Wan Min, Minelli Marena E, Zhao Qiuye, Marshall Shannon, Yu Haiyuan, Smolka Marcus, Mao Yuxin
Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA.
Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA.
Res Sq. 2023 Sep 14:rs.3.rs-3266941. doi: 10.21203/rs.3.rs-3266941/v1.
Ubiquitination is a crucial posttranslational modification in eukaryotes that plays a significant role in the infection of intracellular microbial pathogens, such as the bacterium responsible for Legionnaires' disease. While the -containing vacuole (LCV) is coated with ubiquitin (Ub), it avoids recognition by autophagy adaptors. In this study, we report that the Sdc and Sde families of effectors work together to build ubiquitinated species around the LCV. The Sdc effectors catalyze canonical polyubiquitination directly on host targets or on the phosphoribosyl-Ub (PR-Ub) conjugated to host targets by Sde. Remarkably, the Ub moieties within the poly-Ub chains are either modified with a phosphoribosyl group by Sde and other PDE domain-containing effectors or covalently attached to other host substrates via Sde-mediated PR-ubiquitination. Furthermore, these modifications prevent the recognition by Ub adaptors, such as p62, and therefore exclude host autophagy adaptors from the LCV. Our findings shed light on the nature of the poly-ubiquitinated species present at the surface of the LCV and provide a molecular mechanism for the avoidance of autophagy adaptors by the Ub-decorated LCV.
泛素化是真核生物中一种关键的翻译后修饰，在细胞内微生物病原体（如引起军团病的细菌）的感染过程中发挥着重要作用。虽然含军团菌的液泡（LCV）被泛素（Ub）包裹，但它能避免被自噬衔接蛋白识别。在本研究中，我们报告效应子的Sdc和Sde家族共同作用，在LCV周围构建泛素化物质。Sdc效应子直接在宿主靶标上或在由Sde与宿主靶标结合的磷酸核糖基泛素（PR-Ub）上催化典型的多聚泛素化。值得注意的是，多聚泛素链中的Ub部分要么被Sde和其他含PDE结构域的效应子用磷酸核糖基修饰，要么通过Sde介导的PR-泛素化共价连接到其他宿主底物上。此外，这些修饰阻止了Ub衔接蛋白（如p62）的识别，从而将宿主自噬衔接蛋白排除在LCV之外。我们的研究结果揭示了LCV表面存在的多聚泛素化物质的本质，并为Ub修饰的LCV避免自噬衔接蛋白提供了一种分子机制。
