Delgado Sebastián, Armijo Álvaro, Bravo Verónica, Orellana Omar, Salazar Juan Carlos, Katz Assaf
Facultad de Ciencias, Universidad de Chile, Santiago, Chile.
Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile.
Front Microbiol. 2024 Aug 5;15:1412318. doi: 10.3389/fmicb.2024.1412318. eCollection 2024.
Despite the highly conserved nature of the genetic code, the frequency of usage of each codon can vary significantly. The evolution of codon usage is shaped by two main evolutionary forces: mutational bias and selection pressures. These pressures can be driven by environmental factors, but also by the need for efficient translation, which depends heavily on the concentration of transfer RNAs (tRNAs) within the cell. The data presented here supports the proposal that tRNA modifications play a key role in shaping the overall preference of codon usage in proteobacteria. Interestingly, some codons, such as CGA and AGG (encoding arginine), exhibit a surprisingly low level of variation in their frequency of usage, even across genomes with differing GC content. These findings suggest that the evolution of GC content in proteobacterial genomes might be primarily driven by changes in the usage of a specific subset of codons, whose usage is itself influenced by tRNA modifications.
尽管遗传密码具有高度保守性，但每个密码子的使用频率可能会有显著差异。密码子使用的进化受到两种主要进化力量的影响：突变偏向和选择压力。这些压力可能由环境因素驱动，也可能由高效翻译的需求驱动，而高效翻译在很大程度上取决于细胞内转运RNA（tRNA）的浓度。此处呈现的数据支持了这样一种观点，即tRNA修饰在塑造变形菌纲中密码子使用的总体偏好方面起着关键作用。有趣的是，一些密码子，如编码精氨酸的CGA和AGG，即使在GC含量不同的基因组中，其使用频率的变化水平也出奇地低。这些发现表明，变形菌纲基因组中GC含量的进化可能主要由特定密码子子集使用情况的变化驱动，而这些密码子的使用本身又受到tRNA修饰的影响。
