Transition metals are essential for life by acting as cofactors in various biochemical reactions. In bacteria, metal homeostasis involves regulatory metalloproteins that sense different metals and lead to the activation or repression of genes. The metalloprotein Fur senses the iron levels to mediate derepression of iron uptake systems under iron limitation and activation of storage and efflux systems in iron excess. Recently, other families of transcription factors have been described as metal-responsive, such as the MarR family. During this ongoing Doctorate project, we performed a screening of a 10,000-transposon mutant library at high iron concentrations to find new genes involved in alleviating iron toxicity in Chromobacterium violaceum, an environmental bacterium that occasionally causes severe infections in humans. Among the strains with growth impairment in the presence of iron, we selected to further characterization in this BEPE project one mutant strain with transposon insertion inside the gene CV_3659. It encodes a probable transcription factor of the GbsR subfamily, a member of the MarR family. The CV_3659 appears to be an operon with CV_3658 and CV_3657 that encode a cytochrome bd oxidase. In this project, we will test the hypothesis that the operon CV_3659-58-57 is required for C. violaceum protection against iron toxicity and oxidative stress. We will use several genetic, microbiological, and biochemical approaches to perform functional characterization of the CV_3659-58-57 operon in C. violaceum.
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