![Recombination transferred part of archaeal YRS into non-canonical bacterial YRS. A) YRS core catalytic domain alignment from archaeal (indicated left as blue), bacterial non-canonical (purple) and bacterial canonical (pink) sequences. Both recombinant and nonrecombinant YRSs are found within all four major bacterial supergroups (Terrabacteria, Proteobacteria, PVC and FCB) B) Speciestree reconciled consensus trees reconstructed for the non-recombinant (left) and recombinant YRS sites (right). Branch lengths were estimated using NQ.bac+R10 in IQ-Tree v2.1.332. -- [biorxiv.org]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/07/Tryptophan-became.png?resize=1200%2C720&ssl=1)
[biorxiv.org] We evaluate whether tryptophan (W), widely thought to be the last of the 20 canonical amino acids added to the genetic code, was already present in the Last Universal […]
Last Universal Common Ancestor (LUCA)
![Outline of construction of plasmids carrying LUCA and E. coli tRNA genes and codon test genes. A LUCA and E. coli tRNA genes. Pairs of tRNA genes from E. coli and LUCA with identical anticodon sequences were synthesized. Primers (Supplementary Table S2) were used to amplify the transcription templates for in vitro synthesis. B Codon test genes. The constructs were based on the pET23a vector. Test genes were inserted between the NdeI and BamHI sites, with the start codons included in the NdeI site. -- [Journal of Molecular Evolution]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/07/Resurrecting-tRNAs.png?resize=1200%2C716&ssl=1)
Posted inOrigin & Evolution of Life
Resurrecting tRNAs of the Last Universal Common Ancestor (Commonote) Toward Rebuilding the Ancient Translation System
[Journal of Molecular Evolution] Ancestral sequence reconstruction (ASR) was used to study the evolution of the translational system by inferring tRNA sequences of the Last Archaeal Common Ancestor (LACA), the […]