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Domain stealing by receptors in a protein transport complex

Joanne M Hulett, Peter Walsh, Trevor Lithgow

    Molecular Biology and Evolution
    |June 26, 2007
    PubMed

    Insights

    Mitochondrial proteins Tom20 and Tom22 in yeast show domain stealing, where one gains a domain lost by the other. This reveals their cooperative function in protein import for mitochondrial biogenesis.

    Area of Science:

    • Cell Biology
    • Evolutionary Biology
    • Biochemistry

    Background:

    • Mitochondria are vital organelles in eukaryotic cells, crucial for cellular energy production and homeostasis.
    • The import of nuclear-encoded proteins into mitochondria is a complex process essential for mitochondrial function and biogenesis.
    • Tom20 and Tom22 are key outer mitochondrial membrane receptors involved in recognizing and binding precursor proteins destined for import.

    Discussion:

    • A comparative sequence analysis of Tom20 and Tom22 in Saccharomyces cerevisiae and Saccharomyces castellii revealed a rare evolutionary event termed 'domain stealing'.
    • In Saccharomyces castellii, the Tom22 protein has lost an acidic domain, while the Tom20 protein has acquired it.
    • This finding suggests that Tom20 and Tom22 function as a single, composite receptor, rather than independent entities.

    Key Insights:

    • The observed domain stealing provides direct evidence for the co-evolution and functional interdependence of Tom20 and Tom22.
    • This evolutionary mechanism highlights the plasticity of protein domains and their rearrangement during evolution.
    • The study demonstrates how analyzing sequence variations can illuminate the functional relationships between proteins.

    Outlook:

    • Further investigation into the structural and functional consequences of this domain rearrangement can deepen our understanding of mitochondrial protein import.
    • Exploring similar domain stealing events in other protein families may reveal broader evolutionary principles.
    • This research contributes to the ongoing effort to map the intricate pathways of mitochondrial biogenesis and evolution.

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