Membrane growth can generate a transmembrane pH gradient in fatty acid vesicles
Membrane growth can generate a transmembrane pH gradient in fatty acid vesicles
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DOI：
10.1073/pnas.0308045101
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发表时间：
2004-05-25
影响因子：
11.1
通讯作者：
Szostak, JW
中科院分区：
文献类型：
--
作者：
Chen, IA;Szostak, JW
电化学质子梯度是现代细胞能量转导的基础，甚至在最早的细胞样结构中也可能发挥着重要作用。我们研究了脂肪酸囊泡（早期细胞膜的模型）膜上维持 pH 梯度的条件。我们发现，在碱金属阳离子存在的情况下，这种膜上的 pH 梯度会迅速衰减，但在不存在渗透性阳离子的情况下可以保持不变。在这种条件下，当脂肪酸囊泡通过掺入额外的脂肪酸而生长时，自发地产生跨膜pH梯度。这种 pH 梯度的形成捕获了膜生长过程中释放的一些能量，但也阻碍和限制了膜面积的进一步增加。一旦膜成分进化到能够维持稳定的 pH 梯度，膜生长与能量储存的耦合可能为早期细胞提供生长优势。
Electrochemical proton gradients are the basis of energy transduction in modern cells, and may have played important roles in even the earliest cell-like structures. We have investigated the conditions under which pH gradients are maintained across the membranes of fatty acid vesicles, a model of early cell membranes. We show that pH gradients across such membranes decay rapidly in the presence of alkali-metal cations, but can be maintained in the absence of permeable cations. Under such conditions, when fatty acid vesicles grow through the incorporation of additional fatty acid, a transmembrane pH gradient is spontaneously generated. The formation of this pH gradient captures some of the energy released during membrane growth, but also opposes and limits further membrane area increase. The coupling of membrane growth to energy storage could have provided a growth advantage to early cells, once the membrane composition had evolved to allow the maintenance of stable pH gradients.