Structural Chemistry Program, Eskitis Institute for Cell & Molecular Therapies, Griffith University, Brisbane, Queensland, Australia.
PLoS One. 2011;6(11):e26793. doi: 10.1371/journal.pone.0026793. Epub 2011 Nov 2.
The NCS protein Visinin-like Protein 1 (VILIP-1) transduces calcium signals in the brain and serves as an effector of the non-retinal receptor guanylyl cyclases (GCs) GC-A and GC-B, and nicotinic acetyl choline receptors (nAchR). Analysis of the quaternary structure of VILIP-1 in solution reveals the existence of monomeric and dimeric species, the relative contents of which are affected but not exclusively regulated by divalent metal ions and Redox conditions. Using small-angle X-ray scattering, we have investigated the low resolution structure of the calcium-bound VILIP-1 dimer under reducing conditions. Scattering profiles for samples with high monomeric and dimeric contents have been obtained. The dimerization interface involves residues from EF-hand regions EF3 and EF4.Using monolayer adsorption experiments, we show that myristoylated and unmyristoylated VILIP-1 can bind lipid membranes. The presence of calcium only marginally improves binding of the protein to the monolayer, suggesting that charged residues at the protein surface may play a role in the binding process.In the presence of calcium, VILIP-1 undergoes a conformational re-arrangement, exposing previously hidden surfaces for interaction with protein partners. We hypothesise a working model where dimeric VILIP-1 interacts with the membrane where it binds membrane-bound receptors in a calcium-dependent manner.
NCS 蛋白类视蛋白样蛋白 1（VILIP-1）在大脑中传递钙信号，作为非视网膜受体鸟苷酸环化酶（GCs）GC-A 和 GC-B 以及烟碱型乙酰胆碱受体（nAchR）的效应物。对溶液中 VILIP-1 四级结构的分析表明，存在单体和二聚体两种形式，其相对含量受二价金属离子和氧化还原条件的影响，但不受其完全调控。我们使用小角 X 射线散射研究了还原条件下结合钙的 VILIP-1 二聚体的低分辨率结构。获得了具有高单体和二聚体含量的样品的散射曲线。二聚体化界面涉及 EF 手区域 EF3 和 EF4 的残基。通过单层吸附实验，我们表明豆蔻酰化和非豆蔻酰化的 VILIP-1 可以结合脂质膜。钙的存在仅略微改善了蛋白质与单层的结合，这表明蛋白质表面的带电残基可能在结合过程中起作用。在钙存在下，VILIP-1 经历构象重排，暴露出以前隐藏的与蛋白质伴侣相互作用的表面。我们假设一个工作模型，其中二聚体 VILIP-1与膜相互作用，以钙依赖的方式与膜结合的受体结合。
