TY - JOUR

T1 - Membrane Tubulation in Lipid Vesicles Triggered by the Local Application of Calcium Ions

AU - Doosti, Baharan Ali

AU - Pezeshkian, Weria

AU - Bruhn, Dennis S.

AU - Ipsen, John H.

AU - Khandelia, Himanshu

AU - Jeffries, Gavin D. M.

AU - Lobovidna, Tatsiana

PY - 2017/10/17

Y1 - 2017/10/17

N2 - Experimental and theoretical studies on ion-lipid interactions predict that binding of calcium ions to cell membranes leads to macroscopic mechanical effects and membrane remodeling. Herein, we provide experimental evidence that a point source of Ca2+ acting upon a negatively charged membrane generates spontaneous curvature and triggers the formation of tubular protrusions that point away from the ion source. This behavior is rationalized by strong binding of the divalent cations to the surface of the charged bilayer, which effectively neutralizes the surface charge density of outer leaflet of the bilayer. The mismatch in the surface charge density of the two leaflets leads to nonzero spontaneous curvature. We probe this mismatch through the use of molecular dynamics simulations and validate that calcium ion binding to a lipid membrane is sufficient to generate inward spontaneous curvature, bending the membrane. Additionally, we demonstrate that the formed tubular protrusions can be translated along the vesicle surface in a controlled manner by repositioning the site of localized Ca2+ exposure. The findings demonstrate lipid membrane remodeling in response to local chemical gradients and offer potential insights into the cell membrane behavior under conditions of varying calcium ion concentrations.

AB - Experimental and theoretical studies on ion-lipid interactions predict that binding of calcium ions to cell membranes leads to macroscopic mechanical effects and membrane remodeling. Herein, we provide experimental evidence that a point source of Ca2+ acting upon a negatively charged membrane generates spontaneous curvature and triggers the formation of tubular protrusions that point away from the ion source. This behavior is rationalized by strong binding of the divalent cations to the surface of the charged bilayer, which effectively neutralizes the surface charge density of outer leaflet of the bilayer. The mismatch in the surface charge density of the two leaflets leads to nonzero spontaneous curvature. We probe this mismatch through the use of molecular dynamics simulations and validate that calcium ion binding to a lipid membrane is sufficient to generate inward spontaneous curvature, bending the membrane. Additionally, we demonstrate that the formed tubular protrusions can be translated along the vesicle surface in a controlled manner by repositioning the site of localized Ca2+ exposure. The findings demonstrate lipid membrane remodeling in response to local chemical gradients and offer potential insights into the cell membrane behavior under conditions of varying calcium ion concentrations.

KW - COARSE-GRAINED MODEL

KW - PHOSPHATIDYLSERINE

KW - BILAYER

KW - DYNAMICS

KW - FUSION

KW - CURVATURE

KW - PHOSPHATIDYLCHOLINE

KW - INVAGINATIONS

KW - NANOTUBES

KW - MAGNESIUM

U2 - 10.1021/acs.langmuir.7b01461

DO - 10.1021/acs.langmuir.7b01461

M3 - Journal article

VL - 33

SP - 11010

EP - 11017

JO - Langmuir

JF - Langmuir

SN - 0743-7463

IS - 41

ER -