Topology of the Mitochondrial Inner Membrane: Dynamics and Bioenergetic Implications

Citations Over TimeTop 10% of 2001 papers

Abstract

Electron tomography indicates that the mitochondrial inner membrane is not normally comprised of baffle-like folds as depicted in textbooks. In actuality, this membrane is pleomorphic, with narrow tubular regions connecting the internal compartments (cristae) to each other and to the membrane periphery. The membrane topologies observed in condensed (matrix contracted) and orthodox (matrix expanded) mitochondria cannot be interconverted by passive folding and unfolding. Instead, transitions between these morphological states likely involve membrane fusion and fission. Formation of tubular junctions in the inner membrane appears to be energetically favored, because they form spontaneously in yeast mitochondria following large-amplitude swelling and recontraction. However, aberrant, unattached, vesicular cristae are also observed in these mitochondria, suggesting that formation of cristae junctions depends on factors (such as the distribution of key proteins and/or lipids) that are disrupted during extreme swelling. Computer modeling studies using the "Virtual Cell" program suggest that the shape of the inner membrane can influence mitochondrial function. Simulations indicate that narrow cristae junctions restrict diffusion between intracristal and external compartments, causing depletion of ADP and decreased ATP output inside the cristae.

Related Papers

• → Biogenesis of Mitochondrial Proteins(2012)42 cited
• → Mitochondrial preprotein translocases as dynamic molecular machines(2006)60 cited
• → Chapter 5 New Insights into the Mechanism of Precursor Protein Insertion into the Mitochondrial Membranes(2008)14 cited
• CHARACTERIZATION OF MITOCHONDRIAL MEMBRANE PROTEINS AS NOVEL COMPONENTS IN MITOCHONDRIAL DYNAMICS(2014)
• Molecular interaction of Mitofusin 2 and its role inmitochondrial fusion(2009)