7c76

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Cryo-EM structure of human TLR3 in complex with UNC93B1Cryo-EM structure of human TLR3 in complex with UNC93B1

Structural highlights

7c76 is a 2 chain structure with sequence from Homo sapiens. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:Electron Microscopy, Resolution 3.4Å
Ligands:,
Resources:FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Disease

TLR3_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]

Function

TLR3_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 PubMed

Nucleic 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 Also

References

  1. Zhang SY, Jouanguy E, Ugolini S, Smahi A, Elain G, Romero P, Segal D, Sancho-Shimizu V, Lorenzo L, Puel A, Picard C, Chapgier A, Plancoulaine S, Titeux M, Cognet C, von Bernuth H, Ku CL, Casrouge A, Zhang XX, Barreiro L, Leonard J, Hamilton C, Lebon P, Heron B, Vallee L, Quintana-Murci L, Hovnanian A, Rozenberg F, Vivier E, Geissmann F, Tardieu M, Abel L, Casanova JL. TLR3 deficiency in patients with herpes simplex encephalitis. Science. 2007 Sep 14;317(5844):1522-7. PMID:17872438 doi:317/5844/1522
  2. de Bouteiller O, Merck E, Hasan UA, Hubac S, Benguigui B, Trinchieri G, Bates EE, Caux C. Recognition of double-stranded RNA by human toll-like receptor 3 and downstream receptor signaling requires multimerization and an acidic pH. J Biol Chem. 2005 Nov 18;280(46):38133-45. Epub 2005 Sep 6. PMID:16144834 doi:M507163200
  3. Johnsen IB, Nguyen TT, Ringdal M, Tryggestad AM, Bakke O, Lien E, Espevik T, Anthonsen MW. Toll-like receptor 3 associates with c-Src tyrosine kinase on endosomes to initiate antiviral signaling. EMBO J. 2006 Jul 26;25(14):3335-46. Epub 2006 Jul 6. PMID:16858407 doi:7601222
  4. Bell JK, Askins J, Hall PR, Davies DR, Segal DM. The dsRNA binding site of human Toll-like receptor 3. Proc Natl Acad Sci U S A. 2006 Jun 6;103(23):8792-7. Epub 2006 May 23. PMID:16720699 doi:10.1073/pnas.0603245103
  5. Sarkar SN, Elco CP, Peters KL, Chattopadhyay S, Sen GC. Two tyrosine residues of Toll-like receptor 3 trigger different steps of NF-kappa B activation. J Biol Chem. 2007 Feb 9;282(6):3423-7. Epub 2006 Dec 18. PMID:17178723 doi:C600226200
  6. Leonard JN, Ghirlando R, Askins J, Bell JK, Margulies DH, Davies DR, Segal DM. The TLR3 signaling complex forms by cooperative receptor dimerization. Proc Natl Acad Sci U S A. 2008 Jan 8;105(1):258-63. doi: 10.1073/pnas.0710779105., Epub 2008 Jan 2. PMID:18172197 doi:10.1073/pnas.0710779105
  7. Bell JK, Botos I, Hall PR, Askins J, Shiloach J, Segal DM, Davies DR. The molecular structure of the Toll-like receptor 3 ligand-binding domain. Proc Natl Acad Sci U S A. 2005 Aug 2;102(31):10976-80. Epub 2005 Jul 25. PMID:16043704
  8. Ishida H, Asami J, Zhang Z, Nishizawa T, Shigematsu H, Ohto U, Shimizu T. Cryo-EM structures of Toll-like receptors in complex with UNC93B1. Nat Struct Mol Biol. 2021 Feb;28(2):173-180. PMID:33432245 doi:10.1038/s41594-020-00542-w

7c76, resolution 3.40Å

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