The Jack H Skirball Center for Chemical Biology and Proteomics, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA.
Proc Natl Acad Sci U S A. 2010 May 4;107(18):8298-303. doi: 10.1073/pnas.1000704107. Epub 2010 Apr 12.
The establishment of the genetic code remains elusive nearly five decades after the code was elucidated. The stereochemical hypothesis postulates that the code developed from interactions between nucleotides and amino acids, yet supporting evidence in a biological context is lacking. We show here that anticodons are selectively enriched near their respective amino acids in the ribosome, and that such enrichment is significantly correlated with the canonical code over random codes. Ribosomal anticodon-amino acid enrichment further reveals that specific codons were reassigned during code evolution, and that the code evolved through a two-stage transition from ancient amino acids without anticodon interaction to newer additions with anticodon interaction. The ribosome thus serves as a molecular fossil, preserving biological evidence that anticodon-amino acid interactions shaped the evolution of the genetic code.
遗传密码的建立在密码阐明近五十年后仍然难以捉摸。立体化学假说假设密码是由核苷酸和氨基酸之间的相互作用发展而来的，但在生物背景下缺乏支持证据。我们在这里表明，反密码子在核糖体中与其各自的氨基酸附近选择性富集，并且这种富集与规范密码与随机密码相比具有显著相关性。核糖体反密码子-氨基酸富集进一步表明，在密码进化过程中特定的密码子被重新分配，并且密码通过从没有反密码子相互作用的古老氨基酸到具有反密码子相互作用的较新添加物的两个阶段过渡而进化。因此，核糖体充当分子化石，保存了反密码子-氨基酸相互作用塑造遗传密码进化的生物学证据。
