g , chromate), and a link between iron transport and heavy metal

g., chromate), and a link between iron transport and heavy metal sensitivity has been suggested

[15, 17]. It is possible that sequestration of iron prevents redox cycling between ferrous iron and chromate, which can lead to reactive intermediates and oxidative stress [18, 19]. A consequence of this may be deficient intracellular iron concentrations that could inhibit growth. A cyclical response would ensue, resulting in up-regulation of iron uptake genes such as those involved in siderophore biosynthesis, which is similar to what has been demonstrated for S. oneidensis in response to chromate stress [15, 16, 20]. GDC0449 The aim of the present study was to examine the function of the uncharacterized SO2426 response regulator within the context of siderophore biosynthesis. We used

a bioinformatics approach to map putative SO2426-binding domains and biochemical assays to demonstrate the binding of SO2426 to predicted recognition sites. Electrophoretic mobility shift assays showed that a recombinant SO2426 protein binds to a putative SO2426 motif that exists within the operator region of the so3030-3031-3032 operon. Siderophore detection assays further showed a diminished capacity of the Δso2426 mutant strain to produce siderophores, particularly in the presence of the iron chelator 2,2′-dipyridyl. Based on the identification of a Fur-binding motif upstream of the predicted SO2426-binding site within the operator region of the so3030-3031-3032 operon, we postulate that there Liothyronine Sodium are likely multiple levels of regulation operating in S. oneidensis MR-1 to precisely adjust intracellular Ricolinostat solubility dmso iron levels in response to cellular needs. These intricate control mechanisms appear to involve Fur-mediated repression and Galunisertib price derepression as well as SO2426-mediated activation of siderophore biosynthesis

genes. Results and Discussion Conservation of SO2426 amino acid sequence among Shewanellae Previously, we reported that the so2426 gene of S. oneidensis MR-1 shares 27 to 36% sequence identity at the amino acid level to CpxR and OmpR orthologs from Vibrio cholerae and Escherichia coli [21]. Orthologs of SO2426 were also identified in a number of Shewanella species. Multiple sequence alignment of all available Shewanella SO2426 orthologs revealed a high degree of conservation at key residues (Figure 1). The predicted phosphorylation residues (D18, D19, D62, and K109) associated with the N-terminal CheY-like response regulator domain of SO2426 [21] are highly conserved among Shewanella orthologs. Another striking feature is the high degree of sequence conservation among the C-terminal or output domains of the SO2426 orthologs. This region contains several features of OmpR winged-helix transcriptional regulators such as the output domain, encompassed by residues T225, G230, and Y231 [22]. Residues 204-215 (LDMHISNTRRKL) resemble the predicted α3-helical region of E.

Comments are closed.