Since there are only 20 possible amino acids, this means that there is some redundancy — several
different codons can encode for the same amino acid.
Because synthetic biologists can get the same amino acid from multiple codons, they can avoid troublesome DNA repeats by swapping in
different codons that achieve the same effect.
Brandis and Hughes changed many
different codons and showed that changing even a single codon in the gene for this protein into any one of the alternative «synonymous» codons reduced the «fitness» of Salmonella.
Not exact matches
Each instance will be replaced by a
different stop
codon, TAA.
To ensure novel genes can not be translated if they get passed on to other organisms, the team would have to go a step further and reassign the freed - up
codons so a
different amino acid to normal is added to a protein when they occur.
In separate experiments, they picked 13 other
codons and substituted them for alternatives with the same function across 42
different E. coli genes.
Even
codons for
different amino acids that have two of their three letters in common tend to translate into amino acids that share key chemical properties.
Here we report the in vivo transcription of DNA containing dNaM and dTPT3 into mRNAs with two
different unnatural
codons and tRNAs with cognate unnatural anticodons, and their efficient decoding at the ribosome to direct the site - specific incorporation of natural or non-canonical amino acids into superfolder green fluorescent protein.
This led to the eventual identification of a single nucleotide substitution in the second
codon of a previously unknown gene that is now known to be the cause of PRCD in at least 18
different breeds [23].