A unique deubiquitinase that deconjugates phosphoribosyl-linked protein ubiquitination

• Published in: Cell research 2017-07, Vol.27 (7), p.865-881
• Main Authors: Qiu, Jiazhang, Yu, Kaiwen, Fei, Xiaowen, Liu, Yao, Nakayasu, Ernesto S, Piehowski, Paul D, Shaw, Jared B, Puvar, Kedar, Das, Chittaranjan, Liu, Xiaoyun, Luo, Zhao-Qing
• Format: Article
• Language: English
• Subjects: 60 APPLIED LIFE SCIENCES; 631/250/255/1318; 631/45/607/1164; 631/80/458/582; 631/80/86; Abundance; Adenosine diphosphate; ADP-ribosylation; Animals; Bacteria; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Bacterial Secretion Systems; BASIC BIOLOGICAL SCIENCES; Biomedical and Life Sciences; Cascades; Catalysis; Cell Biology; Cercopithecus aethiops; COS Cells; Cysteine; Cysteine - metabolism; Deubiquitinating Enzymes - genetics; Deubiquitinating Enzymes - metabolism; Effectors; Endoplasmic reticulum; Environmental Molecular Sciences Laboratory; Enzymes; Female; HEK293 Cells; Humans; Immunity; Legionella pneumophila - enzymology; Legionnaires' disease bacterium; Life Sciences; Machinery and equipment; Macrophages; Membrane Proteins - genetics; Membrane Proteins - metabolism; Mice; Original; original-article; Pathogens; Phosphodiesterase; Protein Processing, Post-Translational; Proteins; Residues; Ribosylation; Serine; Substrates; Ubiquitin; Ubiquitin - metabolism; Ubiquitination; Ubiquitination - physiology; Virulence Factors - genetics; Virulence Factors - metabolism
• ISSN: 1001-0602; 1748-7838
• DOI: 10.1038/cr.2017.66

Ubiquitination regulates many aspects of host immunity and thus is a common target for infectious agents. Recent studies have revealed that members of the SidE effector family of the bacterial pathogen Legionella pneumophila attack several small GTPases associated with the endoplasmic reticulum by a novel ubiquitination mechanism that does not require the E1 and E2 enzymes of the host ubiquitination machinery. In this case, ubiquitin is first activat- ed by ADP-ribosylation at Arg42 by a mono-ADP-ribosyltransferase activity; the intermediate is then cleaved by a phosphodiesterase activity also residing within SdeA, concomitant with the attachment of ubiquitin to serine residues of substrate proteins via a phosphoribosyl linker. Here we demonstrate that the effect of SidEs is antagonized by SidJ, an effector encoded by a gene situated in the locus coding for three members of the SidE family （SdeC, SdeB and SdeA）. SidJ reverses ubiquitination of SidEs-modified substrates by cleaving the phosphodiester bond that links phosphoribosylated ubiquitin to protein substrates. SidJ also displays classical deubiquitinase activity but does not require catalytic cysteine residues. Further, these deubiquitinase activities of SidJ are essential for its role in L. pneu- mophila infection. Finally, the activity of SidJ is required for efficiently reducing the abundance of ubiquitinated Rab33b in infected cells within a few hours after bacterial uptake. Our results establish SidJ as a ubiquitin-deconju- gating enzyme that functions to impose temporal regulation on the activity of SidE effectors. SidJ may be important in future studies of signaling cascades mediated by this unique ubiquitination, one that also potentially regulates cel- lular processes in eukaryotic cells.