Alternate pleckstrin homology domain orientations regulate dynamin-catalyzed membrane fission
Autor: | Niharika Mehrotra, Justin S. Nichols, Rajesh Ramachandran |
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Jazyk: | angličtina |
Rok vydání: | 2014 |
Předmět: |
Models
Molecular endocrine system Molecular Sequence Data Static Electricity Gene Expression GTPase macromolecular substances Biology Endocytosis Protein Structure Secondary Membrane fission Escherichia coli Fluorescence Resonance Energy Transfer Humans Amino Acid Sequence Molecular Biology Dynamin I Dynamin Cell Membrane Cell Biology Articles Recombinant Proteins Cell biology Protein Structure Tertiary Pleckstrin homology domain Endocytic vesicle Membrane Membrane curvature Membrane Trafficking Liposomes Guanosine Triphosphate biological phenomena cell phenomena and immunity |
Zdroj: | Molecular Biology of the Cell |
ISSN: | 1939-4586 1059-1524 |
Popis: | The isolated dynamin PH domain is an assembly-independent sensor of membrane curvature but not a curvature generator. In full-length dynamin, the PH alternates between two different orientations on the membrane surface during the GTP hydrolysis cycle, causing dramatic fluctuations in the diameter of dynamin polymers. The self-assembling GTPase dynamin catalyzes endocytic vesicle scission via membrane insertion of its pleckstrin homology (PH) domain. However, the molecular mechanisms underlying PH domain–dependent membrane fission remain obscure. Membrane-curvature–sensing and membrane-curvature–generating properties have been attributed, but it remains to be seen whether the PH domain is involved in either process independent of dynamin self-assembly. Here, using multiple fluorescence spectroscopic and microscopic techniques, we demonstrate that the isolated PH domain does not act to bend membranes but instead senses high membrane curvature through hydrophobic insertion into the membrane bilayer. Furthermore, we use a complementary set of short- and long-distance Förster resonance energy transfer approaches to distinguish PH-domain orientation from proximity at the membrane surface in full-length dynamin. We reveal, in addition to the GTP-sensitive “hydrophobic mode,” the presence of an alternate, GTP-insensitive “electrostatic mode” of PH domain–membrane interactions that retains dynamin on the membrane surface during the GTP hydrolysis cycle. Stabilization of this alternate orientation produces dramatic variations in the morphology of membrane-bound dynamin spirals, indicating that the PH domain regulates membrane fission through the control of dynamin polymer dynamics. |
Databáze: | OpenAIRE |
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