|dc.description.abstract||The oxidative phosphorylation system comprises three fundamental processes: electron transport, proton pumping and ATP synthesis. Electron transport is required for both anabolic and catabolic processes, which require the delivery of electrons to the mitochondrial electron chain. This flux of electrons drives proton pumping and generates an electrochemical gradient across the mitochondrial inner membrane. This gradient is used by ATP synthase (ATPase, complex V) to generate ATP. Electron transport and proton pumping can be detached in many non-mammalian eukaryotes because they have nonproton-pumping oxidases. Mitochondrial ATPase is structured in two domains, the FO domain, hydrophobic and embedded in the mitochondrial inner membrane, and the F1 domain, hydrophilic, which protrudes through the mitochondrial matrix and is responsible for the ATP synthesis from ADP and Pi. In recent years, new ATPase subunits have been discovered: DAPIT and 6.8kDa protein (MP68). Very little is known about them, but DAPIT has been related with glucose metabolism and diabetes. They have been recently reported to form an ATPase subdomain called the intermembrane space domain (IMD), formed by only these two proteins. In this thesis, the functional role of DAPIT and MP68 was evaluated by generating knockout mouse models. An opposite role for each one was demonstrated: while DAPIT promotes ATPase dimerisation, MP68 prevents it. In the absence of DAPIT, an ATPase subcomplex is dissociated, which indicates that DAPIT promotes ATPase structure maintenance.
Next we focused on developing cellular tools where mitochondrial ATP synthesis capacity could be studied separately from electron transport. For this purpose, we designed optogenetic tools to generate an electrochemical gradient in mitochondria. Optogenetic tools were initially used in the neural field to modify and control the channel flux in neurons to alter their activity. Here we transformed light energy into an energy, that cells can use to grow. By expressing deltarhodopsin in mammalian cells, we were able to rescue energy deficiencies using light as a source of energy.||es_ES