This Article Full Text Full Text (PDF) All Versions of this Article: biophysj.105.071092v1 90/3/915    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Katsov, K. Articles by Schick, M. Search for Related Content PubMed PubMed Citation Articles by Katsov, K. Articles by Schick, M.

Field Theoretic Study of Bilayer Membrane Fusion: II. Mechanism of a Stalk-Hole Complex

K. Katsov ^*, M. Müller  and M. Schick 

^* Materials Research Laboratory, University of California, Santa Barbara, California; Institut für Theoretische Physik, Göttingen, Germany; and Department of Physics, University of Washington, Seattle, Washington

Correspondence: Address reprint requests to M. Schick, Tel.: 206-543-9948; E-mail: schick{at}phys.washington.edu.

We use self-consistent field theory to determine structural and energetic properties of intermediates and transition states involved in bilayer membrane fusion. In particular, we extend our original calculations from those of the standard hemifusion mechanism, which was studied in detail in the first article of this series, to consider a possible alternative to it. This mechanism involves non-axial stalk expansion, in contrast to the axially symmetric evolution postulated in the classical mechanism. Elongation of the initial stalk facilitates the nucleation of holes and leads to destabilization of the fusing membranes via the formation of a stalk-hole complex. We study properties of this complex in detail, and show how transient leakage during fusion, previously predicted and recently observed in experiment, should vary with lipid architecture and tension. We also show that the barrier to fusion in the alternative mechanism is lower than that of the standard mechanism by a few k_BT over most of the relevant region of system parameters, so that this alternative mechanism is a viable alternative to the standard pathway. We emphasize that any mechanism, such as this alternative one, which affects, even modestly, the line tension of a hole in a membrane, affects greatly the ability of that membrane to undergo fusion.

This article has been cited by other articles:

				A. Arkhipov, Y. Yin, and K. Schulten Four-Scale Description of Membrane Sculpting by BAR Domains Biophys. J., September 15, 2008; 95(6): 2806 - 2821. [Abstract] [Full Text] [PDF]

				J. Y. Lee and M. Schick Calculation of Free Energy Barriers to the Fusion of Small Vesicles Biophys. J., March 1, 2008; 94(5): 1699 - 1706. [Abstract] [Full Text] [PDF]

				V. Knecht and S.-J. Marrink Molecular Dynamics Simulations of Lipid Vesicle Fusion in Atomic Detail Biophys. J., June 15, 2007; 92(12): 4254 - 4261. [Abstract] [Full Text] [PDF]

				J. Y. Lee and M. Schick Field Theoretic Study of Bilayer Membrane Fusion III: Membranes with Leaves of Different Composition Biophys. J., June 1, 2007; 92(11): 3938 - 3948. [Abstract] [Full Text] [PDF]