Expanded genetic code

An expanded genetic code is an artificially modified <a href="/facts/Genetic_code/zUK0bY1B">genetic code</a> in which one or more specific <a href="/facts/Codon/zUK0bY1B">codons</a> have been re-allocated to encode an <a href="/facts/Amino_acid/WDxYwBny">amino acid</a> that is not among the 22 common naturally-encoded <a href="/facts/Proteinogenic_amino_acid/xoXITvm0">proteinogenic amino acids</a>.
The key prerequisites to expand the genetic code are:

<ul><li>the <a href="/facts/Non-proteinogenic_amino_acids/KRQb1dK6">non-standard amino acid</a> to encode,</li>
<li>an unused codon to adopt,</li>
<li>a <a href="/facts/TRNA/pR9T5XSl">tRNA</a> that recognizes this codon, and</li>
<li>a <a href="/facts/TRNA_synthetase/HkDeI8bN">tRNA synthetase</a> that recognizes only that tRNA and only the non-standard amino acid.</li></ul>
Expanding the genetic code is an area of research of <a href="/facts/Synthetic_biology/rHSNe8j3">synthetic biology</a>, an applied biological discipline whose goal is to engineer living systems for useful purposes. The genetic code expansion enriches the repertoire of useful tools available to science.
In May 2019, researchers, in a milestone effort, reported the creation of a new <a href="/facts/Synthetic_biology/rHSNe8j3">synthetic</a> (possibly <a href="/facts/Artificial_life/YcA6tvfe">artificial</a>) form of viable <a href="/facts/Life/DNw7NUId">life</a>, a variant of the <a href="/facts/Bacteria/wC8xSCsU">bacteria</a> <a href="/facts/Escherichia_coli/nR4Gvl56">Escherichia coli</a>, by reducing the natural number of 64 <a href="/facts/Codon/zUK0bY1B">codons</a> in the bacterial <a href="/facts/Genome/31Sm08JT">genome</a> to 61 codons (eliminating two out of the six codons coding for <a href="/facts/Serine/4duVl30B">serine</a> and one out of three <a href="/facts/Stop_codon/1yuAkq9X">stop codons</a>) – of which 59 used to encode 20 <a href="/facts/Amino_acid/WDxYwBny">amino acids</a>.

Expanded genetic code open-in-new

Expanded genetic code