title: The mitochondrial alternative oxidase Aox1 is needed to cope with respiratory stress but dispensable for pathogenic development in Ustilago maydis.
abstract: The mitochondrial alternative oxidase is an important enzyme that allows respiratory activity and the functioning of the Krebs cycle upon disturbance of the respiration chain. It works as a security valve in transferring excessive electrons to oxygen, thereby preventing potential damage by the generation of harmful radicals. A clear biological function, besides the stress response, has so far convincingly only been shown for plants that use the alternative oxidase to generate heat to distribute volatiles. In fungi it was described that the alternative oxidase is needed for pathogenicity. Here, we investigate expression and function of the alternative oxidase at different stages of the life cycle of the corn pathogen Ustilago maydis (Aox1). Interestingly, expression of Aox1 is specifically induced during the stationary phase suggesting a role at high cell density when nutrients become limiting. Studying deletion strains as well as overexpressing strains revealed that Aox1 is dispensable for normal growth, for cell morphology, for response to temperature stress as well as for filamentous growth and plant pathogenicity. However, during conditions eliciting respiratory stress yeast-like growth as well as hyphal growth is strongly affected. We conclude that Aox1 is dispensable for the normal biology of the fungus but specifically needed to cope with respiratory stress.
authors.affiliation: Departamento de Bioquímica, Facultad de Medicina, UNAM. Ciudad de México, México.
authors.forename: Christian A
authors.initials: CA
authors.lastname: Cárdenas-Monroy
authors.affiliation: Institute for Microbiology, Cluster of Excellence on Plant Sciences, Department of Biology, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Pohlmann
authors.affiliation: Departamento de Biología Celular y Tisular, Facultad de Medicina, UNAM. Ciudad de México, México.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Piñón-Zárate
authors.affiliation: Departamento de Bioquímica, Facultad de Medicina, UNAM. Ciudad de México, México.
authors.forename: Genaro
authors.initials: G
authors.lastname: Matus-Ortega
authors.affiliation: Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional. Ciudad de México, México.
authors.forename: Guadalupe
authors.initials: G
authors.lastname: Guerra
authors.affiliation: Institute for Microbiology, Cluster of Excellence on Plant Sciences, Department of Biology, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Feldbrügge
authors.affiliation: Departamento de Bioquímica, Facultad de Medicina, UNAM. Ciudad de México, México.
authors.forename: Juan Pablo
authors.initials: JP
authors.lastname: Pardo
mesh_terms: D000220:Adaptation, Biological; D019069:Cell Respiration; D005656:Fungal Proteins / Q000378:metabolism; D015870:Gene Expression; D015966:Gene Expression Regulation, Fungal; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D010101:Oxygen Consumption; D010935:Plant Diseases / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D013312:Stress, Physiological; D013696:Temperature; D014588:Ustilago / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity*; D003313:Zea mays / Q000378:metabolism / Q000382:microbiology; D000099188:Alternative Oxidase
chemical_list: D005656:Fungal Proteins; D024101:Mitochondrial Proteins; D010088:Oxidoreductases; D010940:Plant Proteins; D000099188:Alternative Oxidase