Document Type
Article
Publication Date
6-22-2025
Abstract
Plexin-semaphorin signaling regulates key processes such as cell migration, neuronal development, angiogenesis, and immune responses. Plexins stand out because they can directly bind with both Rho- and Ras-family small GTPases through their intracellular domains when these GTPases are in their active, GTP-bound states. This binding occurs via intracellular regions, which include a Rho-GTPase binding domain and a GTPase-activating protein (GAP) segment. Studies have shown that Rho and Ras GTPases play vital roles in plexin signaling and activation. However, the structural dynamics of plexins and GTPases and how these conformational changes affect interactions when plexin is bound with both Ras and Rho-GTPases or bound to only one specific GTPase have remained unclear. In this study, we conducted molecular dynamics simulations on six distinct plexin-GTPase bound systems to investigate the differences in conformations and dynamics between plexin-B1 and three GTPases: Rap1b, Rnd1, and Rac1. Our analysis revealed that dynamics with Rac1 are more altered compared to Rnd1, depending on whether plexin's GAP domain is bound or unbound to Rap1b. In addition, we further investigated alterations in network centralities and compared the network dynamics of the plexin-GTPase complexes, focusing on the differences when plexin is bound to both Ras (Rap1b) and Rho-GTPases (Rnd1/Rac1) versus when it is bound to only one GTPase. Our study revealed that Rnd1 exhibits stronger and more stable interactions with plexin-B1 in the absence of Rap1b, while Rac1 shows fewer and less stable connections in comparison. These computational models have features that broadly agree with experimental results from hydrogen-deuterium exchange detected by mass spectrometry. Such insights provide a better understanding of the molecular mechanisms underlying plexin-GTPase interactions and the complexities of signaling mechanisms involving GTPases in general.
Keywords
dynamic allostery, gtpases, hydrogen-deuterium exchange, molecular dynamics simulations, plexin transmembrane receptor, protein-protein interactions
Language
English
Publication Title
Protein Science
Grant
R01AG089561
Rights
© 2025 The Author(s). This is an Open Access work distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Recommended Citation
Bhattarai N, Morrison L, Gomes AF, Savage P, Sahoo AR, Buck M. Computational model predicts function of Rho-GTPase binding for plexin receptor GAP activity on Rap1b via dynamic allosteric changes. Protein Science. 2025; 34(7):e70196. https://doi.org/10.1002/pro.70196
Manuscript Version
Final Publisher Version