Thermostability of model protocell membranes
Thermostability of model protocell membranes
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DOI：
10.1073/pnas.0805086105
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发表时间：
2008-09-09
影响因子：
11.1
通讯作者：
Szostak, Jack W.
中科院分区：
文献类型：
--
作者：
Mansy, Sheref S.;Szostak, Jack W.
最早的细胞可能是由一个自我复制的遗传聚合物封装在一个自我复制的膜囊泡。在这里，我们表明，由简单的单链两亲分子，如脂肪酸，脂肪醇和脂肪酸甘油酯组成的囊泡是非常热稳定的，并保留内部RNA和DNA寡核苷酸在温度范围从0摄氏度到100摄氏度。包裹的双链DNA链可以通过在高温下变性而分离，同时保留在囊泡内，这意味着原始细胞中的链分离可能是由热波动介导的，而不会损失原始细胞的遗传物质。在升高的温度下，复杂的带电分子，如核苷酸非常迅速地穿过脂肪酸膜，这表明高温漂移可能在高级膜转运蛋白进化之前促进了营养素的吸收。这些膜的热稳定性是一致的封装的核酸的自发复制的交替在低温下的模板复制化学链分离和营养吸收在高温下。
The earliest cells may have consisted of a self-replicating genetic polymer encapsulated within a self-replicating membrane vesicle. Here, we show that vesicles composed of simple single-chain amphiphiles such as fatty acids, fatty alcohols, and fatty-acid glycerol esters are extremely thermostable and retain internal RNA and DNA oligonucleotides at temperatures ranging from 0 degrees C to 100 degrees C. The strands of encapsulated double-stranded DNA can be separated by denaturation at high temperature while being retained within vesicles, implying that strand separation in primitive protocells could have been mediated by thermal fluctuations without the loss of genetic material from the protocell. At elevated temperatures, complex charged molecules such as nucleotides cross fatty-acid-based membranes very rapidly, suggesting that high temperature excursions may have facilitated nutrient uptake before the evolution of advanced membrane transporters. The thermostability of these membranes is consistent with the spontaneous replication of encapsulated nucleic acids by the alternation of template-copying chemistry at low temperature with strand-separation and nutrient uptake at high temperature.