Hu Youli, Sun Zhe, Eaton Julian T, Bouloux Pierre M G, Perkins Stephen J
Centre of Neuroendocrinology, Department of Medicine, Royal Free and University College School of Medicine, Rowland Hill Street, London NW3 2PF, UK.
J Mol Biol. 2005 Jul 15;350(3):553-70. doi: 10.1016/j.jmb.2005.04.031.
Kallmann's syndrome corresponds to a loss of sense of smell and hypogonadotrophic hypogonadism. Defects in anosmin-1 result in the X-linked inherited form of Kallmann's syndrome. Anosmin-1 is an extracellular matrix protein comprised of an N-terminal, cysteine-rich (Cys-box) domain and a whey acidic protein-like (WAP) domain, followed by four fibronectin type III (FnIII) domains. The solution structures of recombinant proteins containing the first three domains (PIWF1) and all six domains (PIWF4) were determined by X-ray scattering and analytical ultracentrifugation. Guinier analyses showed that PIWF1 and PIWF4 have different radii of gyration (R(G)) values of 3.1 nm and 6.7 nm, respectively, but similar cross-sectional radii of gyration (R(XS)) values of 1.5 nm and 1.9 nm, respectively. Distance distribution functions showed that the maximum lengths of PIWF1 and PIWF4 were 11 nm and 23 nm, respectively. Analytical ultracentrifugation gave sedimentation coefficients of 2.52 S and 3.55 S for PIWF1 and PIWF4, respectively. The interpretation of the scattering data by constrained modelling requires homology models for all six domains in anosmin-1. While models were already available for the WAP and FnIII domains, searches suggested the Cys-box domain may resemble the cysteine-rich region of the insulin-like growth factor receptor. Automated constrained molecular modelling based on joining the anosmin-1 domains with structurally randomised linkers resulted in 10,000 models for anosmin-1. A trial-and-error search showed that about 0.1-1.4% of these models fitted the X-ray data. The best models showed that the three domains and six domains in PIWF1 and PIWF4, respectively, were extended. The inter-domain linkers in anosmin-1 could not all be extended at the same time, and there was evidence for inter-domain flexibility. Models with folded-back domain arrangements do not fit the data. These solution structures account for the known biological function of anosmin-1, in particular its ability to interact with its three macromolecular ligands.
卡尔曼综合征表现为嗅觉丧失和低促性腺激素性性腺功能减退。anosmin - 1缺陷导致X连锁遗传型卡尔曼综合征。Anosmin - 1是一种细胞外基质蛋白，由一个N端富含半胱氨酸（Cys盒）结构域、一个乳清酸性蛋白样（WAP）结构域，随后是四个III型纤连蛋白（FnIII）结构域组成。通过X射线散射和分析超速离心确定了包含前三个结构域（PIWF1）和所有六个结构域（PIWF4）的重组蛋白的溶液结构。吉尼尔分析表明，PIWF1和PIWF4的回转半径（R(G)）值分别为3.1 nm和6.7 nm，但横截面回转半径（R(XS)）值相似，分别为1.5 nm和1.9 nm。距离分布函数表明，PIWF1和PIWF4的最大长度分别为11 nm和23 nm。分析超速离心得出PIWF1和PIWF4的沉降系数分别为2.52 S和3.55 S。通过约束建模对散射数据进行解释需要anosmin - 1所有六个结构域的同源模型。虽然WAP和FnIII结构域已有模型，但搜索表明Cys盒结构域可能类似于胰岛素样生长因子受体的富含半胱氨酸区域。基于将anosmin - 1结构域与结构随机化的接头连接的自动约束分子建模产生了10,000个anosmin - 1模型。反复试验搜索表明，这些模型中约0.1 - 1.4%符合X射线数据。最佳模型表明，PIWF1和PIWF4中的三个结构域和六个结构域分别是伸展的。Anosmin - 1中的结构域间接头不能同时全部伸展，并且有证据表明存在结构域间的灵活性。结构域排列折叠的模型不符合数据。这些溶液结构解释了anosmin - 1已知的生物学功能，特别是其与三种大分子配体相互作用的能力。
