A thermodynamic model describing the nature of the crista junction: a structural motif in the mitochondrion

The use of electron tomography has allowed the three-dimensional membrane topography of the mitochondrion to be better understood. The most striking feature of this topology is the crista junction, a structure that may serve to divide functionally the inner membrane and intermembrane spaces. In situ...

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Bibliographic Details
Published in:Journal of structural biology 2002-04, Vol.138 (1), p.137-144
Main Authors: Renken, Christian, Siragusa, Gino, Perkins, Guy, Washington, Lance, Nulton, Jim, Salamon, Peter, Frey, Terrence G.
Format: Article
Language:English
Subjects:
Animals
Electron tomography
Image Processing, Computer-Assisted - methods
Imaging, Three-Dimensional - methods
Intracellular Membranes - ultrastructure
Membrane topology
Microscopy, Electron
Mitochondria
Mitochondria - ultrastructure
Mitochondrial Swelling
Modeling
Models, Biological
Spontaneous curvature
Thermodynamics
Tomography, X-Ray Computed
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Summary:The use of electron tomography has allowed the three-dimensional membrane topography of the mitochondrion to be better understood. The most striking feature of this topology is the crista junction, a structure that may serve to divide functionally the inner membrane and intermembrane spaces. In situ these junctions seem to have a preferred size and shape independent of the source of the mitochondrion with few exceptions. When mitochondria are isolated and have a condensed matrix the crista junctions enlarge and become nondiscrete. Upon permeation of the inner membrane and subsequent swelling of the matrix space, the uniform circular nature of the crista junction reappears. We examine the distribution of shapes and sizes of crista junctions and suggest a thermodynamic model that explains the distribution based on current theories of bilayer membrane shapes. The theory of spontaneous curvature shows the circular junction to be a thermodynamically stable structure whose size and shape is influenced by the relative volume of the matrix. We conclude that the crista junction exists predominantly as a circular junction, with other shapes as exceptions made possible by specific characteristics of the lipid bilayer.
ISSN:1047-8477
1095-8657
DOI:10.1016/S1047-8477(02)00012-6