Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul, Republic of Korea.
School of Biological Science, Institute of Molecular Biology and Genetics, Seoul National University, Seoul, Republic of Korea.
Life Sci Alliance. 2023 Apr 26;6(7). doi: 10.26508/lsa.202201876. Print 2023 Jul.
Although ubiquitin is found only in eukaryotes, several pathogenic bacteria and viruses possess proteins that hinder the host ubiquitin system. , a gram-negative intracellular bacterium, possesses an ovarian tumor (OTU) family of deubiquitinases (Lot DUBs). Herein, we describe the molecular characteristics of Lot DUBs. We elucidated the structure of the LotA OTU1 domain and revealed that entire Lot DUBs possess a characteristic extended helical lobe that is not found in other OTU-DUBs. The structural topology of an extended helical lobe is the same throughout the Lot family, and it provides an S1' ubiquitin-binding site. Moreover, the catalytic triads of Lot DUBs resemble those of the A20-type OTU-DUBs. Furthermore, we revealed a unique mechanism by which LotA OTU domains cooperate together to distinguish the length of the chain and preferentially cleave longer K48-linked polyubiquitin chains. The LotA OTU1 domain itself cleaves K6-linked ubiquitin chains, whereas it is also essential for assisting the cleavage of longer K48-linked polyubiquitin chains by the OTU2 domain. Thus, this study provides novel insights into the structure and mechanism of action of Lot DUBs.
虽然泛素仅存在于真核生物中，但几种致病性细菌和病毒都具有抑制宿主泛素系统的蛋白质。一种革兰氏阴性细胞内细菌，具有一个卵巢肿瘤（OTU）家族的去泛素化酶（Lot DUBs）。本文描述了 Lot DUBs 的分子特征。我们阐明了 LotA OTU1 结构域的结构，并揭示了整个 Lot DUBs 都具有一个特征性的扩展螺旋叶，而其他 OTU-DUBs 则没有。整个 Lot 家族的扩展螺旋叶的结构拓扑相同，它提供了一个 S1'泛素结合位点。此外，Lot DUBs 的催化三联体类似于 A20 型 OTU-DUBs 的催化三联体。此外，我们揭示了一种独特的机制，即 LotA OTU 结构域协同作用，以区分链的长度并优先切割更长的 K48 连接多泛素链。LotA OTU1 结构域本身可切割 K6 连接的泛素链，但其对于 OTU2 结构域协助切割更长的 K48 连接多泛素链也是必需的。因此，这项研究为 Lot DUBs 的结构和作用机制提供了新的见解。
