Transient Electrostatic Interactions between Fcp1 and Rap74 Bias the Conformational Ensemble of the Complex with Minimal Impact on Binding Affinity
Transient Electrostatic Interactions between Fcp1 and Rap74 Bias the Conformational Ensemble of the Complex with Minimal Impact on Binding Affinity
复制标题
Fcp1 和 Rap74 之间的瞬态静电相互作用使复合物的构象整体产生偏差，对结合亲和力的影响最小
DOI：
10.1021/acs.jpcb.1c05131
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Showalter, Scott A.
中科院分区：
文献类型：
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作者：
Prieto, Victor A.;Namitz, Kevin E.;Showalter, Scott A.
内含子无序蛋白（IDP）序列通常含有高比例的带电残基，以及它们的高度亲水性和溶剂化。对于高净电荷IDP，长程静电相互作用被认为在调节蛋白质-蛋白质相互作用的强度或动力学中起作用。在这项工作中，我们研究了由模型IDP的带电区域介导的分子内相互作用，磷酸酶Fcp 1的C-末端尾部。具体而言，这项工作的重点是酸性和碱性补丁的Fcp 1的一级结构和它们的贡献结合其主要的碱性合作伙伴，Rap 74的翼螺旋结构域之间的分子间相互作用。我们观察到分子内和分子间的相互作用，通过顺磁弛豫增强（PRE）与带相反电荷的区域相互关联，无论是在未结合的Fcp 1和Fcp 1-Rap 74复合物。这种复合物的形成是由最小结合基序中的疏水相互作用强烈驱动的。在这里，我们测试的假设，在Fcp 1的侧翼结合螺旋的带电残基也有助于结合的强度。Fcp 1中的电荷反转突变通常支持这一假设，而PRE数据表明在未结合的集合中观察到的瞬时相互作用被替换为在复合物中与Rap 74的类似瞬时相互作用。
Intrinsically disordered protein (IDP) sequences often contain a high proportion of charged residues in conjunction with their high degree of hydrophilicity and solvation. For high net charge IDPs, long-range electrostatic interactions are thought to play a role in modulating the strength or kinetics of protein–protein interactions. In this work, we examined intramolecular interactions mediated by charged regions of a model IDP, the C-terminal tail of the phosphatase Fcp1. Specifically, this work focuses on intermolecular interactions between acidic and basic patches in the primary structure of Fcp1 and their contributions to binding its predominantly basic partner, the winged helix domain of Rap74. We observe both intramolecular and intermolecular interactions through paramagnetic relaxation enhancement (PRE) consistent with oppositely charged regions associating with one another, both in unbound Fcp1 and in the Fcp1–Rap74 complex. Formation of this complex is strongly driven by hydrophobic interactions in the minimal binding motif. Here, we test the hypothesis that charged residues in Fcp1 that flank the binding helix also contribute to the strength of binding. Charge inversion mutations in Fcp1 generally support this hypothesis, while PRE data suggest substitution of observed transient interactions in the unbound ensemble for similarly transient interactions with Rap74 in the complex.