plasma membrane. Here, we identify a Legionella deubiquitinase (DUB), LotB, that can modulate the early secretory pathway by interacting with coatomer protein complex I (COPI) vesicles when ectopically expressed. We show that Sec22b is ubiquitinated upon L. pneumophila infection in a T4SS-dependent manner and that, subsequently, LotB deconjugates K63-linked ubiquitins from Sec22b. The DUB activity of LotB stimulates dissociation of the t-SNARE syntaxin 3 (Stx3) from Sec22b, which resides on the LCV. Our study highlights a bacterial strategy manipulating the dynamics of infection-induced SNARE pairing using a bacterial DUB.

细胞内细菌病原体肺炎军团菌使用细菌IV型分泌系统（T4SS）传递的许多效应蛋白来劫持早期分泌途径，以建立其复制位，即含军团菌的液泡（LCV）。在LCV生物发生中，内质网（ER）囊泡可溶性N-乙基马来酰亚胺敏感因子附着蛋白受体（v-SNARE）Sec22b被募集到细菌吞噬体，并与靶膜SNARE（t-SNARE）形成非经典配对。质膜。在这里，我们确定了军团菌去泛素化酶（DUB），LotB，可在异位表达时通过与外壳蛋白复合物I（COPI）囊泡相互作用来调节早期分泌途径。我们表明，Sec22b是在泛素化的嗜肺军团菌在T4SS依赖性感染的是，随后，LotB从Sec22b deconjugates K63连接的泛素。LotB的DUB活性刺激t-SNARE语法3（Stx3）与Sec22b分离，后者位于LCV上。我们的研究突出了一种细菌策略，该策略利用细菌DUB操纵感染诱导的SNARE配对的动力学。