State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, National Center for Magnetic Resonance at Wuhan, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, Hubei 430071, China.
Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China.
J Phys Chem B. 2022 Jul 7;126(26):4840-4848. doi: 10.1021/acs.jpcb.2c02713. Epub 2022 Jun 22.
The environmental condition is a critical regulation factor for protein behavior in solution. Several studies have shown that macromolecular crowders can modulate protein structures, interactions, and functions. Recent publications described the regulation of specific interaction by macromolecular crowders. However, the other category of protein-protein interaction, namely, the transient interaction, is rarely investigated, especially from the perspective of protein structure to study transient interactions between proteins. Here, we used nuclear magnetic resonance and small-angle X-ray/neutron scattering methods to structurally investigate the ensemble of the protein complex in dilute buffer and crowded environments. Histidine phosphocarrier protein (HPr) and the N-terminal domain of enzyme I (EIN) are the important components of the bacterial phosphotransfer system. Our results show that the addition of Ficoll-70 promotes HPr molecules to form the encounter complex with EIN maintained by long-range electrostatic interaction. However, when macromolecular crowder BSA is used, the soft interaction between BSA and HPr perturbs the active site of HPr, driving HPr to form an encounter complex with EIN at the weakly charged interface. Our results indicate that different macromolecular crowders could influence transient EIN-HPr interaction through different mechanisms and provide new insights into protein-protein interaction regulation in native environments.
环境条件是蛋白质在溶液中行为的关键调节因素。有几项研究表明，生物大分子拥挤剂可以调节蛋白质的结构、相互作用和功能。最近的出版物描述了生物大分子拥挤剂对特定相互作用的调节。然而，蛋白质-蛋白质相互作用的另一个类别，即瞬时相互作用，很少被研究，特别是从蛋白质结构的角度来研究蛋白质之间的瞬时相互作用。在这里，我们使用核磁共振和小角 X 射线/中子散射方法来结构研究稀缓冲液和拥挤环境中蛋白质复合物的集合。组氨酸磷酸载体蛋白（HPr）和酶 I 的 N 端结构域（EIN）是细菌磷酸转移系统的重要组成部分。我们的结果表明，添加 Ficoll-70 可促进 HPr 分子与由长程静电相互作用维持的 EIN 形成遭遇复合物。然而，当使用大分子拥挤剂 BSA 时，BSA 与 HPr 之间的软相互作用会干扰 HPr 的活性位点，促使 HPr 在带弱电荷的界面处与 EIN 形成遭遇复合物。我们的结果表明，不同的生物大分子拥挤剂可以通过不同的机制影响瞬时 EIN-HPr 相互作用，为在天然环境中调节蛋白质-蛋白质相互作用提供了新的见解。
