Scientists Discover New Organism With DNA That Breaks Biological Rules
- Protists represent a highly diverse collection of eukaryotic organisms that are not classified as animals, plants, or fungi, encompassing microscopic single-celled life forms like amoebas and diatoms alongside...
- The unexpected finding emerged while researchers were testing a new DNA sequencing pipeline designed to handle extremely small amounts of genetic material from single cells.
- In the vast majority of living organisms, the standard genetic code utilizes three specific stop codons—TAA, TAG, and TGA—to act as punctuation marks that signal the end of...
Protists represent a highly diverse collection of eukaryotic organisms that are not classified as animals, plants, or fungi, encompassing microscopic single-celled life forms like amoebas and diatoms alongside large multicellular organisms like kelp. Within this varied group, ciliates such as Oligohymenophorea sp.
A Pond Water Sample Upends Central Dogma
Testing a New DNA Pipeline on a Freshwater Protist
The unexpected finding emerged while researchers were testing a new DNA sequencing pipeline designed to handle extremely small amounts of genetic material from single cells. Dr. Jamie McGowan, a postdoctoral scientist at the Earlham Institute, was studying the genome of a freshwater protist as part of the technical test. Instead of merely validating the sequencing method, the team identified the organism as a previously unknown species belonging to the group Oligohymenophorea, designated as Oligohymenophorea sp. PL0344.
Uncoupling Stop Codons in Gene Translation
In the vast majority of living organisms, the standard genetic code utilizes three specific stop codons—TAA, TAG, and TGA—to act as punctuation marks that signal the end of a gene and tell the cell where to stop building a protein.
This is extremely unusual, We’re not aware of any other case where these stop codons are linked to two different amino acids. It breaks some of the rules we thought we knew about gene translation — these two codons were thought to be coupled.
Dr. Jamie McGowan
In the newly identified protist species, only the TGA codon continues to function as a stop signal. The other two codons have been entirely repurposed during translation. According to the findings published in PLOS Genetics, the TAA codon now specifies lysine, while the TAG codon specifies glutamic acid.