An Ancient Immune Puzzle: How Primitive Fish Rewrite the Rules of Antigen Presentation
A study of holostean fish—gars and bowfins—has uncovered unique evolutionary novelties in a core component of the vertebrate immune system. Researchers focused on PSMB8, a key part of the immunoproteasome that chops up proteins into peptides for presentation by MHC class I molecules. They identified two distinct PSMB8 types (S and K) in these ancient fish lineages that are not found in other vertebrates. These novel types likely alter the biochemical properties of the enzyme’s binding pocket, potentially enabling the presentation of a different repertoire of antigenic peptides. This finding suggests that the fundamental machinery for alerting the adaptive immune system to infection has undergone more diverse and lineage-specific evolution than previously appreciated.
Why it might matter to you:
This work reveals deep evolutionary flexibility in a fundamental immune pathway you study in the context of host-pathogen interactions and vaccine design. Understanding how the antigen-processing machinery can diverge to present novel peptides could inform strategies for overcoming immune evasion by pathogens or for engineering more effective vaccine antigens. The findings highlight that even conserved systems like MHC-I presentation harbor untapped variation, which may be relevant for tailoring immunotherapies or understanding transplantation compatibility.
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