The extracellular toll-like receptor 2 domain directly binds peptidoglycan derived from Staphylococcus aureus
The extracellular toll-like receptor 2 domain directly binds peptidoglycan derived from Staphylococcus aureus
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DOI：
10.1074/jbc.m107057200
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发表时间：
2002-07-05
影响因子：
4.8
通讯作者：
Kuroki, Y
中科院分区：
文献类型：
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作者：
Iwaki, D;Mitsuzawa, H;Kuroki, Y
Toll样受体2(TLR2)是革兰氏阳性菌的主要细胞壁成分，在细胞信号转导中起重要作用。TLR2识别PGN的机制尚不清楚。甚至还不清楚TLR2是否直接与PGN结合。在本研究中，我们利用杆状病毒表达系统构建了一种可溶性形式的重组TLR2(STLR2)，它只具有其推测的胞外区，以检测sTLR2与PGN之间的直接相互作用。STLR2以浓度依赖的方式与包被在微滴定孔上的金黄色葡萄球菌的不溶性PGN(IPGN)结合。相反，sTLR2与脂多糖的结合很弱。IPGN与sTLR2的混合物孵育、离心后，IPGN与sTLR2共表达。STLR2可部分抑制IPGN诱导的HEK 293细胞的NF-kappaB活化和IPGN诱导的U937细胞分泌IL-8。抗人TLR2单抗可阻断IPGN诱导的TLR2细胞中核因子-kappaB的活化，抑制sTLR2与iPGN的结合。此外，我们还发现sCD14与sTLR2相互作用，并增加了sTLR2与iPGN的结合。根据这些结果，我们认为胞外TLR2结构域直接与PGN结合。
Toll-like receptor 2 (TLR2) has been recognized to mediate cell signaling in response to peptidoglycan (PGN), a major cell wall component of Gram-positive bacteria. The mechanism by which TLR2 recognizes PGN is unknown. It is not even clear whether TLR2 directly binds to PGN. In this study, we generated a soluble form of recombinant TLR2 (sTLR2) possessing only its putative extracellular domain by using the baculovirus expression system to examine the direct interaction between sTLR2 and PGN. sTLR2 bound avidly to insoluble PGN (iPGN) from Staphylococcus aureus coated onto microtiter wells in a concentration-dependent manner. In contrast, sTLR2 exhibited a very weak binding to lipopolysaccharide. iPGN cosedimented sTLR2 after the mixture of iPGN and sTLR2 had been incubated and centrifuged. sTLR2 partially attenuated the iPGN-induced NF-kappaB activation in TLR2-transfected HEK 293 cells and the iPGN-induced IL-8 secretion in U937 cells. One of anti-human TLR2 monoclonal antibodies, which blocked iPGN-induced NF-kappaB activation in TLR2-transfected cells, inhibited the binding of sTLR2 to iPGN. In addition, we found that sCD14 interacted with sTLR2 and increased the binding of sTLR2 to iPGN. From these results, we conclude that the extracellular TLR2 domain directly binds to PGN.