Mitochondria are the powerhouses of our cells, generating energy in the form of chemical compounds such as ATP. To do this job effectively, mitochondria have a characteristic organisation: In addition to an outer membrane, they have an inner membrane with many invaginations. On this inner membrane are all the enzymes essential to the production of ATP.
"We were interested in how mitochondria acquire and maintain their characteristic shape," says Professor Oliver Daumke, leader of the MDC research group Structural Biology of Membrane-Associated Processes and one of the two senior authors of the study published in Nature. "The fact is that mitochondria are not rigid organelles -- they are continuously dividing and fusing with each other." One result of this process is that damaged sections are removed.
Mitochondria - Dr - Katja - Faelber - Crystallography
"But the mitochondria don't always function so perfectly," explains Dr. Katja Faelber from the Crystallography Department at the MDC, one of the study's two first authors. "Many neurodegenerative diseases, such as Alzheimer's and Parkinson's disease, are the result of an imbalance between mitochondrial fission and fusion, which causes neurons to slowly die off."
Key players in the remodelling of the mitochondrial membrane are the mitochondrial genome maintenance protein 1 (Mgm1) in yeats and the optic atrophy protein 1 (OPA1) in humans. Mutations in the gene for OPA1 lead to a hereditary disease of the optic nerve known as optic atrophy, one of the most common causes of congenital blindness.
Mgm1 - OPA1 - Membrane - Invaginations - Oliver
"Mgm1 and OPA1 are located on the inner mitochondrial membrane, particularly close to the characteristic invaginations," explains Oliver Daumke. Here the proteins function as molecular machines, converting chemical energy into mechanical energy.
Prior to this study, it was already known that the proteins consist of several sub-units: of the GTPase domain, which functions as the actual motor, of the BSE (bundle signalling element) domain, which acts as a lever, and...
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