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J Biol Chem. 2012 Nov 23;287(48):40611-7. doi: 10.1074/jbc.M112.404608. Epub 2012 Oct 10.

Structural analyses of human Toll-like receptor 4 polymorphisms D299G and T399I.

Author information

1
Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Tokyo 113-0033, Japan.

Abstract

BACKGROUND:

TLR4 polymorphism replacing Asp-299 with Gly and Thr-399 with Ile (D299G/T399I) causes LPS hyporesponsiveness.

RESULTS:

TLR4(SNPs)·MD-2·LPS exhibits an agonistic 2:2:2 architecture. Local structural differences were observed around D299G, but not around T399I, SNP site.

CONCLUSION:

These local differences cause the modulation of surface properties of TLR4, which may affect ligand binding.

SIGNIFICANCE:

This study provides structural evidence of the functionality of the mutant TLR4 carrying the SNPs. Toll-like receptor 4 (TLR4) and its coreceptor MD-2 recognize bacterial lipopolysaccharide (LPS) and signal the innate immune response. Two single nucleotide polymorphisms (SNPs) of human TLR4, D299G and T399I, have been identified and suggested to be associated with LPS hyporesponsiveness. Moreover, the SNPs have been proposed to be associated with a variety of infectious and noninfectious diseases. However, how the SNPs affect the function of TLR4 remains largely unknown. Here, we report the crystal structure of the human TLR4 (D299G/T399I)·MD-2·LPS complex at 2.4 Å resolution. The ternary complex exhibited an agonistic "m"-shaped 2:2:2 architecture that was similar to that of the human wild type TLR4·MD-2·LPS complex. Local structural differences that might affect the binding of the ligands were observed around D299G, but not around T399I, SNP site.

PMID:
23055527
PMCID:
PMC3504774
DOI:
10.1074/jbc.M112.404608
[Indexed for MEDLINE]
Free PMC Article

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