pH gradient-driven deformation of a crista-like vesicle

TL;DR

This paper models mitochondrial cristae as vesicles influenced by proton gradients, revealing how pH-driven forces shape their structure and function, with implications for understanding ATP synthesis efficiency.

Contribution

It introduces a biophysical model of crista shape deformation driven by pH gradients using Helfrich theory, linking membrane curvature to mitochondrial function.

Findings

Identifies shape regimes of vesicles under pH gradients.

Defines a functionality score correlating shape with efficiency.

Constructs a phase diagram of crista configurations.

Abstract

The inner membrane of mitochondria presents folds, the cristae, which are the production place of ATP. This synthesis is driven by a flow of protons confined to the surface of the membrane, which also shapes the crista to ensure a high synthesis rate. We model a crista as a spherical vesicle submitted to a diffusive proton gradient flowing from the poles to the equator. Using Helfrich model, we introduce a pH-dependent spontaneous curvature for the membrane and determine the shape of the vesicle, when submitted to the pH gradient, in the regime of small deformations. Based on biophysical arguments, we define a functionality score for the vesicle and construct a phase diagram identifying the zones of "well-functioning" cristae, which we compare to experimental measurements.