Genome-wide characterization of the Fur regulatory network reveals a link between catechol degradation and bacillibactin metabolism in Bacillus subtilis

The goal of this study is to obtain a genomic view of the Fur regulatory network under both iron replete and iron deficient conditions in Bacillus subtilis using ChIP-seq. Besides the known Fur target sites, 70 putative DNA binding sites were identified, and the vast majority had higher occupancy under iron sufficient conditions. In addition,we discovered a role for catechol degradation in bacillibactin metabolism, and provided evidence that catechol 2,3-dioxygenase can detoxify endogenously produced catechol substrates in addition to its more widely studied role in biodegradation of environmental aromatic compounds and pollutants. To modulate intracellular iron levels, we employed a high-affinity Fe2+ exporter FrvA from L. monocytogenes to impose iron starvation. Bacillus wild-type cells (with C-terminal FLAG-tagged Fur at its native locus and an IPTG-inducible ectopic copy of frvA integrated at amyE locus) were harvested at 0 and 30 min after IPTG induction to study Fur-dependent regulation under iron sufficient and deficient conditions, respectively.