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3vq2

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Crystal structure of mouse TLR4/MD-2/LPS complex

Structural highlights

3vq2 is a 4 chain structure with sequence from Mus musculus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	X-ray diffraction, Resolution 2.48Å
Ligands:	, , , ,
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Disease

TLR4_MOUSE Note=The protein is encoded by the Lps locus, an important susceptibility locus, influencing the propensity to develop a disseminated Gram-negative infection.

Function

TLR4_MOUSE Cooperates with LY96 and CD14 to mediate the innate immune response to bacterial lipopolysaccharide (LPS). Acts via MYD88, TIRAP and TRAF6, leading to NF-kappa-B activation, cytokine secretion and the inflammatory response (By similarity).^[1]

Publication Abstract from PubMed

Lipopolysaccharide (LPS), also known as endotoxin, activates the innate immune response through toll-like receptor 4 (TLR4) and its coreceptor, MD-2. MD-2 has a unique hydrophobic cavity that directly binds to lipid A, the active center of LPS. Tetraacylated lipid IVa, a synthetic lipid A precursor, acts as a weak agonist to mouse TLR4/MD-2, but as an antagonist to human TLR4/MD-2. However, it remains unclear as to how LPS and lipid IVa show agonistic or antagonistic activities in a species-specific manner. The present study reports the crystal structures of mouse TLR4/MD-2/LPS and TLR4/MD-2/lipid IVa complexes at 2.5 and 2.7 A resolutions, respectively. Mouse TLR4/MD-2/LPS exhibited an agonistic "m"-shaped 2:2:2 complex similar to the human TLR4/MD-2/LPS complex. Mouse TLR4/MD-2/lipid IVa complex also showed an agonistic structural feature, exhibiting architecture similar to the 2:2:2 complex. Remarkably, lipid IVa in the mouse TLR4/MD-2 complex occupied nearly the same space as LPS, although lipid IVa lacked the two acyl chains. Human MD-2 binds lipid IVa in an antagonistic manner completely differently from the way mouse MD-2 does. Together, the results provide structural evidence of the agonistic property of lipid IVa on mouse TLR4/MD-2 and deepen understanding of the ligand binding and dimerization mechanism by the structurally diverse LPS variants.

Structural basis of species-specific endotoxin sensing by innate immune receptor TLR4/MD-2.,Ohto U, Fukase K, Miyake K, Shimizu T Proc Natl Acad Sci U S A. 2012 Apr 24. PMID:22532668^[2]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Rhee SH, Hwang D. Murine TOLL-like receptor 4 confers lipopolysaccharide responsiveness as determined by activation of NF kappa B and expression of the inducible cyclooxygenase. J Biol Chem. 2000 Nov 3;275(44):34035-40. PMID:10952994 doi:10.1074/jbc.M007386200
↑ Ohto U, Fukase K, Miyake K, Shimizu T. Structural basis of species-specific endotoxin sensing by innate immune receptor TLR4/MD-2. Proc Natl Acad Sci U S A. 2012 Apr 24. PMID:22532668 doi:10.1073/pnas.1201193109