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Electronic Journal of Biotechnology
Universidad Católica de Valparaíso
ISSN: 0717-3458
Vol. 29, No. 1, 2017, pp. 1-6
Bioline Code: ej17056
Full paper language: English
Document type: Research Article
Document available free of charge

Electronic Journal of Biotechnology, Vol. 29, No. 1, 2017, pp. 1-6

 en Putative 3-nitrotyrosine detoxifying genes identified in the yeast Debaryomyces hansenii check for this species in other resources : In silico search of regulatory sequences responsive to salt and nitrogen stress
Castro, Daniela E.; Murguía-Romero, Miguel; Thomé, Patricia E.; Peña, Antonio & Calderón-Torres, Marissa

Abstract

Background: During salt stress, the yeast Debaryomyces hansenii synthesizes tyrosine as a strategy to avoid the oxidation of proteins. Tyrosine reacts with nitrogen radicals to form 3-nitrotyrosine. 3-nitrotyrosine prevents the effects of associated oxidative stress and thus contributes to the high halotolerace of the yeast. However, the mechanism of how D. hansenii counteracts the presence of this toxic compound is unclear. In this work, we evaluated D. hansenii's capacity to assimilate 3-nitrotyrosine as a unique nitrogen source and measured its denitrase activity under salt stress. To identify putative genes related to the assimilation of 3-nitrotyrosine, we performed an in silico search in the promoter regions of D. hansenii genome.
Results: We identified 15 genes whose promoters had binding site sequences for transcriptional factors of sodium, nitrogen, and oxidative stress with oxidoreductase and monooxygenase GO annotations. Two of these genes, DEHA2E24178g and DEHA2C00286g, coding for putative denitrases and having GATA sequences, were evaluated by RT-PCR and showed high expression under salt and nitrogen stress.
Conclusions: D. hansenii can grow in the presence of 3-nitrotyrosine as the only nitrogen source and has a high specific denitrase activity to degrade 3-nitrotyrosine in 1 and 2 M NaCl stress conditions. The results suggest that given the lack of information on transcriptional factors in D. hansenii, the genes identified in our in silico analysis may help explain 3-nitrotyrosine assimilation mechanisms.

Keywords
Extremophiles; Free tyrosine; Halotolerance; Irreversible damages; Neutralization of free radicals; Nitrogen source; Osmoregulatory mechanisms; Oxidative stress; Salt-tolerant yeast; Transcriptional factors (TF); Tyrosine synthesis

 
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