Solution NMR characterization of chemokine CXCL8/IL-8 monomer and dimer binding to glycosaminoglycans: structural plasticity mediates differential binding interactions.
Solution NMR characterization of chemokine CXCL8/IL-8 monomer and dimer binding to glycosaminoglycans: structural plasticity mediates differential binding interactions.
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DOI：
10.1042/bj20150059
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发表时间：
2015-11-15
期刊：
影响因子：
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通讯作者：
Rajarathnam K
中科院分区：
文献类型：
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作者：
Joseph PR;Mosier PD;Desai UR;Rajarathnam K
结构可塑性在决定CXCL8单体和二聚体与糖胺聚糖（GAGs）的差异结合中起主要作用，该二聚体是高亲和力的GAG配体。我们认为这些特性在协调体内趋化因子介导的中性粒细胞功能中发挥重要作用。趋化因子CXCL8/白细胞介素-8 （IL-8）在指导中性粒细胞和少突胶质细胞对抗感染/损伤和肿瘤细胞转移发展中起关键作用。CXCL8以单体和二聚体形式存在，两种形式与糖胺聚糖（GAGs）相互作用介导这些不同的细胞过程。然而，关于CXCL8-GAG相互作用的结构基础知之甚少。关于亲和性，几何形状以及单体或二聚体是否是高亲和性GAG配体，有相互矛盾的报道。为了解决这些问题，我们利用溶液核磁共振光谱表征了一系列肝素衍生的低聚糖[肝素双糖（dp2），肝素四糖（dp4），肝素八糖（dp8）和肝素14-聚体（dp14）]与野生型（WT）二聚体和设计单体的结合。二聚体和单体之间以及长糖和短糖之间的结合诱导的化学位移微扰（CSP）的模式和程度不同。基于核磁共振的结构模型表明，不同的相互作用模式共存，相互作用的性质因单体和二聚体以及低聚糖的长度而异。MD模拟表明，结合界面具有结构塑性，并提供了结合界面动态特性的特定细节。在WT CXCL8作为单体和二聚体存在的条件下进行的结合研究提供了明确的证据，表明二聚体是高亲和力的GAG配体。总之，我们的数据表明，一组核心残基作为主要的识别/结合位点，一组外围残基定义了各种结合几何形状，并且结合界面的结构可塑性允许多种结合相互作用。我们得出结论，结构可塑性最有可能调节体内CXCL8单体/二聚体- gag的相互作用和功能。
Structural plasticity plays a major role in determining differential binding of CXCL8 monomer and dimer to glycosaminoglycans (GAGs) and that dimer is the high-affinity GAG ligand. We propose that these properties play important roles in orchestrating in vivo chemokine-mediated neutrophil function. Chemokine CXCL8/interleukin-8 (IL-8) plays a crucial role in directing neutrophils and oligodendrocytes to combat infection/injury and tumour cells in metastasis development. CXCL8 exists as monomers and dimers and interaction of both forms with glycosaminoglycans (GAGs) mediate these diverse cellular processes. However, very little is known regarding the structural basis underlying CXCL8–GAG interactions. There are conflicting reports on the affinities, geometry and whether the monomer or dimer is the high-affinity GAG ligand. To resolve these issues, we characterized the binding of a series of heparin-derived oligosaccharides [heparin disaccharide (dp2), heparin tetrasaccharide (dp4), heparin octasaccharide (dp8) and heparin 14-mer (dp14)] to the wild-type (WT) dimer and a designed monomer using solution NMR spectroscopy. The pattern and extent of binding-induced chemical shift perturbation (CSP) varied between dimer and monomer and between longer and shorter oligosaccharides. NMR-based structural models show that different interaction modes coexist and that the nature of interactions varied between monomer and dimer and oligosaccharide length. MD simulations indicate that the binding interface is structurally plastic and provided residue-specific details of the dynamic nature of the binding interface. Binding studies carried out under conditions at which WT CXCL8 exists as monomers and dimers provide unambiguous evidence that the dimer is the high-affinity GAG ligand. Together, our data indicate that a set of core residues function as the major recognition/binding site, a set of peripheral residues define the various binding geometries and that the structural plasticity of the binding interface allows multiplicity of binding interactions. We conclude that structural plasticity most probably regulates in vivo CXCL8 monomer/dimer–GAG interactions and function.