Open Access

Exploring the binding dynamics of BAR proteins

  • Doron Kabaso1Email author,
  • Ekaterina Gongadze2,
  • Jernej Jorgačevski3, 4,
  • Marko Kreft3, 4,
  • Ursula Van Rienen2,
  • Robert Zorec3, 4 and
  • Aleš Iglič1
Cellular & Molecular Biology LettersAn International Journal201116:13

https://doi.org/10.2478/s11658-011-0013-0

Received: 29 April 2010

Accepted: 11 May 2011

Published: 25 May 2011

Abstract

We used a continuum model based on the Helfrich free energy to investigate the binding dynamics of a lipid bilayer to a BAR domain surface of a crescent-like shape of positive (e.g. I-BAR shape) or negative (e.g. F-BAR shape) intrinsic curvature. According to structural data, it has been suggested that negatively charged membrane lipids are bound to positively charged amino acids at the binding interface of BAR proteins, contributing a negative binding energy to the system free energy. In addition, the cone-like shape of negatively charged lipids on the inner side of a cell membrane might contribute a positive intrinsic curvature, facilitating the initial bending towards the crescent-like shape of the BAR domain. In the present study, we hypothesize that in the limit of a rigid BAR domain shape, the negative binding energy and the coupling between the intrinsic curvature of negatively charged lipids and the membrane curvature drive the bending of the membrane. To estimate the binding energy, the electric potential at the charged surface of a BAR domain was calculated using the Langevin-Bikerman equation. Results of numerical simulations reveal that the binding energy is important for the initial instability (i.e. bending of a membrane), while the coupling between the intrinsic shapes of lipids and membrane curvature could be crucial for the curvature-dependent aggregation of negatively charged lipids near the surface of the BAR domain. In the discussion, we suggest novel experiments using patch clamp techniques to analyze the binding dynamics of BAR proteins, as well as the possible role of BAR proteins in the fusion pore stability of exovesicles.

Key words

BAR proteins Binding dynamics Patch clamp Charged lipids Intrinsic shape

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