A dominant conformational role for amino acid diversity in minimalist protein-protein interfaces
A dominant conformational role for amino acid diversity in minimalist protein-protein interfaces
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DOI：
10.1016/j.jmb.2008.06.014
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发表时间：
2008-08-29
影响因子：
5.6
通讯作者：
Koide, Shohei
中科院分区：
文献类型：
--
作者：
Gilbreth, Ryan N.;Esaki, Kaori;Koide, Shohei
最近的研究表明，高度简化的相互作用表面组成的两个氨基酸，酪氨酸和丝氨酸的组合，表现出高亲和力和特异性。因此，这种极简界面的高功能水平可能表明在天然界面中看到的更大的氨基酸多样性的小贡献。为了解决这个问题，我们已经产生了一对建立在纤连蛋白III型支架上的结合蛋白，称为“单体”。“一个单体含有Tyr/Ser二进制代码界面（称为YS），另一个含有扩展的氨基酸多样性界面（YSX），但两者都结合到相同的目标，麦芽糖结合蛋白。与YS单体相比，YSX单体以更高的亲和力、更慢的解离速率和更有利的疏水贡献结合。高分辨率的X射线晶体结构显示，这两种蛋白质结合到一个基本相同的表位，提供了一个独特的机会，直接研究氨基酸多样性在蛋白质相互作用界面的作用。令人惊讶的是，Tyr仍然在YSX互补位中占主导地位，并且另外的氨基酸类型主要用于构象优化由酪氨酸形成的接触。扫描突变表明，虽然所有接触的Tyr侧链在YS单体中都是必需的，但YSX界面对突变更耐受。这些结果表明，构象，而不是化学，其他类型的氨基酸的多样性提供了更高的功能和进化的鲁棒性，支持的主导作用的酪氨酸和构象多样性的重要性，在形成蛋白质相互作用界面。(c)2008爱思唯尔有限公司保留所有权利。
Recent studies have shown that highly simplified interaction surfaces consisting of combinations of just two amino acids, Tyr and Ser, exhibit high affinity and specificity. The high functional levels of such minimalist interfaces might thus indicate small contributions of greater amino acid diversity seen in natural interfaces. Toward addressing this issue, we have produced a pair of binding proteins built on the fibronectin type III scaffold, termed "monobodies." One monobody contains the Tyr/Ser binary-code interface (termed YS) and the other contains an expanded amino acid diversity interface (YSX), but both bind to an identical target, maltose-binding protein. The YSX monobody bound with higher affinity, a slower off rate and a more favorable enthalpic contribution than the YS monobody. High-resolution X-ray crystal structures revealed that both proteins bound to an essentially identical epitope, providing a unique opportunity to directly investigate the role of amino acid diversity in a protein interaction interface. Surprisingly, Tyr still dominates the YSX paratope and the additional amino acid types are primarily used to conformationally optimize contacts made by tyrosines. Scanning mutagenesis showed that while all contacting Tyr side chains are essential in the YS monobody, the YSX interface was more tolerant to mutations. These results suggest that the conformational, not chemical, diversity of additional types of amino acids provided higher functionality and evolutionary robustness, supporting the dominant role of Tyr and the importance of conformational diversity in forming protein interaction interfaces. (c) 2008 Elsevier Ltd. All rights reserved.