Cholesterol affects the binding of proteins to phosphatidic acid without influencing its ionization properties
File(s)
Published version
Author(s)
Type
Journal Article
Abstract
Phosphatidic acid (PA) through its unique negatively charged phosphate headgroup binds to various proteins to modulate multiple cellular events. To perform such diverse signaling functions, the ionization and charge of PA's headgroup rely on the properties of vicinal membrane lipids and changes in cellular conditions. Cholesterol has conspicuous effects on lipid properties and membrane dynamics. In eukaryotic cells, its concentration increases along the secretory pathway, reaching its highest levels toward the plasma membrane. Moreover, membrane cholesterol levels are altered in certain diseases such as Alzheimer's disease, cancer, and in erythrocytes of hypercholesteremia patients. Hence, those changing levels of cholesterol could affect PA's charge and alter binding to effector protein. However, no study has investigated the direct impact of cholesterol on the ionization properties of PA. Here, we used 31P MAS NMR to explore the effects of increasing cholesterol concentrations on the chemical shifts and pKa2 of PA. We find that, while the chemical shifts of PA change significantly at high cholesterol concentrations, surprisingly, the pKa2 and charge of PA under these conditions are not modified. Furthermore, using in vitro lipid binding assays we found that higher cholesterol levels increased PA binding of the Spo20p PA sensor. Finally, in cellulo experiments demonstrated that depleting cholesterol from neurosecretory cells halts the recruitment of this sensor upon PA addition. Altogether, these data suggest that the intracellular cholesterol gradient may be an important regulator of proteins binding to PA and that disruption of those levels in certain pathologies may also affect PA binding to its target proteins and subsequent signaling pathways.
Date Issued
2025-03-01
Date Acceptance
2025-01-01
Citation
Journal of Lipid Research, 2025, 66 (3)
ISSN
0022-2275
Publisher
Elsevier BV
Journal / Book Title
Journal of Lipid Research
Volume
66
Issue
3
Copyright Statement
©2025 THE AUTHORS. Published by Elsevier Inc on behalf of American Society for Biochemistry and Molecular Biology. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Identifier
https://www.ncbi.nlm.nih.gov/pubmed/39880167
PII: S0022-2275(25)00009-4
Subjects
Signaling lipids
cholesterol
lipid-protein interactions
phosphatidic acid
Phosphatidic Acids
Cholesterol
Protein Binding
Humans
Publication Status
Published
Coverage Spatial
United States
Article Number
100749
Date Publish Online
2025-01-27