This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Ramalho, P. A. Articles by Ramalho, M. T. Search for Related Content PubMed PubMed Citation Articles by Ramalho, P. A. Articles by Ramalho, M. T. Agricola Articles by Ramalho, P. A. Articles by Ramalho, M. T.

Azo Reductase Activity of Intact Saccharomyces cerevisiae Cells Is Dependent on the Fre1p Component of Plasma Membrane Ferric Reductase

Department of Biology, University of Minho, Campus de Gualtar, 4710-057 Braga,¹ Department of Textile Engineering, University of Minho, Campus de Azurém, 4800-058 Guimarães,² Department of Chemistry, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal³

Received 26 July 2004/ Accepted 22 January 2005

Unspecific bacterial reduction of azo dyes is a process widely studied in correlation with the biological treatment of colored wastewaters, but the enzyme system associated with this bacterial capability has never been positively identified. Several ascomycete yeast strains display similar decolorizing behaviors. The yeast-mediated process requires an alternative carbon and energy source and is independent of previous exposure to the dyes. When substrate dyes are polar, their reduction is extracellular, strongly suggesting the involvement of an externally directed plasma membrane redox system. The present work demonstrates that, in Saccharomyces cerevisiae, the ferric reductase system participates in the extracellular reduction of azo dyes. The S. cerevisiae fre1 and fre1 fre2 mutant strains, but not the fre2 strain, showed much-reduced decolorizing capabilities. The FRE1 gene complemented the phenotype of S. cerevisiae fre1 cells, restoring the ability to grow in medium without externally added iron and to decolorize the dye, following a pattern similar to the one observed in the wild-type strain. These results suggest that under the conditions tested, Fre1p is a major component of the azo reductase activity.

This article has been cited by other articles:

• Ito, K., Nakanishi, M., Lee, W.-C., Zhi, Y., Sasaki, H., Zenno, S., Saigo, K., Kitade, Y., Tanokura, M. (2008). Expansion of Substrate Specificity and Catalytic Mechanism of Azoreductase by X-ray Crystallography and Site-directed Mutagenesis. J. Biol. Chem. 283: 13889-13896 [Abstract] [Full Text]  
• Mizutani, A., Sanuki, R., Kakimoto, K., Kojo, S., Taketani, S. (2007). Involvement of 101F6, a Homologue of Cytochrome b561, in the Reduction of Ferric Ions. J Biochem 142: 699-705 [Abstract] [Full Text]  
• Knight, S. A. B., Dancis, A. (2006). Reduction of 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide inner salt (XTT) is dependent on CaFRE10 ferric reductase for Candida albicans grown in unbuffered media.. Microbiology 152: 2301-2308 [Abstract] [Full Text]  
• Ito, K., Nakanishi, M., Lee, W.-C., Sasaki, H., Zenno, S., Saigo, K., Kitade, Y., Tanokura, M. (2006). Three-dimensional Structure of AzoR from Escherichia coli: AN OXIDEREDUCTASE CONSERVED IN MICROORGANISMS. J. Biol. Chem. 281: 20567-20576 [Abstract] [Full Text]