University Joseph Fourier of Grenoble, TIMC-IMAG UMR UJF/CNRS 5525, Faculty of Medicine, 38700 La Tronche, France.
Departamento de Informática, Universidad Federico Santa María, Casilla 110-V, Valparaíso, Chile.
Int J Mol Sci. 2009 Jul 31;10(8):3420-3441. doi: 10.3390/ijms10083420.
A number of small RNA sequences, located in different non-coding sequences and highly preserved across the tree of life, have been suggested to be molecular fossils, of ancient (and possibly primordial) origin. On the other hand, recent years have revealed the existence of ubiquitous roles for small RNA sequences in modern organisms, in functions ranging from cell regulation to antiviral activity. We propose that a single thread can be followed from the beginning of life in RNA structures selected only for stability reasons through the RNA relics and up to the current coevolution of RNA sequences; such an understanding would shed light both on the history and on the present development of the RNA machinery and interactions. After presenting the evidence (by comparing their sequences) that points toward a common thread, we discuss a scenario of genome coevolution (with emphasis on viral infectious processes) and finally propose a plan for the reevaluation of the stereochemical theory of the genetic code; we claim that it may still be relevant, and not only for understanding the origin of life, but also for a comprehensive picture of regulation in present-day cells.
一些小 RNA 序列位于不同的非编码序列中，在生命之树上高度保守，被认为是分子化石，具有古老（可能是原始）的起源。另一方面，近年来的研究揭示了小 RNA 序列在现代生物中的普遍作用，其功能范围从细胞调节到抗病毒活性。我们提出，从 RNA 结构的起源开始，就可以沿着一条单一的线索进行研究，这些 RNA 结构仅由于稳定性原因而被选择，然后通过 RNA 遗迹一直到当前 RNA 序列的共同进化；这种理解不仅可以揭示 RNA 机制和相互作用的历史，还可以揭示其当前的发展。在提出指向共同线索的证据（通过比较它们的序列）之后，我们讨论了基因组共同进化的情景（重点是病毒感染过程），最后提出了重新评估遗传密码的立体化学理论的计划；我们声称，它可能仍然具有相关性，不仅对于理解生命的起源，而且对于当今细胞的全面调控图景都是如此。
