Determination of the mitochondrial ATP synthase structure by cryo-electron tomography and subtomogram averaging.

Abstract

The mitochondria are the cellular organelles that is responsible for respiration in eukaryotic, aerobic organisms. The enzyme ATP synthase is the site of oxidative phosphorylation, the generation of energy for cellular use in the form of ATP. The structure and location of this enzyme within the mitochondria and the cell is vital to its function. However, the crowded cellular environment prevents traditional methods of microscopy structural analysis from effectively gathering information about molecular structures in situ. Rather than existing as single monomers, ATP synthase adopts a dimeric conformation when found in its natural location, along the inner membrane of a mitochondrion. The use of cryoelectron tomography, therefore, is crucial in the quest to learn about this enzyme. When combined with computational analyses such as subtomogram averaging, this method can resolve the structure of macromolecular complexes like ATP synthase. In this investigation, we modified and optimized existing techniques of cryo-ET and subtomogram averaging to determine the structure of mitochondrial ATP synthase in insulin producing pancreatic cells.