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Title: Regulation of the Electric Charge in Phosphatidic Acid Domains

Abstract

Although a minor component of the lipidome, phosphatidic acid (PA) plays a crucial role in nearly all signaling pathways involving cell membranes, in part because of its variable electrical charge in response to environmental conditions. To investigate how charge is regulated in domains of PA, we applied surface-sensitive X-ray reflectivity and fluorescence near-totalreflection techniques to determine the binding of divalent ions (Ca2+ at various pH values) to 1,2-dimyristoyl-sn-glycero-3-phosphate (DMPA) and to the simpler lipid dihexadecyl phosphate (DHDP) spread as monolayers at the air/water interface. We found that the protonation state of PA is controlled not only by the pKa and local pH but also by the strong affinity to PA driven by electrostatic correlations from divalent ions and the cooperative effect of the two dissociable protons, which dramatically enhance the surface charge. A precise theoretical model is presented providing a general framework to predict the protonation state of PA. Implications for recent experiments on charge regulation by hydrogen bonding and the role of pH in PA signaling are discussed in detail.

Authors:
; ; ;
Publication Date:
Research Org.:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1047712
Report Number(s):
IS-J 7725
DOE Contract Number:  
DE-AC02-07CH11358
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry B
Additional Journal Information:
Journal Volume: 2012; Journal Issue: 116
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Wang, Wenjie, Anderson, Nathaniel A, Travesset, Alex, and Vaknin, David. Regulation of the Electric Charge in Phosphatidic Acid Domains. United States: N. p., 2012. Web. doi:10.1021/jp303840a.
Wang, Wenjie, Anderson, Nathaniel A, Travesset, Alex, & Vaknin, David. Regulation of the Electric Charge in Phosphatidic Acid Domains. United States. doi:10.1021/jp303840a.
Wang, Wenjie, Anderson, Nathaniel A, Travesset, Alex, and Vaknin, David. Sat . "Regulation of the Electric Charge in Phosphatidic Acid Domains". United States. doi:10.1021/jp303840a.
@article{osti_1047712,
title = {Regulation of the Electric Charge in Phosphatidic Acid Domains},
author = {Wang, Wenjie and Anderson, Nathaniel A and Travesset, Alex and Vaknin, David},
abstractNote = {Although a minor component of the lipidome, phosphatidic acid (PA) plays a crucial role in nearly all signaling pathways involving cell membranes, in part because of its variable electrical charge in response to environmental conditions. To investigate how charge is regulated in domains of PA, we applied surface-sensitive X-ray reflectivity and fluorescence near-totalreflection techniques to determine the binding of divalent ions (Ca2+ at various pH values) to 1,2-dimyristoyl-sn-glycero-3-phosphate (DMPA) and to the simpler lipid dihexadecyl phosphate (DHDP) spread as monolayers at the air/water interface. We found that the protonation state of PA is controlled not only by the pKa and local pH but also by the strong affinity to PA driven by electrostatic correlations from divalent ions and the cooperative effect of the two dissociable protons, which dramatically enhance the surface charge. A precise theoretical model is presented providing a general framework to predict the protonation state of PA. Implications for recent experiments on charge regulation by hydrogen bonding and the role of pH in PA signaling are discussed in detail.},
doi = {10.1021/jp303840a},
journal = {Journal of Physical Chemistry B},
number = 116,
volume = 2012,
place = {United States},
year = {2012},
month = {5}
}