Department of Microbiology, Graduate School of Medicine, Gifu University, Gifu, Gifu 501-1194, Japan.
Department of Microbiology, Graduate School of Medicine, Gifu University, Gifu, Gifu 501-1194, Japan; Laboratory of Veterinary Microbiology, Faculty of Applied Biological Science, Gifu University, Gifu, Gifu 501-1193, Japan.
Cell Rep. 2020 Sep 8;32(10):108107. doi: 10.1016/j.celrep.2020.108107.
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.
胞内细菌病原体嗜肺军团菌利用细菌 IV 型分泌系统（T4SS）输送的许多效应蛋白劫持早期分泌途径，从而建立其复制龛，即称为军团菌包含的空泡（LCV）。在 LCV 的生物发生过程中，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 被招募到细菌吞噬体，并与来自质膜的靶膜 SNARE（t-SNARE）形成非典型配对。在这里，我们鉴定了一种军团菌去泛素化酶（DUB）LotB，当异位表达时，它可以通过与衣壳蛋白复合物 I（COPI）囊泡相互作用来调节早期分泌途径。我们表明，Sec22b 在依赖 T4SS 的方式下在 L. 肺炎感染时被泛素化，随后，LotB 从 Sec22b 上除去 K63 连接的泛素。LotB 的 DUB 活性刺激驻留在 LCV 上的 t-SNARE 突触蛋白 3（Stx3）与 Sec22b 的解离。我们的研究强调了一种细菌策略，即利用细菌 DUB 操纵感染诱导的 SNARE 配对的动力学。
