Single-chain insulin analogs threaded by the insulin receptor αCT domain.
Single-chain insulin analogs threaded by the insulin receptor αCT domain.
复制标题
单链胰岛素类似物由胰岛素受体αCT结构域连接。
DOI：
10.1016/j.bpj.2022.09.038
复制
发表时间：
2022
影响因子：
3.4
通讯作者：
Smith,BrianJ
中科院分区：
文献类型：
--
作者：
Smith,NicholasA;Menting,JohnG;Weiss,MichaelA;Lawrence,MichaelC;Smith,BrianJ
胰岛素是治疗糖尿病的主要药物，但其热稳定性使全球运输和储存复杂化。冷链运输，加上优化的配方和材料，在一定程度上防止淀粉样蛋白的成核，从而使激素活性失活。因此，这些问题促使设计具有增加的稳定性的类似物，其中有希望的方法是单链胰岛素（SCI），其C结构域（相对于胰岛素原缩短）类似于单链生长因子（IGF）的那些。我们以前已经证明，优化的SCI可以表现出天然样的激素活性，具有增强的热稳定性和显着的抗纤颤性。在此，我们描述了与胰岛素受体（IR）胞外域模块（N端α亚基结构域L1-CR和C端αCT肽;“微受体”[μIR]）结合的超稳定SCI（C结构域长度6;序列EEGPRR）的晶体结构。SCI-μIR复合物的结构由Fv模块稳定，使用分辨率为2.6 nm的衍射数据确定。值得注意的是，αCT肽（IR-A同种型）“穿过”柔性C结构域和胰岛素核心之间的间隙。为了探索这种螺纹，我们进行了分子动力学模拟，以1）比较螺纹与非螺纹结合模式和2）评估C结构域长度对这些交替模式的影响。模拟（采用传统和增强的采样模拟）提供的证据表明，非常短的连接体（C-结构域长度为-1）将限制SCI中的缺口开放，从而损害穿线。我们设想，类似的线程发生在完整的SCI-IR复杂的合理化为什么最小的C-结构域长度块完整的活动，并可能被利用来设计新的受体亚型特异性类似物。
Insulin is a mainstay of therapy for diabetes mellitus, yet its thermal stability complicates global transportation and storage. Cold-chain transport, coupled with optimized formulation and materials, prevents to some degree nucleation of amyloid and hence inactivation of hormonal activity. These issues hence motivate the design of analogs with increased stability, with a promising approach being single-chain insulins (SCIs), whose C domains (foreshortened relative to proinsulin) resemble those of the single-chain growth factors (IGFs). We have previously demonstrated that optimized SCIs can exhibit native-like hormonal activity with enhanced thermal stability and marked resistance to fibrillation. Here, we describe the crystal structure of an ultrastable SCI (C-domain length 6; sequence EEGPRR) bound to modules of the insulin receptor (IR) ectodomain (N-terminalα-subunit domains L1-CR and C-terminalαCT peptide; "microreceptor" [μIR]). The structure of the SCI-μIR complex, stabilized by an Fv module, was determined using diffraction data to a resolution of 2.6 Å. Remarkably, theαCT peptide (IR-A isoform) "threads" through a gap between the flexible C domain and the insulin core. To explore such threading, we undertook molecular dynamics simulations to 1) compare threaded with unthreaded binding modes and 2) evaluate effects of C-domain length on these alternate modes. The simulations (employing both conventional and enhanced sampling simulations) provide evidence that very short linkers (C-domain length of −1) would limit gap opening in the SCI and so impair threading. We envisage that analogous threading occurs in the intact SCI-IR complex—rationalizing why minimal C-domain lengths block complete activity—and might be exploited to design novel receptor-isoform-specific analogs.