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08/22/2025 08:02

New dynamics in endocytosis: proteins build flexible networks for transporting molecules

Julia Kirchner Presse- und Öffentlichkeitsarbeit
Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP)

    A research team has gained new insights into the molecular processes of clathrin-mediated endocytosis – the central process by which cells take up nutrients, messenger substances and receptors. The study by junior research group leader Dr. Sigrid Milles, Andromachi Papagiannoula and Dr. Ida Marie Vedel from the Leibniz-Forschungsinstitut für Molekulare Pharmakologie in Berlin focuses on the molecular interactions between the EH domains of the endocytosis protein Eps15 and an intrinsically disordered fragment of Dab2. The results were recently published in Nature Communications.

    Using high-resolution NMR spectroscopy, the researchers were able to show that the EH domains of Eps15 bind much more versatilely than previously assumed. Instead of recognizing only one classic binding motif, they also attach promiscuously to other phenylalanine-containing sequences. Surprisingly, Eps15 not only binds to its partner Dab2, but also to its own intrinsically disordered segment (Eps15IDR). This leads to a kind of self-inhibition, but at the same time ensures that Eps15 can form liquid-like condensates (liquid-liquid phase separation). Dab2320-495 alone cannot form droplets, but is recruited into the Eps15 condensates without significantly disrupting their formation.

    An exciting finding of the study is that both Eps15IDR and Dab2320-495 can bind to the combined domain region EH123 at the same time, even though they compete for the same binding pockets. This interaction creates a very dynamic, flexible network. ‘The fact that proteins that compete with the interaction between EH domains and Eps15IDR can penetrate the Eps15 condensates is astonishing and was not directly expected, but it means that Eps15 is probably capable of recruiting many other proteins to the membrane,’ says Sigrid Milles.

    Weak bonds as a prerequisite for cell flexibility

    The results show that weakness is a strength here: the bonds between the proteins are not rigid, but deliberately loose. Only in this way can they quickly detach and reattach – a decisive factor for the high dynamics of endocytosis.

    The researchers led by Sigrid Milles have thus provided a new model for how molecular versatility and self-organization ensure that vital transport processes in the cell run smoothly and flexibly. In the long term, this knowledge could help to better understand diseases in which endocytosis is disrupted, such as cancer or neurodegenerative diseases.


    Contact for scientific information:

    Dr. Sigrid Milles
    Junior group leader – Integrated Structural Dynamics
    Leibniz-Forschungsinstitut für Molekulare Pharmakologie
    Tel: +49 30 94793 244
    Email: milles@fmp-berlin.de


    Original publication:

    Papagiannoula, A., Vedel, I.M., Motzny, K. et al. Promiscuous and multivalent interactions between Eps15 and partner protein Dab2 generate a complex interaction network. Nat Commun 16, 7783 (2025). https://doi.org/10.1038/s41467-025-63090-1


    Images

    Junior group leader Dr. Sigrid Milles
    Junior group leader Dr. Sigrid Milles
    Source: Silke Osswald
    Copyright: FMP/Silke Osswald

    The weak multivalent interaction network of the two IDRs with EH123 likely contributes to co-phase separation of Eps15 and Dab2320–495. Eps15:Dab2 interactions = turquoise shading, Eps15:Eps15 interactions = pink shading
    The weak multivalent interaction network of the two IDRs with EH123 likely contributes to co-phase s ...

    Copyright: FMP/Barth van Rossum


    Criteria of this press release:
    Journalists, Scientists and scholars, Students
    Biology
    transregional, national
    Research results, Scientific Publications
    English


     

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