6ac5 | pdb_00006ac5
Crystal structure of RIPK1 death domain GlcNAcylated by EPEC effector NleB
Structural highlights
Function[RIPK1_HUMAN] Serine-threonine kinase which transduces inflammatory and cell-death signals (programmed necrosis) following death receptors ligation, activation of pathogen recognition receptors (PRRs), and DNA damage. Upon activation of TNFR1 by the TNF-alpha family cytokines, TRADD and TRAF2 are recruited to the receptor. Ubiquitination by TRAF2 via 'Lys-63'-link chains acts as a critical enhancer of communication with downstream signal transducers in the mitogen-activated protein kinase pathway and the NF-kappa-B pathway, which in turn mediate downstream events including the activation of genes encoding inflammatory molecules. Polyubiquitinated protein binds to IKBKG/NEMO, the regulatory subunit of the IKK complex, a critical event for NF-kappa-B activation. Interaction with other cellular RHIM-containing adapters initiates gene activation and cell death. RIPK1 and RIPK3 association, in particular, forms a necrosis-inducing complex.[1] [2] [3] Publication Abstract from PubMedEnteropathogenic E. coli NleB and related type III effectors catalyze arginine GlcNAcylation of death domain (DD) proteins to block host defense, but the underlying mechanism is unknown. Here we solve crystal structures of NleB alone and in complex with FADD-DD, UDP, and Mn(2+) as well as NleB-GlcNAcylated DDs of TRADD and RIPK1. NleB adopts a GT-A fold with a unique helix-pair insertion to hold FADD-DD; the interface contacts explain the selectivity of NleB for certain DDs. The acceptor arginine is fixed into a cleft, in which Glu253 serves as a base to activate the guanidinium. Analyses of the enzyme-substrate complex and the product structures reveal an inverting sugar-transfer reaction and a detailed catalytic mechanism. These structural insights are validated by mutagenesis analyses of NleB-mediated GlcNAcylation in vitro and its function in mouse infection. Our study builds a structural framework for understanding of NleB-catalyzed arginine GlcNAcylation of host death domain. Structural and Functional Insights into Host Death Domains Inactivation by the Bacterial Arginine GlcNAcyltransferase Effector.,Ding J, Pan X, Du L, Yao Q, Xue J, Yao H, Wang DC, Li S, Shao F Mol Cell. 2019 Apr 3. pii: S1097-2765(19)30232-1. doi:, 10.1016/j.molcel.2019.03.028. PMID:30979585[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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