PDF(Pubmed)
Abstract：
ADP-ribosylation is a reversible post-translational modification involved in various cellular activities. Removal of ADP-ribosylation requires (ADP-ribosyl)hydrolases, with macrodomain enzymes being a major family in this category. The pathogen Legionella pneumophila mediates atypical ubiquitination of host targets using the SidE effector family in a process that involves ubiquitin ADP-ribosylation on arginine 42 as an obligatory step. Here, we show that the Legionella macrodomain effector MavL regulates this pathway by reversing the arginine ADP-ribosylation, likely to minimize potential detrimental effects caused by the modified ubiquitin. We determine the crystal structure of ADP-ribose-bound MavL, providing structural insights into recognition of the ADP-ribosyl group and catalytic mechanism of its removal. Further analyses reveal DUF4804 as a class of MavL-like macrodomain enzymes whose representative members show unique selectivity for mono-ADP-ribosylated arginine residue in synthetic substrates. We find such enzymes are also present in eukaryotes, as exemplified by two previously uncharacterized (ADP-ribosyl)hydrolases in Drosophila melanogaster. Crystal structures of several proteins in this class provide insights into arginine specificity and a shared mode of ADP-ribose interaction distinct from previously characterized macrodomains. Collectively, our study reveals a new regulatory layer of SidE-catalyzed ubiquitination and expands the current understanding of macrodomain enzymes.
摘要：
ADP-核糖基化是涉及各种细胞活动的可逆翻译后修饰。去除ADP-核糖基化需要（ADP-核糖基）水解酶，巨域酶是这一类中的一个主要家族。病原体嗜肺军团菌使用SidE效应子家族介导宿主靶标的非典型泛素化，该过程涉及精氨酸42上的泛素ADP-核糖基化作为强制性步骤。这里,我们表明军团菌巨域效应物MavL通过逆转精氨酸ADP-核糖基化来调节该途径，可能会减少由修饰的泛素引起的潜在有害影响。我们确定了ADP-核糖结合的MavL的晶体结构，提供对ADP-核糖基的识别及其去除的催化机理的结构见解。进一步的分析揭示了DUF4804是一类MavL样巨域酶，其代表成员对合成底物中的单ADP-核糖基化精氨酸残基显示出独特的选择性。我们发现这种酶也存在于真核生物中，例如果蝇中两种先前未表征的（ADP-核糖基）水解酶。该类中几种蛋白质的晶体结构提供了对精氨酸特异性和ADP-核糖相互作用的共享模式的见解，该模式不同于先前表征的宏观结构域。总的来说，我们的研究揭示了SidE催化的泛素化的一个新的调控层,并扩展了目前对大结构域酶的理解.
