In a surprise discovery, researchers working on a novel DNA sequencing technique found an unexpected change in our grasp of genetics.
The genome of a protist, analyzed by Dr. Jamie McGowan, a postdoctoral scientist at the Earlham Institute, has shown a unique alteration in the DNA code that marks the end of a gene. This deviation suggests that there's more to learn about the intriguing world of protists.
While studying the genome sequence of a protist from a freshwater pond at Oxford University Parks, intended to refine a DNA sequencing process for tiny DNA samples, like those from a single cell, Dr. McGowan and his team from both the Earlham Institute and the University of Oxford stumbled upon this genetic oddity.
The protist in question, Oligohymenophorea sp. PL0344, was identified as a new species showcasing an unusual pattern in its DNA translation into proteins. Reflecting on the unexpected discovery, Dr. McGowan commented, “It’s sheer luck we chose this protist to test our sequencing pipeline, and it just shows what’s out there, highlighting just how little we know about the genetics of protists.”
Protists are a diverse group, ranging from microscopic single-celled organisms like amoebas to larger multicellular entities like kelp. They defy a strict definition. Dr. McGowan elaborated, “The definition of a protist is loose –essentially it is any eukaryotic organism which is not an animal, plant, or fungus. “This is obviously very general, and that’s because protists are an extremely variable group.”
“Some are more closely related to animals, some more closely related to plants. There are hunters and prey, parasites and hosts, swimmers, and sitters, and there are those with varied diets while others photosynthesize. Basically, we can make very few generalizations.”
This protist, Oligohymenophorea sp. PL0344, is a type of ciliate. Visible under a microscope, ciliates are found in most watery environments. Known for their genetic code alterations, ciliates utilize one or more of the stop codons—TAA, TAG, and TGA—which typically signal the end of a gene in most organisms.
What's fascinating about the DNA of this particular protist is that only TGA serves as its stop codon. Dr. McGowan noted more TGA codons than usual in its DNA, which likely makes up for the lack of the other two codons. Contrary to typical organisms, in this protist, TAA translates to lysine and TAG to glutamic acid.
Commenting on this rare find, Dr. McGowan said, “This is extremely unusual. We’re not aware of any other case where these stop codons are linked to two different amino acids. It challenges some of the principles we believed about gene translation, [as] these two codons were perceived to be paired.”
The process of gene translation is like reading a blueprint. DNA provides instructions that need to be "read" and constructed into a molecule to have an effect. This translation begins at the DNA start codon and concludes at a stop codon.
Dr. McGowan emphasized the value of such discoveries, “Scientists attempt to engineer new genetic codes—but they are also out there in nature. There are fascinating things we can find, if we look for them. Or, in this case, when we are not looking for them.”
Concluding, this unexpected discovery underscores the importance of continued exploration in genetic research and its potential to challenge established beliefs about the world of genetics.
Read the original publication in PLOS Genetics.
The genome of a protist, analyzed by Dr. Jamie McGowan, a postdoctoral scientist at the Earlham Institute, has shown a unique alteration in the DNA code that marks the end of a gene. This deviation suggests that there's more to learn about the intriguing world of protists.
While studying the genome sequence of a protist from a freshwater pond at Oxford University Parks, intended to refine a DNA sequencing process for tiny DNA samples, like those from a single cell, Dr. McGowan and his team from both the Earlham Institute and the University of Oxford stumbled upon this genetic oddity.
The protist in question, Oligohymenophorea sp. PL0344, was identified as a new species showcasing an unusual pattern in its DNA translation into proteins. Reflecting on the unexpected discovery, Dr. McGowan commented, “It’s sheer luck we chose this protist to test our sequencing pipeline, and it just shows what’s out there, highlighting just how little we know about the genetics of protists.”
Protists are a diverse group, ranging from microscopic single-celled organisms like amoebas to larger multicellular entities like kelp. They defy a strict definition. Dr. McGowan elaborated, “The definition of a protist is loose –essentially it is any eukaryotic organism which is not an animal, plant, or fungus. “This is obviously very general, and that’s because protists are an extremely variable group.”
“Some are more closely related to animals, some more closely related to plants. There are hunters and prey, parasites and hosts, swimmers, and sitters, and there are those with varied diets while others photosynthesize. Basically, we can make very few generalizations.”
This protist, Oligohymenophorea sp. PL0344, is a type of ciliate. Visible under a microscope, ciliates are found in most watery environments. Known for their genetic code alterations, ciliates utilize one or more of the stop codons—TAA, TAG, and TGA—which typically signal the end of a gene in most organisms.
What's fascinating about the DNA of this particular protist is that only TGA serves as its stop codon. Dr. McGowan noted more TGA codons than usual in its DNA, which likely makes up for the lack of the other two codons. Contrary to typical organisms, in this protist, TAA translates to lysine and TAG to glutamic acid.
Commenting on this rare find, Dr. McGowan said, “This is extremely unusual. We’re not aware of any other case where these stop codons are linked to two different amino acids. It challenges some of the principles we believed about gene translation, [as] these two codons were perceived to be paired.”
The process of gene translation is like reading a blueprint. DNA provides instructions that need to be "read" and constructed into a molecule to have an effect. This translation begins at the DNA start codon and concludes at a stop codon.
Dr. McGowan emphasized the value of such discoveries, “Scientists attempt to engineer new genetic codes—but they are also out there in nature. There are fascinating things we can find, if we look for them. Or, in this case, when we are not looking for them.”
Concluding, this unexpected discovery underscores the importance of continued exploration in genetic research and its potential to challenge established beliefs about the world of genetics.
Read the original publication in PLOS Genetics.