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A genetic analysis of the response of Escherichia coli to cobalt stress
Author(s) -
Fantino JeanRaphaël,
Py Béatrice,
Fontecave Marc,
Barras Frédéric
Publication year - 2010
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/j.1462-2920.2010.02265.x
Subject(s) - biogenesis , biology , operon , cobalt , escherichia coli , transcriptome , gene , microarray analysis techniques , gene expression , genetics , microbiology and biotechnology , chemistry , inorganic chemistry
Summary Cobalt can be toxic and the way cells adapt to its presence is largely unknown. Here we carried out a transcriptomic analysis of Escherichia coli exposed to cobalt. A limited number of genes were either up‐ or downregulated. Upregulated genes include the isc and the nfuA genes encoding Fe/S biogenesis assisting factors, and the rcnA gene encoding a cobalt efflux system. Downregulated genes are implicated in anaerobic metabolism ( narK , nirB , hybO , grcA ), metal transport ( feoB , nikA ), sulfate/thiosulfate import ( cysP ), and one is of unknown function ( yeeE ). Cobalt regulation of isc , nfuA , hybO , cysP and yeeE genes was found to involve IscR, a Fe/S transcriptional regulator. Previously, the Suf Fe/S biogenesis machinery was found to be important for cobalt stress adaptation, but suf genes did not show up in the microarray analysis. Therefore, we used qRT‐PCR analysis and found that cobalt induced the suf operon expression. Moreover, kinetic analysis of the cobalt‐mediated induction of the suf operon expression allowed us to propose that cobalt toxicity is caused first by impaired Fe/S biogenesis, followed by decreased iron bioavailability and eventually oxidative stress.