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arXiv 2210.09666q-bio.PE
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稀有事件采样分析揭示遗传密码的适应度景观

Rare-Event Sampling Analysis Uncovers the Fitness Landscape of the Genetic Code

Yuji Omachi, Nen Saito, Chikara Furusawa

AI总结:

本研究利用稀有事件采样方法分析遗传密码的适应度景观,发现标准遗传密码极为鲁棒,且景观具有多峰结构,进化路径依赖地偏向特定峰。

摘要:

遗传密码是指将64个密码子映射到20种氨基酸的规则。除少数例外,几乎所有生物体都共享相同的遗传密码,即标准遗传密码(SGC)。虽然尚不清楚这一通用密码为何在进化过程中产生并被维持,但它可能是在选择压力下被保留下来的。理论研究比较了SGC与数值生成的假设性随机遗传密码,表明SGC一直受到强选择压力,以使其对翻译错误具有鲁棒性。然而,由于计算时间的限制,这些先前的研究仅在可能的密码空间的一个小子空间中搜索随机遗传密码。因此,遗传密码如何进化以及遗传密码适应度景观的特征仍不清楚。通过应用多重正则蒙特卡洛方法(一种高效的稀有事件采样方法),我们从比先前研究更广泛的随机遗传密码集合中高效地采样了随机密码,估计每$10^{20}$个随机密码中只有一个比SGC更鲁棒。这一估计显著小于先前的估计(百万分之一)。我们还刻画了遗传密码的适应度景观,该景观具有四个主要的适应度峰,其中一个包含SGC。此外,遗传算法分析表明,在这种多峰适应度景观下的进化可能以路径依赖的方式强烈偏向于一个狭窄的峰。

英文摘要:

The genetic code refers to a rule that maps 64 codons to 20 amino acids. Nearly all organisms, with few exceptions, share the same genetic code, the standard genetic code (SGC). While it remains unclear why this universal code has arisen and been maintained during evolution, it may have been preserved under selection pressure. Theoretical studies comparing the SGC and numerically created hypothetical random genetic codes have suggested that the SGC has been subject to strong selection pressure for being robust against translation errors. However, these prior studies have searched for random genetic codes in only a small subspace of the possible code space due to limitations in computation time. Thus, how the genetic code has evolved, and the characteristics of the genetic code fitness landscape, remain unclear. By applying multicanonical Monte Carlo, an efficient rare-event sampling method, we efficiently sampled random codes from a much broader random ensemble of genetic codes than in previous studies, estimating that only one out of every $10^{20}$ random codes is more robust than the SGC. This estimate is significantly smaller than the previous estimate, one in a million. We also characterized the fitness landscape of the genetic code that has four major fitness peaks, one of which includes the SGC. Furthermore, genetic algorithm analysis revealed that evolution under such a multi-peaked fitness landscape could be strongly biased toward a narrow peak, in an evolutionary path-dependent manner.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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