A Single Amino Acid of Toll-like Receptor 4 That Is Pivotal for Its Signal Transduction and Subcellular Localization

Shintaro Yanagimoto,Keita Tatsuno,Shu Okugawa,Takatoshi Kitazawa,Kunihisa Tsukada,Kazuhiko Koike,Tatsuhiko Kodama,Satoshi Kimura,Yoshikazu Shibasaki,Yasuo Ota

doi:10.1074/jbc.m803086200

Abstract

Toll-like receptor 4 (TLR4) is essential for recognizing a Gram-negative bacterial component, lipopolysaccharide (LPS). A single amino acid mutation at position 712 of murine TLR4 leads to hyporesponsiveness to LPS. In this study we determined that an amino acid, a leucine at position 815 of human TLR4, is also pivotal for LPS responsiveness and subcellular distribution. By replacing the leucine with alanine, the mutant TLR4 lost responsiveness to LPS and did not localize on the plasma membrane. In addition, it does not coprecipitate with myeloid differentiation-2, an accessory protein that is necessary for TLR4 to recognize LPS. These results suggest that the leucine at position 815 is required for the normal maturation of TLR4 and for formation of the TLR4.MD-2 complex.

Highlights

Toll-like receptors (TLRs)3 play essential roles in both innate and adaptive immunity [1]
The wild-type Toll-like receptor 4 (TLR4) cotransfected with sequences in the cytoplasmic tail of TLR4 that are involved in myeloid differentiation-2 (MD-2) was expressed on the plasma membrane and in the FEBRUARY 6, 2009
MD-2 is reported to be necessary for localization of wild-type TLR4 at the plasma membrane [15], which is consistent with our observation

Summary

Introduction

Toll-like receptors (TLRs)3 play essential roles in both innate and adaptive immunity [1]. By replacing the leucine with alanine, the mutant TLR4 lost responsiveness to LPS and did not localize on the plasma membrane. The wild-type TLR4 cotransfected with sequences in the cytoplasmic tail of TLR4 that are involved in MD-2 was expressed on the plasma membrane and in the FEBRUARY 6, 2009

Results

Conclusion