Universal Genetic Code and its Natural Variations


The universal genetic code is a common language for almost all organisms to translate nucleotide sequences of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) to amino acid sequences of proteins. However, the genetic code is still evolved. Nonuniversal genetic codes are found in some organisms and organelles. Aminoacyl‐transfer RNA (tRNA) synthetases and RNA modifications play a critical role in reassignment of the genetic code.

Keywords: universal genetic code; nonuniversal genetic code; posttranscriptional modification; recoding; polysemous codon; RNA editing

Figure 1.

(a) Base pairing between a tRNA anticodon and an mRNA codon. Base pairing between the base at position 34 of the tRNA (wobble base) and that at position 3 of a codon does not always conform to the Watson–Crick base‐pairing rule. (b) Wobble base pairings between first position of anticodons and third position of codons. GñU, IñA, IñC and IñU are wobble pairings. I stands for inosine. G–C pair is presented as a typical Watson–Crick base pair for comparison.

Figure 2.

Molecular mechanisms of frameshifts: (a) −1 frameshift, (b) +1 frameshift of E. coli RF2 and (c) +1 frameshift of antizyme. Without slippage and rebinding of peptidyl‐tRNA, aminoacyl‐tRNA binds to the A site, while a U base is skipped.



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Watanabe, Kimitsuna, and Suzuki, Tsutomu(Mar 2008) Universal Genetic Code and its Natural Variations. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0000810.pub2]