pH Sensing by Lipids in Membranes: The Fundamentals of pH-driven Migration, Polarization and Deformations of Lipid Bilayer Assemblies

TL;DR

This paper reviews how pH gradients influence lipid membrane behaviors such as migration, polarization, and deformation, highlighting recent experimental and theoretical insights into their biological significance.

Contribution

It provides a comprehensive overview of the mechanisms by which pH variations affect lipid bilayer properties and introduces a theoretical framework for pH-induced membrane deformations.

Findings

pH gradients drive lipid membrane migration and polarization

Theoretical models explain pH-induced membrane deformations

Application to mitochondrial cristae stability

Abstract

Most biological molecules contain acido-basic groups that modulate their structure and interactions. A consequence is that pH gradients, local heterogeneities and dynamic variations are used by cells and organisms to drive or regulate specific biological functions including energetic metabolism, vesicular traffic, migration and spatial patterning of tissues in development. While the direct or regulatory role of pH in protein function is well documented, the role of hydrogen and hydroxyl ions in modulating the properties of lipid assemblies such as bilayer membranes is only beginning to be understood. Here, we review approaches using artificial lipid vesicles that have been instrumental in providing an understanding of the influence of pH gradients and local variations on membrane vectorial motional processes: migration, membrane curvature effects promoting global or local deformations, crowding generation by segregative polarization processes. In the case of pH induced local deformations, an extensive theoretical framework is given and an application to a specific biological issue, namely the structure and stability of mitochondrial cristae, is described.