4dom
From Proteopedia
Crystal Structure of the TIR-domain of Human Myeloid Differentiation Primary Response protein (MyD88)
Structural highlights
Disease[MYD88_HUMAN] Defects in MYD88 are the cause of MYD88 deficiency (MYD88D) [MIM:612260]; also known as recurrent pyogenic bacterial infections due to MYD88 deficiency. Patients suffer from autosomal recessive, life-threatening, often recurrent pyogenic bacterial infections, including invasive pneumococcal disease, and die between 1 and 11 months of age. Surviving patients are otherwise healthy, with normal resistance to other microbes, and their clinical status improved with age.[1] [2] Function[MYD88_HUMAN] Adapter protein involved in the Toll-like receptor and IL-1 receptor signaling pathway in the innate immune response. Acts via IRAK1, IRAK2, IRF7 and TRAF6, leading to NF-kappa-B activation, cytokine secretion and the inflammatory response. Increases IL-8 transcription. Involved in IL-18-mediated signaling pathway. Activates IRF1 resulting in its rapid migration into the nucleus to mediate an efficient induction of IFN-beta, NOS2/INOS, and IL12A genes (By similarity).[3] [4] [5] [6] Publication Abstract from PubMedThe Toll/IL-1 receptor (TIR) domains are crucial signaling modules during innate immune responses involving the Toll-like receptors (TLRs) and IL-1 receptor (IL-1R). Myeloid differential factor 88 (MyD88) is a central TIR domain-containing adapter molecule responsible for nearly all TLR-mediated signaling and is targeted by a TIR domain-containing protein C (TcpC) from virulent uropathogenic Escherichia coli, a common human pathogen. The mechanism of such molecular antagonism has remained elusive. We present the crystal structure of the MyD88 TIR domain with distinct loop conformations that underscore the functional specialization of the adapter, receptor, and microbial TIR domains. Our structural analyses shed light on the genetic mutations at these loops as well as the Poc site. We demonstrate that TcpC directly associates with MyD88 and TLR4 through its predicted DD and BB loops to impair the TLR-induced cytokine induction. Furthermore, NMR titration experiments identify the unique CD, DE, and EE loops from MyD88 at the TcpC-interacting surface, suggesting that TcpC specifically engages these MyD88 structural elements for immune suppression. These findings thus provide a molecular basis for the subversion of TLR signaling by the uropathogenic E. coli virulence factor TcpC and furnish a framework for the design of novel therapeutic agents that modulate immune activation. Molecular mechanisms for the subversion of MyD88 signaling by TcpC from virulent uropathogenic Escherichia coli.,Snyder GA, Cirl C, Jiang J, Chen K, Waldhuber A, Smith P, Rommler F, Snyder N, Fresquez T, Durr S, Tjandra N, Miethke T, Xiao TS Proc Natl Acad Sci U S A. 2013 Apr 8. PMID:23569230[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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