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Congresso Brasileiro de Microbiologia 2023
 		Resumo: 895-1

895-1

From nuclear to mitochondrial genome: coupled assembly of cytochrome oxidase and ATP synthase in Saccharomyces cerevisiae expressing allotopic mitochondrial COX6

Autores:
Leticia Veloso Ribeiro Franco (ICB USP - Instituto de Ciências Biomédicas, Universidade de São Paulo, CU - Columbia University, Department of Biological Sciences) ; Mario Henrique Barros (ICB USP - Instituto de Ciências Biomédicas, Universidade de São Paulo) ; Alexander Tzagoloff (CU - Columbia University, Department of Biological Sciences)

Resumo:
Mitochondria are organelles responsible for producing most of the ATP in our cells. Due to this key role in metabolism, it is not surprising that their dysfunction is associated with many diseases and, therefore, is worth investigating. We use the model organism Saccharomyces cerevisiae to study mitochondrial biogenesis, specifically the assembly of the oxidative phosphorylation complexes. In this work, we have discovered the mechanism that couples the biogenesis of cytochrome oxidase (COX) and ATP synthase in yeast mitochondria. To make this discovery, we transferred a nuclear gene to the mitochondrial genome. COX and ATP Synthase of the yeast S. cerevisiae mitochondria are genetic hybrids with some of their polypeptides encoded in mitochondrial and others in nuclear DNA. Cox6 is a nuclearly encoded subunit of COX and Atp9, a mitochondrially encoded subunit of the ATP synthase. Despite being components of distinct complexes of the respiratory chain, these two protein interact with each other to form high molecular weight Atco complexes. We have previously showed that Atco is the source of Atp9 for the ATP synthase assembly. In the present study we developed a strategy to further study the role of Cox6 in Atco complexes by allotopically expressing it from the mitochondrial genome. The recoded gene Cox6m introduced into the 3’-UTR region of VAR1 in the mitochondrial DNA was able to partially restore respiration of the cox6 null mutant. This strain presented low levels of COX, which may be explained by the presence of most Cox6m as a free subunit and only a small fraction associated with Atp9 in Atco. We also show that atp9 null mutant lacks COX, confirming our hypothesis that Atco couples the biogenesis of COX to that of ATP synthase thereby determining stoichiometric amounts of these two respiratory complexes.

Palavras-chave:
 mitochondrial biogenesis, ATP synthase, cytochrome oxidase, yeast Saccharomyces cerevisiae, oxidative phosphorylation


Agência de fomento:
FAPESP 2019/16015-3, FAPESP 2019/02799-2