Key Laboratory of Child Development and Learning Science of Ministry of Education of China, Southeast University, Nanjing, Jiangsu, China.
PLoS Comput Biol. 2010 Feb 5;6(2):e1000664. doi: 10.1371/journal.pcbi.1000664.
Recent studies have suggested that the thermodynamic stability of mRNA secondary structure near the start codon can regulate translation efficiency in Escherichia coli, and that translation is more efficient the less stable the secondary structure. We survey the complete genomes of 340 species for signals of reduced mRNA secondary structure near the start codon. Our analysis includes bacteria, archaea, fungi, plants, insects, fishes, birds, and mammals. We find that nearly all species show evidence for reduced mRNA stability near the start codon. The reduction in stability generally increases with increasing genomic GC content. In prokaryotes, the reduction also increases with decreasing optimal growth temperature. Within genomes, there is variation in the stability among genes, and this variation correlates with gene GC content, codon bias, and gene expression level. For birds and mammals, however, we do not find a genome-wide trend of reduced mRNA stability near the start codon. Yet the most GC rich genes in these organisms do show such a signal. We conclude that reduced stability of the mRNA secondary structure near the start codon is a universal feature of all cellular life. We suggest that the origin of this reduction is selection for efficient recognition of the start codon by initiator-tRNA.
最近的研究表明，mRNA 二级结构在起始密码子附近的热力学稳定性可以调节大肠杆菌中的翻译效率，二级结构越不稳定，翻译效率越高。我们调查了 340 个物种的完整基因组，以寻找起始密码子附近 mRNA 二级结构减少的信号。我们的分析包括细菌、古菌、真菌、植物、昆虫、鱼类、鸟类和哺乳动物。我们发现，几乎所有的物种在起始密码子附近都有减少 mRNA 稳定性的证据。稳定性的降低通常随着基因组 GC 含量的增加而增加。在原核生物中，这种减少也随着最适生长温度的降低而增加。在基因组中，基因之间的稳定性存在差异，这种差异与基因 GC 含量、密码子偏好和基因表达水平相关。然而，对于鸟类和哺乳动物，我们没有发现起始密码子附近 mRNA 稳定性降低的全基因组趋势。然而，这些生物中 GC 含量最丰富的基因确实表现出了这样的信号。我们得出结论，起始密码子附近 mRNA 二级结构稳定性的降低是所有细胞生命的普遍特征。我们认为，这种减少的起源是为了有效地识别起始密码子的起始 tRNA。
