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Uncovering the Ancient Source of Immune System Variety

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In a new study, Vladimir Kapitonov and Jerzy Jurka have found that RAG1 is similar to transposases encoded by transposons (jumping genes that encode transposases necessary for their mobility) found in both terrestrial and marine organisms: the fruit fly and malaria-carrying African mosquito and the sea urchin and hydra... To find more statistical evidence of a relationship, Kapitonov and Jurka searched for more Transib proteins... They found a diverse family of Transib transposases in various animals, including silkworm, red flour beetle, dog hookworm, soybean rust, and hydra... The authors also found that plants and vertebrates appear not to contain Transib proteins... With the new proteins in tow, Kapitonov and Jurka found that a 600-amino-acid region of RAG1 was statistically similar to Transib transposases... However, Kapitonov and Jurka could not find any RAG2-like proteins encoded by Transib transposons... This theory was previously up for debate, as it was possible that RAG1 and RAG2 could have independently evolved to function like transposons... But the authors suggest that “these arguments can now be put to rest,” as it appears RAG1 evolved from a transposon currently found in flies and other organisms... Future experiments on how Transib transposons work may allow further understanding into how RAG1 and RAG2 evolved and how they function in vertebrates.

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A gene involved in V(D)J recombination—which allows immune cells to recognize an unlimited number of antigens by reshuffling immune receptor gene segments—evolved from an ancient gene-transposing enzyme
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pbio-0030212-g001: A gene involved in V(D)J recombination—which allows immune cells to recognize an unlimited number of antigens by reshuffling immune receptor gene segments—evolved from an ancient gene-transposing enzyme

Mentions: With the new proteins in tow, Kapitonov and Jurka found that a 600-amino-acid region of RAG1 was statistically similar to Transib transposases. This 600-amino-acid region of RAG1 forms the core region that mediates V(D)J recombination. Three important amino acids, which underlie RAG1's ability to recombine gene segments, are also conserved in Transib transposases. Furthermore, RAG1 and RAG2 are known to recombine V, D, and J segments by binding to specific signals in these genes (called recombination signal sequences), which appear to have been derived from the ends of Transib transposons. It was previously thought that both RAG1 and RAG2 likely evolved from two proteins encoded by the same transposon. However, Kapitonov and Jurka could not find any RAG2-like proteins encoded by Transib transposons. The authors therefore suggest that RAG2 appeared later in jawed vertebrates as a necessary component for the evolution of V(D)J recombination.


Uncovering the Ancient Source of Immune System Variety
A gene involved in V(D)J recombination—which allows immune cells to recognize an unlimited number of antigens by reshuffling immune receptor gene segments—evolved from an ancient gene-transposing enzyme
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC1131884&req=5

pbio-0030212-g001: A gene involved in V(D)J recombination—which allows immune cells to recognize an unlimited number of antigens by reshuffling immune receptor gene segments—evolved from an ancient gene-transposing enzyme
Mentions: With the new proteins in tow, Kapitonov and Jurka found that a 600-amino-acid region of RAG1 was statistically similar to Transib transposases. This 600-amino-acid region of RAG1 forms the core region that mediates V(D)J recombination. Three important amino acids, which underlie RAG1's ability to recombine gene segments, are also conserved in Transib transposases. Furthermore, RAG1 and RAG2 are known to recombine V, D, and J segments by binding to specific signals in these genes (called recombination signal sequences), which appear to have been derived from the ends of Transib transposons. It was previously thought that both RAG1 and RAG2 likely evolved from two proteins encoded by the same transposon. However, Kapitonov and Jurka could not find any RAG2-like proteins encoded by Transib transposons. The authors therefore suggest that RAG2 appeared later in jawed vertebrates as a necessary component for the evolution of V(D)J recombination.

View Article: PubMed Central

AUTOMATICALLY GENERATED EXCERPT
Please rate it.

In a new study, Vladimir Kapitonov and Jerzy Jurka have found that RAG1 is similar to transposases encoded by transposons (jumping genes that encode transposases necessary for their mobility) found in both terrestrial and marine organisms: the fruit fly and malaria-carrying African mosquito and the sea urchin and hydra... To find more statistical evidence of a relationship, Kapitonov and Jurka searched for more Transib proteins... They found a diverse family of Transib transposases in various animals, including silkworm, red flour beetle, dog hookworm, soybean rust, and hydra... The authors also found that plants and vertebrates appear not to contain Transib proteins... With the new proteins in tow, Kapitonov and Jurka found that a 600-amino-acid region of RAG1 was statistically similar to Transib transposases... However, Kapitonov and Jurka could not find any RAG2-like proteins encoded by Transib transposons... This theory was previously up for debate, as it was possible that RAG1 and RAG2 could have independently evolved to function like transposons... But the authors suggest that “these arguments can now be put to rest,” as it appears RAG1 evolved from a transposon currently found in flies and other organisms... Future experiments on how Transib transposons work may allow further understanding into how RAG1 and RAG2 evolved and how they function in vertebrates.

No MeSH data available.