JBC：温水中成功合成长链RNA分子

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数亿年前DNA和RNA分子是如何从简单的单体聚合而成的一直是困扰生物分子起源的一个难题。不过近日，意大利的研究人员重建了这一早期进化过程，仅仅在温水存在的反应条件下就使得简单的核苷酸聚合成了长链的RNA分子。! w/ W) _) Y3 ~1 y0 F

5 G! j4 G. `8 l  z& r大多数的研究人员相信RNA分子是在DNA和蛋白质之前出现的第一种生物大分子，但是很少有人成功的在生命起源以前的环境下将简单的单体分子构建成为RNA分子。
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Ernesto Di Mauro和他的同事发现在40-90°C的水中，环核苷酸这一古老的分子能够聚合成为长度超过100bp的分子，而这一水温恰好与生命出现以前地球上水的温度相同。
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2 X5 J; R9 {0 y# A4 t, j' b+ j环核苷酸与构成DNA和RNA分子的核苷酸单体十分相似，只是在结构上多出了一个化学键而形成了环状结构。正是这个额外的化学键使得环核苷酸具有了较高的反应活性，使得他们能够在一定的速率下（每聚合100bp需要200小时）聚合成为长链核酸分子。1 |0 ^* T4 v* Q  C5 W, u

: h. F! _2 z) {/ [由于环核苷酸可以较为容易的通过甲酰胺等简单的化合物分子反应而形成，因此这使得环核苷酸在生命前期的地球环境中的大量存在成为可能。这个研究发现可能揭开了第一个基因组是如何产生的谜题。（生物谷Bioon.com）/ r* K) ^2 t! T* M4 G+ D
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生物谷推荐原始出处：* \" i: W7 h$ B4 V; Y6 D
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JBC October 2, 2009, doi: 10.1074/jbc.M109.041905
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Generation of Long RNA Chains in Water*
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. `; p- }2 r. O( E) GGiovanna Costanzo?,1, Samanta Pino§,1, Fabiana Ciciriello§ and Ernesto Di Mauro?,2
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6 C# j' R) r& A9 R% MFrom the ?Istituto di Biologia e Patologia Molecolari, CNR,; S* s& W) S: M
the §Dipartimento di Genetica e Biologia Molecolare, Università La Sapienza di Roma, and4 S& O1 Z- D/ v  F# ]3 s
the ?Fondazione Istituto Pasteur-Fondazione Cenci-Bolognetti, c/o Dipartimento di Genetica e Biologia Molecolare, Università La Sapienza di Roma, P. le Aldo Moro, 5, Rome 00185, Italy, q, p  o* Y! G- W" @9 q" `3 v

( G* G+ j, h" n+ d% N6 _9 b* OThe synthesis of RNA chains from 3′,5′-cAMP and 3′,5′-cGMP was observed. The RNA chains formed in water, at moderate temperatures (40–90 °C), in the absence of enzymes or inorganic catalysts. As determined by RNase analyses, the bonds formed were canonical 3′,5′-phosphodiester bonds. The polymerizations are based on two reactions not previously described: 1) oligomerization of 3′, 5′-cGMP to ～25-nucleotide-long RNA molecules, and of 3′,5′-cAMP to 4- to 8-nucleotide-long molecules. Oligonucleotide A molecules were further extended by reciprocal terminal ligation to yield RNA molecules up to >120 nucleotides long and 2) chain extension by terminal ligation of newly polymerized products of 3′,5′-cGMP on preformed oligonucleotides. The enzyme- and template-independent synthesis of long oligomers in water from prebiotically affordable precursors approaches the concept of spontaneous generation of (pre)genetic information.