Prebiotic Vesicles Retain Solutes and Grow by Micelle Addition after Brief Cooling below the Membrane Melting Temperature
Prebiotic Vesicles Retain Solutes and Grow by Micelle Addition after Brief Cooling below the Membrane Melting Temperature
复制标题
益生元囊泡在膜熔化温度以下短暂冷却后通过添加胶束保留溶质并生长
DOI：
10.1021/acs.langmuir.2c01842
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发表时间：
2022
期刊：
影响因子：
3.9
通讯作者：
Keller, Sarah L.
中科院分区：
文献类型：
--
作者：
Cohen, Zachary R.;Todd, Zoe R.;Catling, David C.;Black, Roy A.;Keller, Sarah L.
RNA基因组在膜囊泡中的复制可能是早期地球原始细胞发育的关键步骤。接近0 °C的低温提高了RNA的稳定性，并允许有效的复制，而一些气候模型表明早期地球是寒冷的，因此第一个原始细胞可能出现在低温环境中。然而，在寒冷的温度下，饱和脂肪酸，这将是在早期地球上，形成凝胶相膜，是刚性的，并限制在双层内的流动性。原始细胞膜的两个主要作用是包裹溶质和通过从环境中引入额外的脂肪酸来生长。我们在这里测试是否在凝胶相的脂肪酸膜完成这些角色。我们发现，在0 °C附近，10碳两亲物的凝胶相膜与流体相膜一样有效地包封水性染料分子，但如果水溶液在-20 °C冷冻，内容物就会释放出来。凝胶相膜不增长可测量的胶束添加，但增长恢复时，膜被加热高于凝胶-液体转变温度。我们发现更长的12碳两亲物在0 °C附近不能保留包封的内容物。总之，我们的研究结果表明，原始细胞可能在经历暂时冷却低于膜熔化温度的环境中发育，并且当温度接近0 °C时，由相对短链脂肪酸组成的膜将更有效地包裹溶质。
Replication of RNA genomes within membrane vesicles may have been a critical step in the development of protocells on the early Earth. Cold temperatures near 0 °C improve the stability of RNA and allow efficient copying, while some climate models suggest a cold early Earth, so the first protocells may have arisen in cold-temperature environments. However, at cold temperatures, saturated fatty acids, which would have been available on the early Earth, form gel-phase membranes that are rigid and restrict mobility within the bilayer. Two primary roles of protocell membranes are to encapsulate solutes and to grow by incorporating additional fatty acids from the environment. We test here whether fatty acid membranes in the gel phase accomplish these roles. We find that gel-phase membranes of 10-carbon amphiphiles near 0 °C encapsulate aqueous dye molecules as efficiently as fluid-phase membranes do, but the contents are released if the aqueous solution is frozen at −20 °C. Gel-phase membranes do not grow measurably by micelle addition, but growth resumes when membranes are warmed above the gel–liquid transition temperature. We find that longer, 12-carbon amphiphiles do not retain encapsulated contents near 0 °C. Together, our results suggest that protocells could have developed within environments that experience temporary cooling below the membrane melting temperature, and that membranes composed of relatively short-chain fatty acids would encapsulate solutes more efficiently as temperatures approached 0 °C.