title: An alternative respiratory pathway on Candida krusei: implications on susceptibility profile and oxidative stress.
abstract: Our aim was to detect the presence of an alternative oxidase (AOX) in Candida krusei clinical strains and its influence on fluconazole susceptibility and in reactive oxygen species (ROS) production. Candida krusei clinical isolates were tested to evaluate the presence of AOX. Debaromyces hansenii 2968 (AOX positive) and Saccharomyces cerevisiae BY4742 (AOX negative) were used as control strains. Measurements of oxygen consumption were performed in the presence of 1 mM KCN, an inhibitor of the classical respiratory chain, and 5 mM salicylhydroxamic acid (SHAM). AOX expression was monitored by Western blotting using an AOX monoclonal antibody. Interactions between fluconazole and SHAM were performed using checkerboard assay. ROS production was evaluated in the presence of SHAM plus fluconazole, H(2) O(2) , menadione, or plumbagin. AOX was present in all C. krusei tested. The combination of fluconazole with SHAM resulted in an indifferent effect. In the presence of SHAM, the treatment with ROS inductors or fluconazole increased ROS production, except in the AOX-negative strain. An alternative respiratory pathway resistant to cyanide is described for the first time as a characteristic of C. krusei species. This AOX is unrelated to fluconazole resistance; however, it protects C. krusei from oxidative stress.
authors.affiliation: Department of Microbiology, University of Porto, Porto, Portugal. sqco@med.up.pt
authors.forename: Sofia
authors.initials: S
authors.lastname: Costa-de-Oliveira
authors.forename: Belém
authors.initials: B
authors.lastname: Sampaio-Marques
authors.forename: Matilde
authors.initials: M
authors.lastname: Barbosa
authors.forename: Elisabete
authors.initials: E
authors.lastname: Ricardo
authors.forename: Cidália
authors.initials: C
authors.lastname: Pina-Vaz
authors.forename: Paula
authors.initials: P
authors.lastname: Ludovico
authors.forename: Acácio G
authors.initials: AG
authors.lastname: Rodrigues
mesh_terms: D000935:Antifungal Agents / Q000494:pharmacology*; D015153:Blotting, Western; D002175:Candida / Q000187:drug effects* / Q000201:enzymology / Q000302:isolation & purification / Q000378:metabolism*; D002177:Candidiasis / Q000382:microbiology; D055165:Debaryomyces / Q000187:drug effects; D015725:Fluconazole / Q000494:pharmacology*; D020869:Gene Expression Profiling; D006801:Humans; D053858:Metabolic Networks and Pathways / Q000235:genetics*; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism; D016877:Oxidants / Q000378:metabolism; D018384:Oxidative Stress; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000187:drug effects; D000099188:Alternative Oxidase
chemical_list: D000935:Antifungal Agents; D015725:Fluconazole; D024101:Mitochondrial Proteins; D016877:Oxidants; D010088:Oxidoreductases; D010100:Oxygen; D010940:Plant Proteins; D017382:Reactive Oxygen Species; D000099188:Alternative Oxidase