PDF(Pubmed)
Abstract：
The genetic code consists of 61 codons coding for 20 amino acids. These codons are recognized by transfer RNAs (tRNAs) that bind to specific codons during protein synthesis. All organisms utilize less than all 61 possible anticodons due to base pair wobble: the ability to have a mismatch with a codon at its third nucleotide. Previous studies observed a correlation between the tRNA pool of bacteria and the temperature of their respective environments. However, it is unclear if these patterns represent biological adaptations to maintain the efficiency and accuracy of protein synthesis in different environments. A mechanistic mathematical model of mRNA translation is used to quantify the expected elongation rates and error rate for each codon based on an organism\'s tRNA pool. A comparative analysis across a range of bacteria that accounts for covariance due to shared ancestry is performed to quantify the impact of environmental temperature on the evolution of the tRNA pool. We find that thermophiles generally have more anticodons represented in their tRNA pool than mesophiles or psychrophiles. Based on our model, this increased diversity is expected to lead to increased missense errors. The implications of this for protein evolution in thermophiles are discussed.
摘要：
遗传密码由61个编码20个氨基酸的密码子组成。这些密码子由在蛋白质合成过程中与特定密码子结合的转移RNA(tRNA)识别。由于碱基对摆动,所有生物体利用少于全部61种可能的反密码子:与密码子在其第三个核苷酸处具有错配的能力。先前的研究观察到细菌的tRNA池与其各自环境的温度之间存在相关性。然而,目前尚不清楚这些模式是否代表生物适应，以维持不同环境中蛋白质合成的效率和准确性。mRNA翻译的机械数学模型用于基于生物体的tRNA池定量每个密码子的预期伸长率和错误率。对一系列细菌进行比较分析，以量化环境温度对tRNA库进化的影响。我们发现，嗜热菌通常比中温菌或嗜冷菌在其tRNA池中代表更多的反密码子。根据我们的模型,这种增加的多样性预计会导致错觉错误的增加。讨论了这对嗜热菌中蛋白质进化的影响。
