7c76
Cryo-EM structure of human TLR3 in complex with UNC93B1
Structural highlights
DiseaseTLR3_HUMAN Defects in TLR3 are associated with herpes simplex encephalitis type 2 (HSE2) [MIM:613002. HSE is a rare complication of human herpesvirus 1 (HHV-1) infection, occurring in only a small minority of HHV-1 infected individuals. HSE is characterized by hemorrhagic necrosis of parts of the temporal and frontal lobes. Onset is over several days and involves fever, headache, seizures, stupor, and often coma, frequently with a fatal outcome. Note=TLR3 mutations predispose otherwise healthy individuals to isolated herpes simplex encephalitis through a mechanism that involves impaired IFNs production and reduced immune defense against viral infection in the central nervous system.[1] FunctionTLR3_HUMAN Key component of innate and adaptive immunity. TLRs (Toll-like receptors) control host immune response against pathogens through recognition of molecular patterns specific to microorganisms. TLR3 is a nucleotide-sensing TLR which is activated by double-stranded RNA, a sign of viral infection. Acts via MYD88 and TRAF6, leading to NF-kappa-B activation, cytokine secretion and the inflammatory response.[2] [3] [4] [5] [6] [7] Publication Abstract from PubMedNucleic acid-sensing Toll-like receptors (TLRs) play a pivotal role in innate immunity by recognizing foreign DNA and RNA. Compartmentalization of these TLRs in the endosome limits their activation by self-derived nucleic acids and reduces the possibility of autoimmune reactions. Although chaperone Unc-93 homolog B1, TLR signaling regulator (UNC93B1) is indispensable for the trafficking of TLRs from the endoplasmic reticulum to the endosome, mechanisms of UNC93B1-mediated TLR regulation remain largely unknown. Here, we report two cryo-EM structures of human and mouse TLR3-UNC93B1 complexes and a human TLR7-UNC93B1 complex. UNC93B1 exhibits structural similarity to the major facilitator superfamily transporters. Both TLRs interact with the UNC93B1 amino-terminal six-helix bundle through their transmembrane and luminal juxtamembrane regions, but the complexes of TLR3 and TLR7 with UNC93B1 differ in their oligomerization state. The structural information provided here should aid in designing compounds to combat autoimmune diseases. Cryo-EM structures of Toll-like receptors in complex with UNC93B1.,Ishida H, Asami J, Zhang Z, Nishizawa T, Shigematsu H, Ohto U, Shimizu T Nat Struct Mol Biol. 2021 Feb;28(2):173-180. doi: 10.1038/s41594-020-00542-w. , Epub 2021 Jan 11. PMID:33432245[8] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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