RNA Oligomerization in Laboratory Analogues of Alkaline Hydrothermal Vent Systems
RNA Oligomerization in Laboratory Analogues of Alkaline Hydrothermal Vent Systems
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DOI：
10.1089/ast.2014.1280
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发表时间：
2015-07-01
期刊：
影响因子：
4.2
通讯作者：
McGown, Linda B.
中科院分区：
文献类型：
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作者：
Burcar, Bradley T.;Barge, Laura M.;McGown, Linda B.
在可行的益生菌条件下发现导致长链RNA形成的途径是证明RNA世界假说的可行性的关键一步。大量的研究工作已经提供了通过使用环状核糖核苷酸、咪唑活化的蒙脱土催化剂的核糖核苷酸以及在脂质存在下的核糖核苷酸进行RNA寡聚的证据。此外，矿物表面，如硼酸盐、磷灰石和方解石，已被证明可以催化无机前体形成小的有机化合物(克里夫斯，2008年)，这表明可能是生命起源的地质地点。事实上，这些特殊矿物的催化性能提供了令人信服的证据，证明碱性热液喷口是生命起源的潜在地点，因为在这些喷口，可以形成巨大的富含金属的烟囱结构，已被证明对各种形式的生命具有能量优势。在这里，我们测试了富含铁和硫的烟囱使用咪唑激活的和非激活的核苷酸支持RNA齐聚反应的能力。这些烟囱是在实验室的海洋水溶液中合成的，条件与目前对早期地球的理解一致。考察了元素组成、pH值、蒙脱石催化粘土包裹体、小分子有机物掺杂烟囱、原位核糖核酸活化等因素对RNA聚合的影响。这些实验表明，在某些条件下，使用未经修饰的核糖核苷酸成功地进行了二聚反应，当使用咪唑激活的核糖核苷酸时，RNA寡聚体的长度可达4个单位。对烟囱沉淀物和反应溶液的元素分析表明，所测定的大多数金属阳离子优先分配到烟囱中。
Discovering pathways leading to long-chain RNA formation under feasible prebiotic conditions is an essential step toward demonstrating the viability of the RNA World hypothesis. Intensive research efforts have provided evidence of RNA oligomerization by using circular ribonucleotides, imidazole-activated ribonucleotides with montmorillonite catalyst, and ribonucleotides in the presence of lipids. Additionally, mineral surfaces such as borates, apatite, and calcite have been shown to catalyze the formation of small organic compounds from inorganic precursors (Cleaves, 2008), pointing to possible geological sites for the origins of life. Indeed, the catalytic properties of these particular minerals provide compelling evidence for alkaline hydrothermal vents as a potential site for the origins of life since, at these vents, large metal-rich chimney structures can form that have been shown to be energetically favorable to diverse forms of life. Here, we test the ability of iron- and sulfur-rich chimneys to support RNA oligomerization reactions using imidazole-activated and non-activated ribonucleotides. The chimneys were synthesized in the laboratory in aqueous ocean solutions under conditions consistent with current understanding of early Earth. Effects of elemental composition, pH, inclusion of catalytic montmorillonite clay, doping of chimneys with small organic compounds, and in situ ribonucleotide activation on RNA polymerization were investigated. These experiments, under certain conditions, showed successful dimerization by using unmodified ribonucleotides, with the generation of RNA oligomers up to 4 units in length when imidazole-activated ribonucleotides were used instead. Elemental analysis of the chimney precipitates and the reaction solutions showed that most of the metal cations that were determined were preferentially partitioned into the chimneys.