Bioinformatics Advance Access published online on May 8, 2007
Bioinformatics, doi:10.1093/bioinformatics/btm250
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Persistent voids: a new structural metric for membrane fusion
1Medical Scientist Training Program, 2Department of Chemistry, 4Department of Computer Science, Stanford University, Stanford CA 94305, and 3Department of Computer Science, Dartmouth College, Hanover NH 03755.
*To whom correspondence should be addressed. Vijay S. Pande, E-mail: pande{at}stanford.edu
| Abstract |
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Motivation: Membrane fusion constitutes a key stage in cellular processes such as synaptic neurotransmission and infection by enveloped viruses. Current experimental assays for fusion have thus far been unable to resolve early fusion events in structural detail. We have previously used molecular dynamics simulations to develop mechanistic models of fusion by small lipid vesicles. Here, we introduce a novel structural measurement of vesicle topology and fusion geometry: persistent voids.
Results: Persistent voids calculations enable systematic measurement of structural changes in vesicle fusion by assessing fusion stalk widths. They also constitute a generally applicable technique for assessing lipid topological change. We use persistent voids to compute dynamic relationships between hemifusion neck widening and formation of a full fusion pore in our simulation data. We predict that a tightly coordinated process of hemifusion neck expansion and pore formation is responsible for the rapid vesicle fusion mechanism, while isolated enlargement of the hemifusion diaphragm leads to the formation of a metastable hemifused intermediate. These findings suggest that rapid fusion between small vesicles proceeds via a small hemifusion diaphragm rather than a full-expanded one.
Availability: Software available upon request pending public release.
Associate Editor: Prof. Anna Tramontano
Received on February 10, 2007; revised on April 13, 2007; accepted on May 2, 2007