An ancient enzyme drives diversification of immune receptors in lampreys, and resembles an enzyme with a similar function in mammals, according to a report published online in Nature Immunology.
Zeev Pancer and colleagues used computational analyses - 'genomic mining' - to look for molecular signatures in the lamprey genome. Clues to how lampreys diversify their antigen receptors, allowing them to combat any array of potential microbial threats, came from their identification of hundreds of short gene segments that encode bits of the antigen receptors. The authors also discovered evidence that these pieces can combine in almost an infinite array, thereby explaining how a diverse repertoire of receptors can be made.
The surprise the authors found in the lamprey genomic sequence was that these fish encode two enzymes similar to an enzyme called AID, which is essential for the production of different types of antibodies in mammals. In fact, further experiments performed in test tubes showed the lamprey enzymes can mutate target genes much like the mammalian AID enzyme. The new work suggests the ability to diversify antigen receptors occurred much earlier in evolution then previously thought and hence is an 'ancient adaptation'.
Zeev Pancer (University of Maryland Biotechnology Institute, Baltimore, MD, USA)
Additional contact for comment on paper:
David Schatz (Yale University School of Medicine, New Haven, CT, USA)
Abstract available online.
(C) Nature Immunology press release.
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