Folding and modulation of the helical conformation of Glycophorin A by point mutations
Folding and modulation of the helical conformation of Glycophorin A by point mutations
复制标题
点突变对血型糖蛋白 A 螺旋构象的折叠和调节
DOI：
10.1039/d3cp00263b
复制
发表时间：
2023
影响因子：
3.3
通讯作者：
Matysiak, Silvina
中科院分区：
文献类型：
--
作者：
Lee, Pei-Yin;Sahoo, Abhilash;Matysiak, Silvina
跨膜螺旋折叠和自结合在生物信号和跨生物膜运输途径中发挥着重要作用。通过分子模拟，探索这一过程的结构生物化学的研究一直局限于这一过程的单个片段--要么是螺旋形成，要么是二聚化。虽然在原子分辨率下，获取长时空尺度可能是令人望而却步的，但在粗粒度(CG)水平上，当前的方法要么使用额外的限制来防止自发展开，要么对侧链珠子的分辨率较低，限制了对突变引起的二聚体破坏的研究。为了弥补这些研究空白，在这项工作中，我们应用我们最近开发的CG模型(Prompt)来研究在十二烷基磷胆碱(DPC)胶束存在下，糖蛋白A(GPA)及其突变体的折叠和二聚化。我们的结果首次验证了折叠和二聚化是跨膜螺旋的独立事件的两阶段模型，并发现螺旋折叠和DPC-肽接触之间存在正相关。野生型(WT)GPA被观察到是具有特定GxxxG接触的右旋二聚体，这与实验结果一致。特定的点突变揭示了导致GPA结构稳定性的几个特征。虽然T87L突变体由于缺乏T87螺旋间氢键而形成反平行二聚体，但G79L突变体的螺旋性略有丧失，GxxxG区域出现了铰链状特征。我们注意到，受点突变影响，疏水环境中的局部变化有助于这种螺旋弯曲的发展。这项工作提供了胶束环境中GPA结构稳定性的整体概述，同时考虑了二级结构波动。此外，它为应用计算高效的CG模型来研究具有生理相关性的跨膜蛋白的构象变化提供了机会。
Transmembrane helix folding and self-association play important roles in biological signaling and transportation pathways across biomembranes. With molecular simulations, studies to explore the structural biochemistry of this process have been limited to focusing on individual fragments of this process – either helix formation or dimerization. While at an atomistic resolution, it can be prohibitive to access long spatio-temporal scales, at the coarse grained (CG) level, current methods either employ additional constraints to prevent spontaneous unfolding or have a low resolution on sidechain beads that restricts the study of dimer disruption caused by mutations. To address these research gaps, in this work, we apply our recent, in-house developed CG model (ProMPT) to study the folding and dimerization of Glycophorin A (GpA) and its mutants in the presence of Dodecyl-phosphocholine (DPC) micelles. Our results first validate the two-stage model that folding and dimerization are independent events for transmembrane helices and found a positive correlation between helix folding and DPC-peptide contacts. The wild type (WT) GpA is observed to be a right-handed dimer with specific GxxxG contacts, which agrees with experimental findings. Specific point mutations reveal several features responsible for the structural stability of GpA. While the T87L mutant forms anti-parallel dimers due to an absence of T87 interhelical hydrogen bonds, a slight loss in helicity and a hinge-like feature at the GxxxG region develops for the G79L mutant. We note that the local changes in the hydrophobic environment, affected by the point mutation, contribute to the development of this helical bend. This work presents a holistic overview of the structural stability of GpA in a micellar environment, while taking secondary structural fluctuations into account. Moreover, it presents opportunities for applications of computationally efficient CG models to study conformational alterations of transmembrane proteins that have physiological relevance.