Rebaud Samuel, Wang Conan K, Sarkis Joe, Mason Lyndel, Simon Anne, Blum Loïc J, Hofmann Andreas, Girard-Egrot Agnès P
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 for Cell and Molecular Therapies, Griffith University, Brisbane Qld 4111, Australia.
Biochim Biophys Acta. 2014 Oct;1838(10):2698-707. doi: 10.1016/j.bbamem.2014.06.021. Epub 2014 Jul 11.
VIsinin-LIke Proteins (VILIPs) are a subfamily of the Neuronal Calcium Sensor (NCS) proteins, which possess both N-myristoylation and EF-hand motifs allowing for a putative 'calcium-myristoyl switch' regulation mechanism. It has previously been established that myristoyl conjugation increases the affinity of proteins for membranes, but, in many cases, a second feature such as a cluster of positively-charged residues is needed for stable membrane binding. The interaction of two members of this family, VILIP-1 and VILIP-3, with Langmuir monolayers as membrane models has been investigated in order to study the effects of both myristoylation and the highly basic region containing conserved poly-lysine residues on membrane association kinetics and binding properties. Results show that in the presence of calcium, N-myristoylation significantly increases the kinetic rate of VILIP adsorption to the membrane. Additionally, the proteins bind to negatively charged phospholipids independently of the conjugated myristate moiety. Besides the regulatory effect of calcium on the rate of binding presumably due to exposure of the myristoyl moiety ascribed to their putative 'calcium-myristoyl switch', VILIP-1 and -3 also engage specific interactions with biomimetic membranes containing phosphatidylinositol 4,5-bisphosphate (PIP2). The presence of PIP2 increases the membrane association rates of both VILIPs. Taken together, these results show the major kinetic role of N-myristoylation for membrane binding, and highlight the critical role of specific phosphoinositide interactions for membrane association of members of the VILIP family.
类视锥蛋白（VILIPs）是神经元钙传感器（NCS）蛋白的一个亚家族，它们同时具有N-肉豆蔻酰化和EF手基序，从而形成一种假定的“钙-肉豆蔻酰开关”调节机制。此前已经确定，肉豆蔻酰共轭作用会增加蛋白质对膜的亲和力，但在许多情况下，稳定的膜结合还需要第二个特征，比如一簇带正电荷的残基。为了研究肉豆蔻酰化以及含有保守多聚赖氨酸残基的高碱性区域对膜结合动力学和结合特性的影响，该家族的两个成员VILIP-1和VILIP-3与作为膜模型的朗缪尔单层膜之间的相互作用已得到研究。结果表明，在有钙存在的情况下，N-肉豆蔻酰化显著提高了VILIP吸附到膜上的动力学速率。此外，这些蛋白质独立于共轭的肉豆蔻酸部分与带负电荷的磷脂结合。除了钙对结合速率的调节作用可能是由于其假定的“钙-肉豆蔻酰开关”导致肉豆蔻酰部分暴露之外，VILIP-1和-3还与含有磷脂酰肌醇4,5-二磷酸（PIP2）的仿生膜发生特异性相互作用。PIP2的存在提高了两种VILIP的膜结合速率。综上所述，这些结果表明N-肉豆蔻酰化在膜结合中起主要的动力学作用，并突出了特定磷酸肌醇相互作用对VILIP家族成员膜结合的关键作用。
