Phospholipid membranes form cellular barriers but need to be flexible enough to divide by fission. Phospholipids generally contain a saturated fatty acid (FA) at position sn1 whereas the sn2-FA is saturated, monounsaturated or polyunsaturated. Our understanding of the impact of phospholipid unsaturation on membrane flexibility and fission is fragmentary. Here, we provide a comprehensive view of the effects of the FA profile of phospholipids on membrane vesiculation by dynamin and endophilin. Coupled to simulations, this analysis indicates that: (i) phospholipids with two polyunsaturated FAs make membranes prone to vesiculation but highly permeable; (ii) asymmetric sn1-saturated-sn2-polyunsaturated phospholipids provide a tradeoff between efficient membrane vesiculation and low membrane permeability; (iii) When incorporated into phospholipids, docosahexaenoic acid (DHA; omega-3) makes membranes more deformable than arachidonic acid (omega-6). These results suggest an explanation for the abundance of sn1-saturated-sn2-DHA phospholipids in synaptic membranes and for the importance of the omega-6/omega-3 ratio on neuronal functions.

中文翻译：

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脑磷脂的酰基链不对称和多不饱和促进膜泡形成而不渗漏

磷脂膜形成细胞屏障，但需要足够柔韧以通过裂变分裂。磷脂通常在位置 sn1 处含有饱和脂肪酸 (FA)，而 sn2-FA 是饱和的、单不饱和的或多不饱和的。我们对磷脂不饱和度对膜柔韧性和裂变影响的理解是零碎的。在这里，我们全面介绍了磷脂的 FA 谱对动力蛋白和内啡肽的膜泡形成的影响。与模拟相结合，该分析表明：（i）具有两种多不饱和 FA 的磷脂使膜易于形成囊泡，但具有高渗透性；(ii) 不对称 sn1-饱和-sn2-多不饱和磷脂在有效的膜泡形成和低膜通透性之间提供权衡；(iii) 当掺入磷脂时，二十二碳六烯酸 (DHA; omega-3) 使膜比花生四烯酸 (omega-6) 更易变形。这些结果解释了突触膜中 sn1-饱和-sn2-DHA 磷脂的丰度以及 omega-6/omega-3 比率对神经元功能的重要性。