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Why do c-type cytochromes exist?

P M Wood

    FEBS Letters
    |December 12, 1983
    PubMed

    Insights

    C-type cytochromes likely evolved in bacterial periplasms to prevent heme loss. This evolutionary origin explains their structure and function in electron transport chains, even in eukaryotes.

    Area of Science:

    • Biochemistry
    • Evolutionary Biology
    • Microbiology

    Background:

    • C-type cytochromes are crucial proteins involved in electron transport.
    • Their evolutionary origins and precise functions in various organisms are not fully understood.
    • The role of covalent heme-protein linkages in cytochrome stability is a key area of interest.

    Purpose of the Study:

    • To propose a hypothesis for the evolutionary origin of c-type cytochromes.
    • To explain the retention of covalent heme-protein bonds throughout evolution.
    • To provide a framework for understanding electron transport chains with novel components.

    Main Methods:

    • Hypothetical evolutionary analysis of c-type cytochrome structure and location.
    • Comparative analysis of cytochrome localization in bacterial, eukaryotic, and cyanobacterial systems.
    • Consideration of the structural and functional implications of covalent heme attachment.

    Main Results:

    • Hypothesizes that c-type cytochromes originated in the bacterial periplasmic space or membrane.
    • Suggests covalent heme-protein bonds evolved to prevent heme loss in these external locations.
    • Proposes that these bonds were retained for structural integrity during subsequent evolutionary internalization.

    Conclusions:

    • The periplasmic origin hypothesis provides a plausible explanation for the conserved structure of c-type cytochromes.
    • This evolutionary perspective can aid in deciphering complex and unconventional electron transport pathways.
    • Further investigation into apparent exceptions is warranted to refine the understanding of cytochrome evolution.

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