The expression of alternative oxidase and its impact on the supramolecular organization of the electron transport system and mitochondrial ultrastructure

• Grant number: 24/20222-2
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: April 01, 2025
• End date: July 31, 2028
• Field of knowledge: Biological Sciences - Biochemistry - Metabolism and Bioenergetics
• Principal Investigator: Marcos Túlio de Oliveira
• Grantee: Murilo Ferreira Othonicar
• Host Institution: Faculdade de Medicina de Ribeirão Preto (FMRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil
• Associated research grant: 21/06711-2 - Modulation of tissue growth and biomass accumulation by the mitochondrial alternative oxidase, AP.JP2

Abstract

The mitochondria's electron transport system (ETS) complexes, notably I, III and IV, can organize themselves into supramolecular structures called supercomplexes (SCs). SCs appear to be capable of facilitating electron flow during oxidative phosphorylation (OXPHOS) and reducing the formation of reactive oxygen species (ROS). Furthermore, in conjunction with ATP synthase dimers, SCs contribute in the formation of mitochondrial cristae. Although SCs are present in many species, tunicates such as Ciona intestinalis lack most of the genes necessary to form them. However, unlike vertebrates and insects, tunicates have alternative enzymes capable of reducing the formation of ROS, such as AOX, which provides an additional route for electron transfer, partially replacing the functions of complexes III and IV. The xenotopic expression of AOX from C. intestinalis in model organisms has shown therapeutic potential against several mitochondrial dysfunctions. However, preliminary data suggest that AOX modifies the organization of the ETS, increasing the proportion of SCs, ATP synthase dimers, and mitochondrial cristae in Drosophila melanogaster larvae. This project aims to investigate the effects of the xenotopic expression of AOX from C. intestinalis on the composition and organization of the ETS, and on mitochondrial ultrastructure. of D. melanogaster and human cells in culture. We will use advanced biochemistry and cell biology techniques, such as native-blue polyacrylamide gel electrophoresis, mass spectrometry and cryoelectron tomography, to evaluate the impacts of AOX expression and explore its therapeutic potential, and its effects on mitochondrial dynamics and OXPHOS.