title: High Osmolarity Environments Activate the Mitochondrial Alternative Oxidase in Debaryomyces Hansenii.
abstract: The oleaginous yeast Debaryomyces hansenii is a good model to understand molecular mechanisms involved in halotolerance because of its impressive ability to survive under a wide range of salt concentrations. Several cellular adaptations are implicated in this response, including the presence of a cyanide-insensitive ubiquinol oxidase (Aox). This protein, which is present in several taxonomical orders, has been related to different stress responses. However, little is known about its role in mitochondria during transitions from low to high saline environments. In this report, we analyze the effects of Aox in shifts from low to high salt concentrations in the culture media. At early stages of a salt insult, we observed that this protein prevents the overflow of electrons on the mitochondrial respiratory chain, thus, decreasing the production of reactive oxygen species. Interestingly, in the presence of high osmolite concentrations, Aox activity is able to sustain a stable membrane potential when coupled to complex I, despite a compromised cytochrome pathway. Taken together, our results suggest that under high osmolarity conditions Aox plays a critical role regulating mitochondrial physiology.
authors.affiliation: Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Wilson
authors.initials: W
authors.lastname: Garcia-Neto
authors.affiliation: Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México, México.
authors.forename: Alfredo
authors.initials: A
authors.lastname: Cabrera-Orefice
authors.affiliation: Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México, México.
authors.forename: Salvador
authors.initials: S
authors.lastname: Uribe-Carvajal
authors.affiliation: Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Alicia J
authors.initials: AJ
authors.lastname: Kowaltowski
authors.affiliation: Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Luis
authors.initials: L
authors.lastname: Alberto Luévano-Martínez
mesh_terms: D001203:Ascomycota / Q000502:physiology*; D019069:Cell Respiration; D002470:Cell Survival; D004579:Electron Transport; D045222:Electron Transport Chain Complex Proteins / Q000378:metabolism; D053078:Membrane Potential, Mitochondrial; D008928:Mitochondria / Q000378:metabolism*; D024101:Mitochondrial Proteins; D009994:Osmolar Concentration; D010084:Oxidation-Reduction; D010088:Oxidoreductases; D010940:Plant Proteins; D013312:Stress, Physiological; D000099188:Alternative Oxidase
chemical_list: D045222:Electron Transport Chain Complex Proteins; D024101:Mitochondrial Proteins; D010088:Oxidoreductases; D010940:Plant Proteins; D000099188:Alternative Oxidase