Rebaud Samuel, Simon Anne, Wang Conan K, Mason Lyndel, Blum Loïc, Hofmann Andreas, Girard-Egrot Agnès
Institut de Chimie et Biochimie Moléculaires et Supramoléculaires, Université Lyon 1, University of Lyon, ICBMS, CNRS UMR 5246, Bât. Curien, 43 bd du 11 Nov. 1918, F-69622 Villeurbanne cedex, France.
Structural Chemistry Program, Eskitis Institute, Griffith University, Brisbane, Queensland, Australia.
PLoS One. 2014 Apr 3;9(4):e93948. doi: 10.1371/journal.pone.0093948. eCollection 2014.
The neuronal calcium sensor proteins Visinin-like Proteins 1 (VILIP-1) and 3 (VILIP-3) are effectors of guanylyl cyclase and acetyl choline receptors, and transduce calcium signals in the brain. The "calcium-myristoyl" switch, which involves a post-translationally added myristoyl moiety and calcium binding, is thought to regulate their membrane binding capacity and therefore, play a critical role in their mechanism of action. In the present study, we investigated the effect of membrane composition and solvent conditions on the membrane binding mechanisms of both VILIPs using lipid monolayers at the air/buffer interface. Results based on comparison of the adsorption kinetics of the myristoylated and non-myristoylated proteins confirm the pivotal role of calcium and the exposed myristol moiety for sustaining the membrane-bound state of both VILIPs. However, we also observed binding of both VILIP proteins in the absence of calcium and/or myristoyl conjugation. We propose a two-stage membrane binding mechanism for VILIP-1 and VILIP-3 whereby the proteins are initially attracted to the membrane surface by electrostatic interactions and possibly by specific interactions with highly negatively charged lipids head groups. The extrusion of the conjugated myristoyl group, and the subsequent anchoring in the membrane constitutes the second stage of the binding mechanism, and ensures the sustained membrane-bound form of these proteins.
神经元钙传感器蛋白类视锥蛋白样蛋白1（VILIP-1）和3（VILIP-3）是鸟苷酸环化酶和乙酰胆碱受体的效应器，可在大脑中传导钙信号。“钙-肉豆蔻酰基”开关涉及翻译后添加的肉豆蔻酰基部分与钙的结合，被认为可调节它们的膜结合能力，因此在其作用机制中起关键作用。在本研究中，我们利用空气/缓冲液界面的脂质单层，研究了膜组成和溶剂条件对两种VILIPs膜结合机制的影响。基于对肉豆蔻酰化和非肉豆蔻酰化蛋白吸附动力学比较的结果证实，钙和暴露的肉豆蔻酰基部分对于维持两种VILIPs的膜结合状态起着关键作用。然而，我们也观察到在没有钙和/或肉豆蔻酰基共轭的情况下，两种VILIP蛋白都有结合。我们提出了VILIP-1和VILIP-3的两阶段膜结合机制，即蛋白质最初通过静电相互作用以及可能与高度带负电荷的脂质头部基团的特异性相互作用被吸引到膜表面。共轭肉豆蔻酰基的挤出以及随后在膜中的锚定构成了结合机制的第二阶段，并确保了这些蛋白质持续的膜结合形式。
