Department of Chemistry, The University of Texas at Austin, Austin, Texas.
Department of Neuroscience, The University of Texas at Austin, Austin, Texas.
Biophys J. 2024 Jul 16;123(14):2001-2011. doi: 10.1016/j.bpj.2023.12.019. Epub 2023 Dec 23.
Cell signaling is an important process involving complex interactions between lipids and proteins. The myristoylated alanine-rich C-kinase substrate (MARCKS) has been established as a key signaling regulator, serving a range of biological roles. Its effector domain (ED), which anchors the protein to the plasma membrane, induces domain formation in membranes containing phosphatidylinositol 4,5-bisphosphate (PIP) and phosphatidylserine (PS). The mechanisms governing the MARCKS-ED binding to membranes remain elusive. Here, we investigate the composition-dependent affinity and MARCKS-ED-binding-induced changes in interfacial environments using two-dimensional infrared spectroscopy and fluorescence anisotropy. Both negatively charged lipids facilitate the MARCKS-ED binding to lipid vesicles. Although the hydrogen-bonding structure at the lipid-water interface remains comparable across vesicles with varied lipid compositions, the dynamics of interfacial water show divergent patterns due to specific interactions between lipids and peptides. Our findings also reveal that PIP becomes sequestered by bound peptides, while the distribution of PS exhibits no discernible change upon peptide binding. Interestingly, PIP and PS become colocalized into domains both in the presence and absence of MARCKS-ED. More broadly, this work offers molecular insights into the effects of membrane composition on binding.
细胞信号转导是一个涉及脂质和蛋白质之间复杂相互作用的重要过程。肉豆蔻酰化丙氨酸丰富的 C 激酶底物（MARCKS）已被确定为关键的信号调节因子，具有多种生物学功能。其效应结构域（ED）将蛋白质锚定在质膜上，诱导含有磷脂酰肌醇 4,5-二磷酸（PIP）和磷脂酰丝氨酸（PS）的膜形成结构域。控制 MARCKS-ED 与膜结合的机制仍不清楚。在这里，我们使用二维红外光谱和荧光各向异性研究了组成依赖性亲和力以及 MARCKS-ED 结合诱导的界面环境变化。两种带负电荷的脂质都促进 MARCKS-ED 与脂质体的结合。尽管脂质-水界面的氢键结构在具有不同脂质组成的脂质体之间保持相似，但由于脂质和肽之间的特定相互作用，界面水的动力学表现出不同的模式。我们的研究结果还表明，结合肽会将 PIP 隔离，而结合肽后 PS 的分布没有明显变化。有趣的是，无论是否存在 MARCKS-ED，PIP 和 PS 都会聚集到域中。更广泛地说，这项工作提供了对膜组成对结合影响的分子见解。
