Kannan Adithi, Chaurasiya Dhruv Kumar, Naganathan Athi N
Department of Biotechnology, Bhupat & Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India.
ACS Bio Med Chem Au. 2023 Nov 7;4(1):53-67. doi: 10.1021/acsbiomedchemau.3c00047. eCollection 2024 Feb 21.
The extent and molecular basis of interdomain communication in multidomain proteins, central to understanding allostery and function, is an open question. One simple evolutionary strategy could involve the selection of either conflicting or favorable electrostatic interactions across the interface of two closely spaced domains to tune the magnitude of interdomain connectivity. Here, we study a bilobed domain FF34 from the eukaryotic p190A RhoGAP protein to explore one such design principle that mediates interdomain communication. We find that while the individual structural units in wild-type FF34 are marginally coupled, they exhibit distinct intrinsic stabilities and low cooperativity, manifesting as slow folding. The FF3-FF4 interface harbors a frustrated network of highly conserved electrostatic interactions-a charge -that promotes the population of multiple, decoupled, and non-native structural modes on a rugged native landscape. Perturbing this network via a charge-reversal mutation not only enhances stability and cooperativity but also dampens the fluctuations globally and speeds up the folding rate by at least an order of magnitude. Our work highlights how a conserved but nonoptimal network of interfacial electrostatic interactions shapes the native ensemble of a bilobed protein, a feature that could be exploited in designing molecular systems with long-range connectivity and enhanced cooperativity.
多结构域蛋白质中结构域间通讯的程度和分子基础是一个尚未解决的问题，这对于理解变构和功能至关重要。一种简单的进化策略可能涉及在两个紧密相邻的结构域界面处选择相互冲突或有利的静电相互作用，以调节结构域间连接的强度。在这里，我们研究了真核生物p190A RhoGAP蛋白中的双叶结构域FF34，以探索一种介导结构域间通讯的设计原则。我们发现，虽然野生型FF34中的各个结构单元仅有微弱的耦合，但它们表现出不同的固有稳定性和低协同性，表现为折叠缓慢。FF3-FF4界面存在一个由高度保守的静电相互作用构成的受挫网络——一种电荷——它在崎岖的天然构象景观上促进了多种解耦的非天然结构模式的出现。通过电荷反转突变扰动这个网络不仅增强了稳定性和协同性，还全局抑制了波动，并将折叠速率提高了至少一个数量级。我们的工作突出了界面静电相互作用的保守但非最优网络如何塑造双叶蛋白的天然构象集合，这一特征可用于设计具有长程连接性和增强协同性的分子系统。
