6s5t
Legionella pneumophila SidJ-Human calmodulin complex
Structural highlights
FunctionSIDJ_LEGPH Glutamylase that mediates the covalent attachment of glutamate moieties to SdeA on one of the catalytic residues that is required for its mono-ADP-ribosyltransferase activity (PubMed:31330532, PubMed:31330531). In turn, inhibits SdeA ubiquitinating activity. Glutamylates also related SdeB, SdeC and SidE (PubMed:31330531, PubMed:31123136). Glutamylase activity only occurs in the host since it requires host calmodulin (PubMed:28497808, PubMed:31330532, PubMed:31330531, PubMed:31123136). May also reverse the SdeA-mediated substrate ubiquitination by cleaving the phosphodiester bond that links phosphoribosylated ubiquitin to protein substrates via its deubiquitinase activity (PubMed:28497808).[1] [2] [3] [4] Publication Abstract from PubMedThe family of bacterial SidE enzymes catalyses phosphoribosyl-linked (PR) serine ubiquitination and promotes infectivity of Legionella pneumophilia, a pathogenic bacterium causing Legionnaires' disease(1-3). SidEs share the genetic locus with the Legionella effector SidJ that spatiotemporally opposes their toxicity in yeast and mammalian cells, through an unknown mechanism(4-6). Deletion of SidJ leads to a significant defect in the growth of Legionella in both its natural host amoeba and in murine macrophages(4,5). Here, we demonstrate that SidJ is a glutamylase that modifies the catalytic glutamate in the mono-ADPribosyl transferase (mART) domain of SdeA thus blocking its ubiquitin (Ub) ligase activity. SidJ glutamylation activity requires interaction with calmodulin (CaM), a eukaryotic specific co-factor, and can be regulated by intracellular changes in Ca(2+) concentrations. The cryo-EM structure of SidJ/human apo-CaM complex revealed the architecture of this unique heterodimeric glutamylase. In infected cells, we show that SidJ mediates glutamylation of SidEs on the surface of Legionella-containing vacuoles (LCVs). Using quantitative proteomics, we also uncovered multiple host proteins as putative targets of SidJ-mediated glutamylation. Collectively, this study reveals the mechanism of SidE ligases inhibition by a SidJ/CaM glutamylase and opens new avenues for studying protein glutamylation, an understudied protein modification in higher eukaryotes. Inhibition of bacterial ubiquitin ligases by SidJ-calmodulin-catalysed glutamylation.,Bhogaraju S, Bonn F, Mukherjee R, Adams M, Pfleiderer MM, Galej WP, Matkovic V, Lopez-Mosqueda J, Kalayil S, Shin D, Dikic I Nature. 2019 Jul 22. pii: 10.1038/s41586-019-1440-8. doi:, 10.1038/s41586-019-1440-8. PMID:31330532[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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