Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland, USA.
Section on Molecular Transport, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA.
Proteomics. 2022 Mar;22(5-6):e2100060. doi: 10.1002/pmic.202100060. Epub 2021 Dec 6.
Voltage-activated complexation is the process by which a transmembrane potential drives complex formation between a membrane-embedded channel and a soluble or membrane-peripheral target protein. Metabolite and calcium flux across the mitochondrial outer membrane was shown to be regulated by voltage-activated complexation of the voltage-dependent anion channel (VDAC) and either dimeric tubulin or α-synuclein (αSyn). However, the roles played by VDAC's characteristic attributes-its anion selectivity and voltage gating behavior-have remained unclear. Here, we compare in vitro measurements of voltage-activated complexation of αSyn with three well-characterized β-barrel channels-VDAC, MspA, and α-hemolysin-that differ widely in their organism of origin, structure, geometry, charge density distribution, and voltage gating behavior. The voltage dependences of the complexation dynamics for the different channels are observed to differ quantitatively but have similar qualitative features. In each case, energy landscape modeling describes the complexation dynamics in a manner consistent with the known properties of the individual channels, while voltage gating does not appear to play a role. The reaction free energy landscapes thus calculated reveal a non-trivial dependence of the αSyn/channel complex stability on the surface density of αSyn.
电压激活复合物形成是一种过程，在此过程中跨膜电位驱动膜嵌入式通道和可溶性或膜外周靶蛋白之间形成复合物。已经表明，代谢物和钙跨线粒体外膜的流动受到电压依赖性阴离子通道 (VDAC) 与二聚体微管蛋白或α-突触核蛋白 (αSyn) 之间的电压激活复合物形成的调节。然而，VDAC 的特征属性——阴离子选择性和电压门控行为——所起的作用仍然不清楚。在这里，我们比较了αSyn 与三种经过充分表征的β-桶通道（VDAC、MspA 和 α-溶血素）的体外电压激活复合物形成的测量结果，这些通道在起源、结构、几何形状、电荷密度分布和电压门控行为方面差异很大。观察到不同通道的复合物形成动力学的电压依赖性在数量上有所不同，但具有相似的定性特征。在每种情况下，能量景观模型以与各个通道的已知特性一致的方式描述复合物形成动力学，而电压门控似乎不起作用。因此计算出的反应自由能景观揭示了 αSyn/通道复合物稳定性对 αSyn 表面密度的非平凡依赖性。
