Grazing-Angle Neutron Diffraction Study of the Water Distribution in Membrane Hemifusion: From the Lamellar to Rhombohedral Phase

Qian, Shuo; Rai, Durgesh K.

doi:10.1021/acs.jpclett.8b01602

Title: Grazing-Angle Neutron Diffraction Study of the Water Distribution in Membrane Hemifusion: From the Lamellar to Rhombohedral Phase

Abstract

The water distribution between lipid bilayers is important in understanding the role of the hydration force at different steps of the membrane fusion pathway. Here in this study, we used grazing-angle neutron diffraction to map out the water distribution in lipid bilayers transiting from a lamellar structure to the hemifusion “stalk” structure in a rhombohedral phase. Under osmotic pressure exerted by different levels of relative humidity, the lipid membrane sample was maintained in equilibrium at different lattices suitable for neutron diffraction. The D₂O used to hydrate the lipid membrane sample stood out from the lipid in the reconstructed structure because of its much higher coherent neutron scattering length density. The density map indicates that water dissociated from the headgroup in the lamellar phase. In the rhombohedral phase, water was significantly reduced and was squeezed into pockets around the stalk. This study complements earlier structural studies by grazing-angle X-ray diffraction, which is sensitive to only the parts of the structure with high electron density (such as phosphors). The experiment also demonstrated that the recently developed time-of-flight small-angle neutron scattering beamline at the Spallation Neutron Source is suitable for grazing-angle neutron diffraction to provide the structures of large unit cells on themore »« less

Authors:

^[1]; Rai, Durgesh K. ^[2]

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Neutron Scattering Division, and Center for Structural Molecular Biology
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Neutron Scattering Division

Publication Date:: Thu Sep 20 00:00:00 EDT 2018

Research Org.:: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:: USDOE Office of Science (SC), Biological and Environmental Research (BER)

OSTI Identifier:: 1471910

Grant/Contract Number:: AC05-00OR22725

Resource Type:: Accepted Manuscript

Journal Name:: Journal of Physical Chemistry Letters

Additional Journal Information:: Journal Volume: 9; Journal ID: ISSN 1948-7185

Publisher:: American Chemical Society

Country of Publication:: United States

Language:: English

Subject:: 59 BASIC BIOLOGICAL SCIENCES; membrane fusion; hydration force; water; grazing-angle neutron diffraction

Citation Formats


                    Qian, Shuo, and Rai, Durgesh K. Grazing-Angle Neutron Diffraction Study of the Water Distribution in Membrane Hemifusion: From the Lamellar to Rhombohedral Phase.  United States: N. p., 2018. 
Web.  doi:10.1021/acs.jpclett.8b01602.

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                    Qian, Shuo, & Rai, Durgesh K. Grazing-Angle Neutron Diffraction Study of the Water Distribution in Membrane Hemifusion: From the Lamellar to Rhombohedral Phase.  United States.  https://doi.org/10.1021/acs.jpclett.8b01602

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                    Qian, Shuo, and Rai, Durgesh K. Thu .  
"Grazing-Angle Neutron Diffraction Study of the Water Distribution in Membrane Hemifusion: From the Lamellar to Rhombohedral Phase".  United States.  https://doi.org/10.1021/acs.jpclett.8b01602.  https://www.osti.gov/servlets/purl/1471910.

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@article{osti_1471910,

  title        = {Grazing-Angle Neutron Diffraction Study of the Water Distribution in Membrane Hemifusion: From the Lamellar to Rhombohedral Phase},

  author       = {Qian, Shuo and Rai, Durgesh K.},

  abstractNote = {The water distribution between lipid bilayers is important in understanding the role of the hydration force at different steps of the membrane fusion pathway. Here in this study, we used grazing-angle neutron diffraction to map out the water distribution in lipid bilayers transiting from a lamellar structure to the hemifusion “stalk” structure in a rhombohedral phase. Under osmotic pressure exerted by different levels of relative humidity, the lipid membrane sample was maintained in equilibrium at different lattices suitable for neutron diffraction. The D2O used to hydrate the lipid membrane sample stood out from the lipid in the reconstructed structure because of its much higher coherent neutron scattering length density. The density map indicates that water dissociated from the headgroup in the lamellar phase. In the rhombohedral phase, water was significantly reduced and was squeezed into pockets around the stalk. This study complements earlier structural studies by grazing-angle X-ray diffraction, which is sensitive to only the parts of the structure with high electron density (such as phosphors). The experiment also demonstrated that the recently developed time-of-flight small-angle neutron scattering beamline at the Spallation Neutron Source is suitable for grazing-angle neutron diffraction to provide the structures of large unit cells on the order of a few nanometers, such as biomembrane structures.},

  doi          = {10.1021/acs.jpclett.8b01602},

  journal      = {Journal of Physical Chemistry Letters},

  number       = ,

  volume       = 9,

  place        = {United States},

  year         = {Thu Sep 20 00:00:00 EDT 2018},

  month        = {Thu Sep 20 00:00:00 EDT 2018}

}

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https://doi.org/10.1021/acs.jpclett.8b01602

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Cited by: 6 works

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Figures / Tables:

Figure 1: Grazing-angle neutron diffraction pattern mapped to 2-dimensional $q$_z-$q$_r space. (A) RH 85%, (B) RH 82%, (C) RH 57%, RH, (D) 50%. The color scales are in arbitrary units.

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