Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, United States.
Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, United States.
Biochim Biophys Acta Biomembr. 2021 Oct 1;1863(10):183660. doi: 10.1016/j.bbamem.2021.183660. Epub 2021 Jun 4.
Endophilin is an N-BAR protein, which is characterized by a crescent-shaped BAR domain and an amphipathic helix that contributes to the membrane binding of these proteins. The exact function of that H0 helix has been a topic of debate. In mammals, there are five different endophilin isoforms, grouped into A (three members) and B (two members) subclasses, which have been described to differ in their subcellular localization and function. We asked to what extent molecular properties of the H0 helices of these members affect their membrane targeting behavior. We found that all H0 helices of the endophilin isoforms display a two-state equilibrium between disordered and α-helical states in which the helical secondary structure can be stabilized through trifluoroethanol. The helicities in high TFE were strikingly different among the H0 peptides. We investigated H0-membrane partitioning by the monitoring of secondary structure changes via CD spectroscopy. We found that the presence of anionic phospholipids is critical for all H0 helices partitioning into membranes. Membrane partitioning is found to be sensitive to variations in membrane complexity. Overall, the H0 B subfamily displays stronger membrane partitioning than the H0 A subfamily. The H0 A peptide-membrane binding occurs predominantly through electrostatic interactions. Variation among the H0 A subfamily may be attributed to slight alterations in the amino acid sequence. Meanwhile, the H0 B subfamily displays greater specificity for certain membrane compositions, and this may link H0 B peptide binding to endophilin B's cellular function.
内收蛋白是一种 N-BAR 蛋白,其特征是具有新月形 BAR 结构域和一个两亲性螺旋,有助于这些蛋白质与膜结合。该 H0 螺旋的确切功能一直存在争议。在哺乳动物中,有五种不同的内收蛋白同工型,分为 A(三个成员)和 B(两个成员)亚类,其亚细胞定位和功能有所不同。我们想知道这些成员的 H0 螺旋的分子特性在多大程度上影响它们的膜靶向行为。我们发现,所有内收蛋白同工型的 H0 螺旋都在无序和α-螺旋之间存在两态平衡,其中螺旋二级结构可以通过三氟乙醇稳定。在高 TFE 下,H0 肽的螺旋性差异非常明显。我们通过监测二级结构变化的 CD 光谱研究了 H0-膜分配。我们发现阴离子磷脂的存在对于所有 H0 螺旋进入膜都是至关重要的。膜分配对膜复杂性的变化敏感。总体而言,H0 B 亚家族比 H0 A 亚家族表现出更强的膜分配能力。H0 A 肽与膜的结合主要通过静电相互作用。H0 A 亚家族的变异可能归因于氨基酸序列的微小改变。同时,H0 B 亚家族对特定的膜成分表现出更大的特异性,这可能将 H0 B 肽与内收蛋白 B 的细胞功能联系起来。