Mitochondrial membranes have a unique
lipid composition necessary for proper shape and function of the organelle. Mitochondrial lipid metabolism involves biosynthesis of the
phospholipids phosphatidylethanolamine,
cardiolipin and
phosphatidylglycerol, the latter is a precursor of the late endosomal
lipid bis(monoacylglycero)phosphate. It also includes mitochondrial
fatty acid synthesis necessary for the formation of the
lipid cofactor
lipoic acid. Furthermore the synthesis of
coenzyme Q takes place in mitochondria as well as essential parts of the
steroid and
vitamin D metabolism.
Lipid transport and remodelling, which are necessary for tailoring and maintaining specific membrane properties, are just partially unravelled. Mitochondrial
lipids are involved in organelle maintenance, fission and fusion, mitophagy and
cytochrome c-mediated apoptosis. Mutations in TAZ, SERAC1 and AGK affect mitochondrial
phospholipid metabolism and cause
Barth syndrome, MEGDEL and
Sengers syndrome, respectively. In these disorders an abnormal mitochondrial energy metabolism was found, which seems to be due to disturbed
protein-
lipid interactions, affecting especially
enzymes of the oxidative phosphorylation. Since a growing number of
enzymes and transport processes are recognised as parts of the mitochondrial lipid metabolism, a further increase of
lipid-related disorders can be expected.