Análise evolutiva do genoma mitocondrial de leveduras : perda do complexo I

• Ano de defesa: 2017
• Autor(a) principal: Lopes, Luciano Rodrigo [UNIFESP]
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de São Paulo (UNIFESP)
• Palavras-chave em Português: Genome; Mitochondrial; Phylogeny; Yeast fungi; Genoma; Mitocondria; Leveduras; Filogenia; Relógio molecular
• Link de acesso: https://sucupira.capes.gov.br/sucupira/public/consultas/coleta/trabalhoConclusao/viewTrabalhoConclusao.jsf?popup=true&id_trabalho=5565257; http://repositorio.unifesp.br/handle/11600/50680

The evolution of mitochondrial genomes is essential for the adaptation of yeasts to the variation of environmental levels of oxygen. Although Saccharomyces cerevisiae mitochondrial DNA lacks all complex I genes, respiration is possible because alternative NADH dehydrogenases are encoded by NDE1 and NDI1 nuclear genes. The proposed whole genome duplication (WGD) in the yeast ancestor at 150-100 million years ago caused nuclear gene duplications and secondary losses, although its relation to the loss of complex I mitocondrial is unknown. Here we present phylogenomic supertrees and supermatix tree of 46 mitochondrial genomes showing that the loss of complex I predates WGD and occurred independently in the Saccharomyces cerevisiae group and the fission yeast Schizosaccharomyces pombe. We also showed that the pattern of branching trees did not deviate dramatically between supertrees and supermatrix phylogenetic tree. Phylogeny indicated consistent relations between conserved mitochondrial gene order with closely related yeast species. Correlation of the mitochondrial genes based molecular clock estimatives with variations of atmospheric oxygen concentrations data in the Phanerozoic suggests that the Saccharomyces lineage might have lost the complex I during hypoxic periods near Perminian-Triassic or Triassic-Jurassic mass extinction events. While Schizosaccharomyces lineage possibly lost the complex I during hypoxic environment periods during Middle Cambrian until Lower Devonian, a long period under hipoxya. Loss of mitochondrial complex I during low offering oxygen might not improved yeast metabolism. However, the return to increased oxygen environment periods might to pressed alternative adaptations from respiratory process. Thus, we also showed that NDE1 and NDI1 based phylogenies suggest evolutionary convergence in yeasts where mitochondrial complex I is absent.