The Cation-π Box Is a Specific Phosphatidylcholine Membrane Targeting Motif
The Cation-π Box Is a Specific Phosphatidylcholine Membrane Targeting Motif
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DOI：
10.1074/jbc.m113.466532
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发表时间：
2013-05-24
影响因子：
4.8
通讯作者：
Roberts, Mary F.
中科院分区：
文献类型：
--
作者：
Cheng, Jiongjia;Goldstein, Rebecca;Roberts, Mary F.
外周膜蛋白可以通过磷脂头基的不同识别作用于特定的细胞器或质膜。尽管包括磷脂酰丝氨酸和磷脂酰肌醇在内的几个头基的特异性分子决定因素已经被很好地定义，但对两性离子磷脂酰胆碱(PC)头基的特异性识别还不是很清楚。在胞浆蛋白中，阳离子pi盒通过三甲基铵部分为胆碱的识别和结合提供了合适的受体。在PC中，这一部分可能提供足够的手柄通过阳离子pi笼与外围蛋白结合，其中两个或更多芳香族残基的pi系统与季胺的距离在4-5埃以内。我们通过将阳离子pi盒改造成缺乏特异性PC识别的金黄色葡萄球菌分泌的磷脂酰肌醇特异性磷脂酶C来证明这一假设。N254Y/H258Y突变体选择性地结合富含PC的囊泡，X射线结晶学表明N254Y/H258Y在阳离子pi基序中结合了胆碱和二丁酰磷脂酰胆碱。这种简单的PC识别基序可以被工程成各种各样的二级结构，为PC的特异性识别提供了一种普遍适用的方法。
Peripheral membrane proteins can be targeted to specific organelles or the plasma membrane by differential recognition of phospholipid headgroups. Although molecular determinants of specificity for several headgroups, including phosphatidylserine and phosphoinositides are well defined, specific recognition of the headgroup of the zwitterionic phosphatidylcholine (PC) is less well understood. In cytosolic proteins the cation-pi box provides a suitable receptor for choline recognition and binding through the trimethylammonium moiety. In PC, this moiety might provide a sufficient handle to bind to peripheral proteins via a cation-pi cage, where the pi systems of two or more aromatic residues are within 4-5 angstrom of the quaternary amine. We prove this hypothesis by engineering the cation-pi box into secreted phosphatidylinositol-specific phospholipase C from Staphylococcus aureus, which lacks specific PC recognition. The N254Y/H258Y variant selectively binds PC-enriched vesicles, and x-ray crystallography reveals N254Y/H258Y binds choline and dibutyroylphosphatidylcholine within the cation-pi motif. Such simple PC recognition motifs could be engineered into a wide variety of secondary structures providing a generally applicable method for specific recognition of PC.