Punnett's Square: Creature that Breaks Codon Rules

A microbe was discovered that used the codon UAG as a stop codon and as a code for the amino acid pyrrolysine. Pyrrolysine, found in archaea and bacteria, is required for methylamine-mediated methanogenesis, a form of anaerobic respiration. Typically, ambiguity in the code of DNA is deleterious, but with this microbe, it has created a new feature. This microbe has broken one of the fundamental rules of genetics, and biology as a whole, that each codon only has one meaning. The way that it is decided whether UAG will create the amino acid or to use it as a stop codon is seemingly random. The biggest connection that was found is that when less of the amino acid was around the cell, UAG more often acted as a stop codon. This study has created many questions around ways cells interpret stop codons, and if scientists have the ability to control them.