Structural similarity between the hydrophobic fluorescent probe and lipid A as a ligand of MD-2
Structural similarity between the hydrophobic fluorescent probe and lipid A as a ligand of MD-2
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DOI：
10.1096/fj.06-5862com
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发表时间：
2006-09-01
期刊：
影响因子：
4.8
通讯作者：
Jerala, Roman
中科院分区：
文献类型：
--
作者：
Mancek-Keber, Mateja;Jerala, Roman
Toll样受体（TLR）属于模式识别受体家族，因为它们识别共享广泛结构模式而不是单一定义结构的分子。细菌LPS被MD-2识别，MD-2与TLR 4的细胞外结构域相关。了解MD-2的分子识别模式可能会导致有效的抑制剂的过度LPS信号所需的早期治疗脓毒症。脂质A的酰基链可变性对其生物活性的影响表明，除了静电相互作用，识别还必须涉及疏水相互作用。我们表明，荧光疏水探针双ANS结合MD-2的解离常数在10纳摩尔范围内，糖基化和非糖基化的MD-2，并需要其天然构象。bis-ANS的结合位点与LPS的结合位点重叠，并且在单个色氨酸残基附近。此外，通过UV光的bis-ANS的光掺入抑制MD-2赋予LPS对TLR 4转染的HEK 293细胞系的响应性的能力。我们的研究结果表明，由MD-2识别的结构模式是由疏水补丁和一对分离的负电荷定义的。Mancek-Keber，M.，杰拉拉河疏水性荧光探针与作为MD-2配体的脂质A之间的结构相似性。
Toll-like receptors (TLRs) belong to the family of pattern recognition receptors, as they recognize molecules sharing a broad structural pattern rather than a single defined structure. Bacterial LPS is recognized by MD-2, which is associated with the extracellular domain of TLR4. Understanding the molecular recognition pattern of MD-2 could lead to efficient inhibitors of the excessive LPS signaling needed for early treatment of sepsis. The effect of the acyl chain variability of lipid A on its biological activity indicates that in addition to electrostatic interactions, the recognition must also involve hydrophobic interactions. We show that the fluorescent hydrophobic probe bis-ANS binds to MD-2 with a dissociation constant in the 10 nanomolar range, both to glycosylated and to nonglycosylated MD-2, and requires its native conformation. The binding site of bis-ANS overlaps with the binding site of LPS and is in the proximity of the single tryptophan residue. Furthermore, photoincorporation of bis-ANS by UV light inhibits the ability of MD-2 to confer the LPS responsiveness to the TLR4-transfected HEK293 cell line. Our results show that the structural pattern recognized by MD-2 is defined by the hydrophobic patch and a pair of separated negative charges. Mancek-Keber, M., Jerala, R. Structural similarity between the hydrophobic fluorescent probe and lipid A as a ligand of MD-2.