The Curvature Sensitivity of a Membrane-Binding Amphipathic Helix Can Be Modulated by the Charge on a Flanking Region
The Curvature Sensitivity of a Membrane-Binding Amphipathic Helix Can Be Modulated by the Charge on a Flanking Region
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DOI：
10.1021/bi401457r
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发表时间：
2014-01-28
期刊：
影响因子：
2.9
通讯作者：
Cornell, Rosemary B.
中科院分区：
文献类型：
--
作者：
Chong, Sharon S. Y.;Taneva, Svetla G.;Cornell, Rosemary B.
膜诱导的两亲性螺旋（m-AH）可以通过优先结合富含曲面的疏水性脂质包装缺陷来充当膜曲率传感器。当静电相互作用较弱时，对疏水性和膜曲率的依赖性增强。我们探讨了修饰膜和蛋白质电荷对两种含m-AH的蛋白质CTP：磷酸胆碱胞苷酰转移酶（CCT）和α-突触核蛋白（α-syn）的曲率感知的作用。这两种蛋白质中的m-AH结构域两侧是具有多个磷酸丝氨酸（CCT）或酸性残基（α-syn）的无序尾部，我们将其突变为谷氨酸或丝氨酸以修饰蛋白质电荷。结合不同曲率的囊泡的分析表明，增加尾部区域的负电荷降低结合强度，并增强曲率依赖性，特别是对于CCT。我们把这归因于电荷排斥。相反，增加膜负电荷抑制曲率依赖性。我们的数据表明，歧视弯曲与平坦的膜与高负电荷可以调制磷酸化。
Membrane-induced amphipathic helices (m-AH) can act as membrane curvature sensors by binding preferentially to hydrophobic lipid packing defects enriched in curved surfaces. Reliance on hydrophobicity and membrane curvature for binding is enhanced when electrostatic interactions are weak. We probed the role of modifying membrane and protein charge on the curvature sensing of two m-AH-containing proteins, CTP:phosphocholine cytidylyltransferase (CCT) and alpha-synuclein (alpha-syn). The m-AH domains in both proteins are flanked by disordered tails with multiple phosphoserines (CCT) or acidic residues (alpha-syn), which we mutated to glutamate or serine to modify protein charge. Analysis of binding to vesicles of varying curvature showed that increasing the negative charge of the tail region decreased the binding strength and augmented the curvature dependence, especially for CCT. We attribute this to charge repulsion. Conversely, increasing the membrane negative charge dampened the curvature dependence. Our data suggest that discrimination of curved versus flat membranes with high negative charge could be modulated by phosphorylation.