Mechanism of Lys6 poly-ubiquitin specificity by the L. pneumophila deubiquitinase LotA

Unexpected functional and structural diversity in deubiquitinases of the Chlamydia-like bacterium Simkania negevensis

“…First, it should be emphasized that the M1 and K6 speci c activities in Legionella and Simkania arose through convergent evolution. The K6-speci c DUB of L. pneumophila (LotA) 23,24 belongs to the OTU family, which is known to comprise mostly linkagespeci c or -selective activities 57 . By contrast, the K6-speci c DUB of S. negevensis (SnVTD) belongs to the recently discovered VTD-family, which is unrelated to OTUs but ful lls similar roles in viruses and transposons 31 .…”

“…Most intracellular bacteria code for one, sometimes two DUB effectors, which typically show little linkage speci city. By contrast, L. pneumophila is unique among characterized bacteria in that it encodes multiple DUBs 20,21 , including the linear chain (M1)-speci c RavD 22 and the K6-speci c LotA 23,24 . The majority of bacterial DUBs belong to two different protease families: the OTU (ovarian-tumor related) family known for eukaryotic linkage-speci c DUBs 25 , and the CE-clan, whose eukaryotic members are proteases for ubiquitin-like modi ers, but no DUBs 26 .…”

Ubiquitin‐targeted bacterial effectors: rule breakers of the ubiquitin system

“…A family of related Legionella OTU (LOT) DUBs has recently been identified by sequence homology (Pruneda et al , 2023). The first example, LotA (lpg2248), contains two active OTU‐like domains, the first of which is capable of hydrolyzing K6‐linked polyUb, while the second appears to prefer longer K48‐linked and K63‐linked polyUb chains (Kubori et al , 2018; Luo et al , 2022; Takekawa et al , 2022; Kang et al , 2023; Warren et al , 2023). Interestingly, only the second LotA OTU domain appears to be important for Legionella growth in mouse bone marrow‐derived macrophages, although only in a background where the SidE family ligases are deleted.…”

“…Interestingly, only the second LotA OTU domain appears to be important for Legionella growth in mouse bone marrow‐derived macrophages, although only in a background where the SidE family ligases are deleted. LotA was shown to localize to the outside of the LCV, where its dual DUB activities act to edit the coat of ubiquitin modifications and function to restrict localization of the AAA ATPase VCP (Kubori et al , 2018; Warren et al , 2023). The related LOT DUBs, LotB (lpg1621) and LotC (lpg2529), have also been shown to localize to the LCV in order to edit the ubiquitin coat (Liu et al , 2020; Ma et al , 2020; Shi et al , 2023a).…”

“…Interestingly, a structural relationship has recently been established between the LOT insertion domains and a related Ub‐binding domain from a DUB encoded by Orientia tsutsugamushi . This domain adapts Ub‐binding sites within a variable region of an otherwise common fold, and was therefore named an “adaptive Ub‐binding domain” (A‐UBD; Warren et al , 2023).…”