Metabolic complexity in the RNA world and implications for the origin of protein synthesis

Toby J. Gibson, Angus I. Lamond (Lead / Corresponding author)

    Research output: Contribution to journalArticlepeer-review

    50 Citations (Scopus)


    A model is presented for the evolution of metabolism and protein synthesis in a primitive, acellular RNA world. It has been argued previously that the ability to perform metabolic functions logically must have preceded the evolution of a message-dependent protein synthetic machinery and that considerable metabolic complexity was achieved by ribo-organisms (i.e., organisms in which both genome and enzymes are comprised of RNA). The model proposed here offers a mechanism to account for the gradual development of sophisticated metabolic activities by ribo-organisms and explains how such metabolic complexity would lead subsequently to the synthesis of genetically encoded polypeptides. RNA structures ancestral to modern ribosomes, here termed metabolosomes, are proposed to have functioned as organizing centers that coordinated, using base-pairing interactions, the order and nature of adaptor-mounted substrate/catalyst interactions in primitive metabolic pathways. In this way an ancient genetic code for metabolism is envisaged to have predated the specialized modern genetic code for protein synthesis. Thus, encoded amino acids initially would have been used, in conjunction with other encoded metabolites, as building blocks for biosynthetic pathways, a role that they retain in the metabolism of contemporary organisms. At a later stage the encoded amino acids would have been condensed together on similar RNA metabolosome structures to form the first genetically determined, and therefore biologically meaningful, polypeptides. On the basis of codon distributions in the modern genetic code it is argued that the first proteins to have been synthesized and used by ribo-organisms were predominantly hydrophobic and likely to have performed membrane-related functions (such as forming simple pore structures), activities essential for the evolution of membrane-enclosed cells.

    Original languageEnglish
    Pages (from-to)7-15
    Number of pages9
    JournalJournal of Molecular Evolution
    Issue number1
    Publication statusPublished - 1 Jan 1990


    • Genetic code for metabolism
    • Origin of protein synthesis
    • Precellular evolution
    • RNA adaptor-linked metabolites

    ASJC Scopus subject areas

    • Ecology, Evolution, Behavior and Systematics
    • Molecular Biology
    • Genetics


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