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BioMetals

, Volume 25, Issue 4, pp 737–747 | Cite as

Transcriptomic response of Enterococcus faecalis to iron excess

  • Guadalupe López
  • Mauricio Latorre
  • Angélica Reyes-Jara
  • Verónica Cambiazo
  • Mauricio González
Article

Abstract

Iron is an essential nutrient for sustaining bacterial growth; however, little is known about the molecular mechanisms that govern gene expression during the homeostatic response to iron availability. In this study we analyzed the global transcriptional response of Enterococcus faecalis to a non-toxic iron excess in order to identify the set of genes that respond to an increment of intracellular iron. Our results showed an up-regulation of transcriptional regulators of the Fur family (PerR and ZurR), the cation efflux family (CzcD) and ferredoxin, while proton-dependent Mn/Fe (MntH) transporters and the universal stress protein (UspA) were down-regulated. This indicated that E. faecalis was able to activate a transcriptional response while growing in the presence of an excess of non-toxic iron, assuring the maintenance of iron homeostasis. Gene expression analysis of E. faecalis treated with H2O2 indicated that a fraction of the transcriptional changes induced by iron appears to be mediated by oxidative stress. A comparison of our transcriptomic data with a recently reported set of differentially expressed genes in E. faecalis grown in blood, revealed an important fraction of common genes. In particular, genes associated to oxidative stress were up-regulated in both conditions, while genes encoding the iron uptake system (feo and ycl operons) were up-regulated when cells were grown in blood. This suggested that blood cultures mimic an iron deficit, and was corroborated by measuring feo and ycl expression in E. faecalis treated with the iron chelating agent 2,2-dipyridil. In summary, our group identified an adaptive transcriptional mechanism in response to metal ion stress in E. faecalis, providing a foundation for future in-depth functional studies of the iron-activated regulatory network.

Keywords

Enteroccocus faecalis Iron transporters Global gene expression qPCR Iron content Oxidative stress 

Notes

Acknowledgments

This work was supported by Fondo Nacional de Desarrollo Científico y Tecnológico, FONDECYT (grants 1110427 to MG and 1090211 to VC) and Fondo Nacional de Desarrollo de Areas Prioritarias, FONDAP, project number 15090007, Center for Genome Regulation (CGR) to MG and VC. AR-J is recipient of the “Inserción de Capital Humano Avanzado en la Academia from CONICYT” grant, number 791100002. ML is a recipient of a Doctoral fellowship from CONICYT.

Supplementary material

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Supplementary material 1 (DOC 82 kb)
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Supplementary material 2 (XLS 36 kb)
10534_2012_9539_MOESM3_ESM.xls (354 kb)
Supplementary material 3 (XLS 353 kb)

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Copyright information

© Springer Science+Business Media, LLC. 2012

Authors and Affiliations

  • Guadalupe López
    • 1
    • 2
  • Mauricio Latorre
    • 1
  • Angélica Reyes-Jara
    • 1
    • 3
  • Verónica Cambiazo
    • 1
    • 4
  • Mauricio González
    • 1
    • 4
    • 5
  1. 1.Laboratorio de Bioinformática y Expresión Génica, INTAUniversidad de ChileSantiagoChile
  2. 2.Laboratorio de Nutrición MolecularUniversidad Autónoma del Estado de HidalgoPachucaMexico
  3. 3.Laboratorio de Microbiología y Probióticos, INTAUniversidad de ChileSantiagoChile
  4. 4.Fondap-Center of Genome RegulationUniversidad de ChileSantiagoChile
  5. 5.Laboratorio de Bioinformática y Matemática del Genoma, Centro de Modelamiento Matemático (UMI 2807, CNRS) Facultad de Ciencias Físicas y MatemáticasUniversidad de ChileSantiagoChile

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