# Conformational Dynamics of the Dynamin PH domain in Synaptic Vesicle Endocytosis

> **NIH NIH R21** · CASE WESTERN RESERVE UNIVERSITY · 2020 · $442,750

## Abstract

PROJECT SUMMARY
Synaptic transmission relies critically on the rapid uptake of emptied exocytic vesicle membrane remnants from
the presynaptic plasma membrane via the coupled and compensatory mechanisms of endocytosis catalyzed by
the large GTPase dynamin. Defects in synaptic vesicle recycling have been implicated in various neurological
disorders including Epilepsy, Down’s syndrome, Alzheimer’s, Parkinson’s and Huntington’s diseases. Emerging
evidence indicates that in addition to dynamin’s better-characterized helical polymerization and
mechanoenzymatic membrane constriction activities, a third distinct activity involving the alternative tilting or
orientation of its pleckstrin homology (PH) domain at the membrane surface governs synaptic vesicle scission.
The mechanisms remain largely uncharacterized. Disease-causing mutations in dynamin, which precipitate
centronuclear myopathy (CNM) and Charcot-Marie-Tooth (CMT) disease, map largely to the PH domain or to its
various intermolecular interfaces. Although this underscores the importance of the PH domain in dynamin
function, it is unclear how these mutations specifically influence PH domain interactions or conformational
behavior at the membrane surface. It is our long-term goal to understand the various molecular mechanisms at
play in dynamin-mediated endocytic vesicle scission. In this proposal, we seek to address several unknown or
unresolved fundamental issues concerning the role of the PH domain in dynamin function, both in solution and
on membranes. These include: 1) the regulatory mechanisms and conformational rearrangements that underlie
the transition of dynamin from stable, self-limited, cytosolic tetramers to dynamic, self-assembled, membrane-
bound helical polymers, 2) the conformational coupling of dynamin PH domain-membrane insertion and alternate
orientations to helical self-assembly and the coordination of assembly-dependent GTPase activity, and 3) the
molecular nature and structural basis of alternate PH domain orientations on the membrane surface. To address
these, we will use a powerful combination of multiple independent fluorescence spectroscopic techniques
including Förster resonance energy transfer (FRET), fluorescence lifetime analysis, quenching and stopped-flow
kinetic measurements, coupled to sophisticated NMR spectroscopic measurements of the dynamin PH domain
on various biomimetic lipid templates. Successful outcomes of this research will provide (i) a fundamentally
improved understanding of the mechanisms of dynamin function that underlie rapid synaptic vesicle scission,
and (ii) a molecular foundation for the design of drugs and therapeutics that can beneficially modulate synaptic
vesicle endocytosis under various disease states.

## Key facts

- **NIH application ID:** 10057144
- **Project number:** 1R21NS115071-01A1
- **Recipient organization:** CASE WESTERN RESERVE UNIVERSITY
- **Principal Investigator:** Rajesh Ramachandran
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $442,750
- **Award type:** 1
- **Project period:** 2020-06-01 → 2022-11-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10057144

## Citation

> US National Institutes of Health, RePORTER application 10057144, Conformational Dynamics of the Dynamin PH domain in Synaptic Vesicle Endocytosis (1R21NS115071-01A1). Retrieved via AI Analytics 2026-06-01 from https://api.ai-analytics.org/grant/nih/10057144. Licensed CC0.

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