The cotranslational contacts between ribosome-bound nascent polypeptides and the subunits of the hetero-oligomeric chaperonin TRiC probed by photocross-linking

Stephanie A. Etchells, Anne S. Meyer, Alice Y. Yam, Anne Roobol, Yiwei Miao, Yuanlong Shao, Martin J. Carden, William R. Skach, Judith Frydman, Arthur E. Johnson

    Research output: Contribution to journalArticlepeer-review

    34 Scopus citations

    Abstract

    The hetero-oligomeric eukaryotic chaperonin TRiC (TCP-1-ring complex, also called CCT) interacts cotranslationally with a diverse subset of newly synthesized proteins, including actin, tubulin, and luciferase, and facilitates their correct folding. A photocross-linking approach has been used to map the contacts between individual chaperonin subunits and ribosome-bound nascent chains of increasing length. Whereas a cryo-EM study suggests that chemically denatured actin interacts with only two TRiC subunits (δ and either β or ε), actin and luciferase chains photocross-link to at least six TRiC subunits (α, β, δ, ε, ξ, and θ) at different stages of translation. Furthermore, the photocross-linking of actin, but not luciferase, nascent chains to TRiC sub-units ζ and θ was length-dependent. In addition, a single photoreactive probe incorporated at a unique site in actin nascent chains of different lengths reacted covalently with multiple TRiC subunits, thereby indicating that the nascent chain samples the polypeptide binding sites of different subunits. We conclude that elongating actin and luciferase nascent chains contact multiple TRiC subunits upon emerging from the ribosome, and that the TRiC subunits contacted by nascent actin change as it elongates and starts to fold.

    Original languageEnglish (US)
    Pages (from-to)28118-28126
    Number of pages9
    JournalJournal of Biological Chemistry
    Volume280
    Issue number30
    DOIs
    StatePublished - Jul 29 2005

    ASJC Scopus subject areas

    • Biochemistry
    • Molecular Biology
    • Cell Biology

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