Dynamin GTPase regulation is altered by PH domain mutations found in centronuclear myopathy patients

Authors

  • Jon A Kenniston,

    Corresponding author
    1. Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
    • Corresponding authors. Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, 806-809C Stellar-Chance Laboratories, 422 Curie Boulevard, Philadelphia, PA 19104-6059, USA. Tel.: +1 215 898 3411; Fax: +1 215 573 4764; E-mail: jkennist@mail.med.upenn.edu or Tel.: +1 215 898 3072; Fax: +1 215 573 4764; E-mail: mlemmon@mail.med.upenn.edu

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  • Mark A Lemmon

    Corresponding author
    1. Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
    • Corresponding authors. Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, 806-809C Stellar-Chance Laboratories, 422 Curie Boulevard, Philadelphia, PA 19104-6059, USA. Tel.: +1 215 898 3411; Fax: +1 215 573 4764; E-mail: jkennist@mail.med.upenn.edu or Tel.: +1 215 898 3072; Fax: +1 215 573 4764; E-mail: mlemmon@mail.med.upenn.edu

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Abstract

The large GTPase dynamin has an important membrane scission function in receptor-mediated endocytosis and other cellular processes. Self-assembly on phosphoinositide-containing membranes stimulates dynamin GTPase activity, which is crucial for its function. Although the pleckstrin-homology (PH) domain is known to mediate phosphoinositide binding by dynamin, it remains unclear how this promotes activation. Here, we describe studies of dynamin PH domain mutations found in centronuclear myopathy (CNM) that increase dynamin's GTPase activity without altering phosphoinositide binding. CNM mutations in the PH domain C-terminal α-helix appear to cause conformational changes in dynamin that alter control of the GTP hydrolysis cycle. These mutations either ‘sensitize’ dynamin to lipid stimulation or elevate basal GTPase rates by promoting self-assembly and thus rendering dynamin no longer lipid responsive. We also describe a low-resolution structure of dimeric dynamin from small-angle X-ray scattering that reveals conformational changes induced by CNM mutations, and defines requirements for domain rearrangement upon dynamin self-assembly at membrane surfaces. Our data suggest that changes in the PH domain may couple lipid binding to dynamin GTPase activation at sites of vesicle invagination.

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