Protective hinge in insulin opens to enable its receptor engagement

John G. Menting, Yanwu Yang, Shu Jin Chan, Nelson B. Phillips, Brian J. Smith, Jonathan Whittaker, Nalinda P. Wickramasinghe, Linda J. Whittaker, Vijay Pandyarajan, Zhu Li Wan, Satya P. Yadav, Julie M. Carroll, Natalie Strokes, Charles T. Roberts, Faramarz Ismail-Beigi, Wieslawa Milewski, Donald F. Steiner, Virander S. Chauhan, Colin W. Ward, Michael A. WeissMichael C. Lawrence

    Research output: Contribution to journalArticle

    79 Scopus citations

    Abstract

    Insulin provides a classical model of a globular protein, yet how the hormone changes conformation to engage its receptor has long been enigmatic. Interest has focused on the C-terminal B-chain segment, critical for protective self-assembly in β cells and receptor binding at target tissues. Insight may be obtained from truncated "microreceptors" that reconstitute the primary hormone-binding site (α-subunit domains L1 and αCT). We demonstrate that, on microreceptor binding, this segment undergoes concerted hinge-like rotation at its B20-B23 β-turn, coupling reorientation of PheB24 to a 60° rotation of the B25-B28 β-strand away from the hormone core to lie antiparallel to the receptor's L1-β2 sheet. Opening of this hinge enables conserved nonpolar side chains (Ile A2, ValA3, ValB12, PheB24, and PheB25) to engage the receptor. Restraining the hinge by nonstandard mutagenesis preserves native folding but blocks receptor binding, whereas its engineered opening maintains activity at the price of protein instability and nonnative aggregation. Our findings rationalize properties of clinical mutations in the insulin family and provide a previously unidentified foundation for designing therapeutic analogs. We envisage that a switch between free and receptor-bound conformations of insulin evolved as a solution to conflicting structural determinants of biosynthesis and function.

    Original languageEnglish (US)
    Pages (from-to)E3395-E3404
    JournalProceedings of the National Academy of Sciences of the United States of America
    Volume111
    Issue number33
    DOIs
    StatePublished - Aug 19 2014

    Keywords

    • Diabetes mellitus
    • Metabolism
    • Protein structure
    • Receptor tyrosine kinase
    • Signal transduction

    ASJC Scopus subject areas

    • General

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  • Cite this

    Menting, J. G., Yang, Y., Chan, S. J., Phillips, N. B., Smith, B. J., Whittaker, J., Wickramasinghe, N. P., Whittaker, L. J., Pandyarajan, V., Wan, Z. L., Yadav, S. P., Carroll, J. M., Strokes, N., Roberts, C. T., Ismail-Beigi, F., Milewski, W., Steiner, D. F., Chauhan, V. S., Ward, C. W., ... Lawrence, M. C. (2014). Protective hinge in insulin opens to enable its receptor engagement. Proceedings of the National Academy of Sciences of the United States of America, 111(33), E3395-E3404. https://doi.org/10.1073/pnas.1412897111