Iserentant Hannes, Peelman Frank, Defeau Delphine, Vandekerckhove Joël, Zabeau Lennart, Tavernier Jan
Flanders Interuniversity Institute for Biotechnology, Department of Medical Protein Research (VIB09), Ghent University, Faculty of Medicine and Health Sciences, Baertsoenkaai 3, 9000 Ghent, Belgium.
J Cell Sci. 2005 Jun 1;118(Pt 11):2519-27. doi: 10.1242/jcs.02386.
Despite the impact of the leptin system on body weight and other physiologic processes, little is known about the binding of leptin to its receptor. The extracellular domain of the leptin receptor consists of two cytokine receptor homology (CRH) domains separated by an immunoglobulin-like domain, and followed by two juxtamembrane fibronectin type III modules. The CRH2 domain functions as a high-affinity binding site for leptin, and we previously demonstrated interaction with helices A and C of leptin. In this work, we constructed a homology model for the leptin/CRH2 complex and performed a detailed mutation analysis of the CRH2/leptin interface. Using both cell-based and in vitro binding assays using the isolated CRH2 domain, we show the critical role of hydrophobic interactions between Leu 13 and Leu 86 of leptin and Leu 504 in CRH2 in leptin binding and signalling. This binding pattern closely resembles the interaction of other four-helix bundle long chain cytokines with the CRH domain of their cognate receptors.
尽管瘦素系统对体重及其他生理过程有影响，但关于瘦素与其受体的结合却知之甚少。瘦素受体的细胞外结构域由两个细胞因子受体同源（CRH）结构域组成，中间隔着一个免疫球蛋白样结构域，后面接着两个近膜纤连蛋白III型模块。CRH2结构域作为瘦素的高亲和力结合位点，我们之前已证明其与瘦素的A螺旋和C螺旋相互作用。在这项研究中，我们构建了瘦素/CRH2复合物的同源模型，并对CRH2/瘦素界面进行了详细的突变分析。使用基于细胞的实验以及利用分离出的CRH2结构域进行体外结合实验，我们证明了瘦素的Leu 13和Leu 86与CRH2中的Leu 504之间的疏水相互作用在瘦素结合和信号传导中的关键作用。这种结合模式与其他四螺旋束长链细胞因子与其同源受体的CRH结构域的相互作用非常相似。
