Center for Integrated Protein Science at Department Chemie, Technische Universität München Lichtenbergstrasse 4, 85747 Garching, Germany.
Helmholtz-Zentrum München (HMGU), Ingolstädter Landstr. 1, 85764 Neuherberg, Germany.
Sci Rep. 2017 Jan 27;7:41515. doi: 10.1038/srep41515.
Antibody light chain amyloidosis is a rare disease caused by fibril formation of secreted immunoglobulin light chains (LCs). The huge variety of antibody sequences puts a serious challenge to drug discovery. The green tea polyphenol epigallocatechin-3-gallate (EGCG) is known to interfere with fibril formation in general. Here we present solution- and solid-state NMR studies as well as MD simulations to characterise the interaction of EGCG with LC variable domains. We identified two distinct EGCG binding sites, both of which include a proline as an important recognition element. The binding sites were confirmed by site-directed mutagenesis and solid-state NMR analysis. The EGCG-induced protein complexes are unstructured. We propose a general mechanistic model for EGCG binding to a conserved site in LCs. We find that EGCG reacts selectively with amyloidogenic mutants. This makes this compound a promising lead structure, that can handle the immense sequence variability of antibody LCs.
抗体轻链淀粉样变性是一种由分泌免疫球蛋白轻链（LC）形成纤维而引起的罕见疾病。抗体序列的巨大多样性对药物发现构成了严重挑战。众所周知，绿茶多酚表没食子儿茶素没食子酸酯（EGCG）能普遍干扰纤维的形成。在这里，我们通过溶液和固态 NMR 研究以及 MD 模拟来描述 EGCG 与 LC 可变结构域的相互作用。我们确定了两个不同的 EGCG 结合位点，其中都包含一个脯氨酸作为重要的识别元件。通过定点突变和固态 NMR 分析证实了结合位点。EGCG 诱导的蛋白质复合物是无结构的。我们提出了一个 EGCG 与 LC 中保守位点结合的一般机制模型。我们发现 EGCG 选择性地与淀粉样变性突变体反应。这使得该化合物成为一种很有前途的先导结构，可以处理抗体 LC 中巨大的序列可变性。
