研究揭示RNA嘧啶和DNA嘌呤核苷的形成早於生命起源
作者：
小柯機器人發布時間：2020/6/5 9:14:00
英國劍橋生物醫學園區John D. Sutherland研究組近日取得一項新成果。他們揭示了RNA嘧啶和DNA嘌呤核苷在生命起源之前就已形成。該項研究成果在線發表在2020年6月3日的《自然》上。
研究人員完成了高效、立體、區域和呋喃糖基選擇性嘌呤脫氧核糖核苷——脫氧腺苷和脫氧肌苷的非生物合成。研究人員的合成方法使用了經典嘧啶核糖核苷（胞苷和尿苷）非生物合成中的關鍵中間體，並且發現一經合成，嘧啶在嘌呤脫氧核糖核苷的整個合成過程中一直存在，從而形成脫氧腺苷、脫氧肌苷、胞苷和尿苷。這些結果支持了嘌呤脫氧核糖核苷和嘧啶核糖核苷可能在生命出現之前並存的觀點。
研究人員表示，對第一個遺傳聚合物是什麼的爭論一直存在。儘管「 RNA世界」理論認為RNA是微生物存在之前的第一個可複製遺傳信息載體，早於生命開始之前。但其他證據表明，生命也可能始於異質核酸遺傳系統，其中包括RNA和DNA。這樣的理論簡化了最終從RNA中「同質DNA」作為主要遺傳信息存儲分子的「遺傳接管」機制，但是在相同的原始地球化學情況下，需要RNA和DNA結構單元的選擇性非生物合成。
附：英文原文
Title: Selective prebiotic formation of RNA pyrimidine and DNA purine nucleosides
Author: Jianfeng Xu, Vclav Chmela, Nicholas J. Green, David A. Russell, Mikoaj J. Janicki, Robert W. Gra, Rafa Szabla, Andrew D. Bond, John D. Sutherland
Issue&Volume: 2020-06-03
Abstract: The nature of the first genetic polymer is the subject of major debate1. Although the 『RNA world』 theory suggests that RNA was the first replicable information carrier of the prebiotic era—that is, prior to the dawn of life2,3—other evidence implies that life may have started with a heterogeneous nucleic acid genetic system that included both RNA and DNA4. Such a theory streamlines the eventual 『genetic takeover』 of homogeneous DNA from RNA as the principal information-storage molecule, but requires a selective abiotic synthesis of both RNA and DNA building blocks in the same local primordial geochemical scenario. Here we demonstrate a high-yielding, completely stereo-, regio- and furanosyl-selective prebiotic synthesis of the purine deoxyribonucleosides: deoxyadenosine and deoxyinosine. Our synthesis uses key intermediates in the prebiotic synthesis of the canonical pyrimidine ribonucleosides (cytidine and uridine), and we show that, once generated, the pyrimidines persist throughout the synthesis of the purine deoxyribonucleosides, leading to a mixture of deoxyadenosine, deoxyinosine, cytidine and uridine. These results support the notion that purine deoxyribonucleosides and pyrimidine ribonucleosides may have coexisted before the emergence of life5.
DOI: 10.1038/s41586-020-2330-9
Source: https://www.nature.com/articles/s41586-020-2330-9