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From Proteopedia
Cryo-EM structure of SidJ-SdeA-CaM reaction intermediate 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:31330531, PubMed:31330532). In turn, inhibits SdeA ubiquitinating activity. Glutamylates also related SdeB, SdeC and SidE (PubMed:31123136, PubMed:31330531). Glutamylase activity only occurs in the host since it requires host calmodulin (PubMed:28497808, PubMed:31123136, PubMed:31330531, PubMed:31330532). 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 kinase domain transfers phosphate from ATP to substrates. However, the Legionella effector SidJ adopts a kinase fold, yet catalyzes calmodulin (CaM)-dependent glutamylation to inactivate the SidE ubiquitin ligases. The structural and mechanistic basis in which the kinase domain catalyzes protein glutamylation is unknown. Here we present cryo-EM reconstructions of SidJ:CaM:SidE reaction intermediate complexes. We show that the kinase-like active site of SidJ adenylates an active-site Glu in SidE, resulting in the formation of a stable reaction intermediate complex. An insertion in the catalytic loop of the kinase domain positions the donor Glu near the acyl-adenylate for peptide bond formation. Our structural analysis led us to discover that the SidJ paralog SdjA is a glutamylase that differentially regulates the SidE ligases during Legionella infection. Our results uncover the structural and mechanistic basis in which the kinase fold catalyzes non-ribosomal amino acid ligations and reveal an unappreciated level of SidE-family regulation. Structural and mechanistic basis for protein glutamylation by the kinase fold.,Osinski A, Black MH, Pawlowski K, Chen Z, Li Y, Tagliabracci VS Mol Cell. 2021 Nov 4;81(21):4527-4539.e8. doi: 10.1016/j.molcel.2021.08.007. Epub , 2021 Aug 17. PMID:34407442[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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