Oxford Protist Reassigns 2 Stop Codons to Different Amino Acids
Updated
Updated · inkorr.com · Oct 11
Oxford Protist Reassigns 2 Stop Codons to Different Amino Acids
2 articles · Updated · inkorr.com · Oct 11
Summary
Oligohymenophorea sp. PL0344, found in an Oxford freshwater pond, uses TAA to encode lysine and TAG to encode glutamic acid, leaving TGA as its only conventional stop signal.
A novel low-input DNA sequencing method exposed the anomaly, and genome analysis found specialized tRNA genes tied to TAA and TAG plus frequent TGA stops after coding regions.
The result breaks a long-standing pattern: when TAA and TAG stop codons are reassigned in other organisms, they typically evolve together to specify the same amino acid.
Related studies have found other ciliate code changes—including UAG likely coding for leucine in three uncultivated species—suggesting such rewiring evolved independently at least three times.
Researchers said the finding could sharpen understanding of genetic-code evolution and aid synthetic biology efforts to reprogram cells and design novel proteins.