Ferric uptake regulators (Fur) from Vibrio cholerae and Helicobacter pylori bind a [2Fe–2S] cluster in response to elevation of intracellular free iron content

Ferric uptake regulator (Fur) binds a [2Fe-2S] cluster to regulate intracellular iron homeostasis in Escherichia coli

“…Previously, we found that while the oxidized [2Fe-2S] cluster in E. coli Fur is stable, the reduced [2Fe-2S] cluster in E. coli Fur quickly releases ferrous iron and sulfide to form apo-form Fur ( 26 ). Therefore, we reduced Red-Fur with freshly prepared sodium dithionite in Tris (20 mM, pH 8.0), followed by the dialysis against buffer containing NaCl (500 mM) and Tris (20 mM, pH 8.0) at 4 ° C. Figure 3 A shows that Red-Fur lost the [2Fe-2S] cluster upon reduction of the cluster and dialysis (spectrum 3), as reported previously ( 26 ). Red-Fur before or after removal of the [2Fe-2S] cluster was then subjected to the band shift assay ( Fig.…”

“…Figure 1 B shows that E. coli Fur purified from wildtype E. coli cells grown in M9 medium supplemented with 2,2′-dipyridyl (100 μM) was colorless and had no absorption peaks in the visible range (spectrum 1) ( Apo-Fur ). In contrast, Fur purified from wildtype E. coli cells grown in M9 medium supplemented with Fe(NH 4 ) 2 (SO 4 ) 2 (10 μM) had a bright red color ( Red-Fur ) and distinct absorption peaks at 325 nm, 410 nm, and 450 nm (spectrum 2), indicative of the [2Fe-2S] cluster binding in Fur ( 22 , 26 ). The [2Fe-2S] cluster in Red-Fur was confirmed by the electron paramagnetic resonance and Mössbauer spectroscopy as described previously ( 22 ).…”

CysB Is a Key Regulator of the Antifungal Activity of Burkholderia pyrrocinia JK-SH007

“…Ornibactin is a Bcc-specific siderophore and is the most common type of siderophore, providing hexadentate ligands in 1:1 equivalents to form stable complexes with ferric ions. The activity of ornibactin is probably highest among types of siderophores that can be synthesized by Bcc, but the exact stability constants have not been reported [38,39]. The synthesis of both ornibactin C6 and ornibactin C8 was significantly restored by cysteine supplementation, and we speculate that this may be correlated with the recovery of its antagonism against pathogenic fungi, as ornibactin is thought to be involved in the production of some antifungal substances [49].…”

“…This Here, we list only the targets predicted to be relevant to the process of iron-sulfur metabolism (Table 1). By prediction, we found that Bp_007_sr1, 2, and 3 mainly target the iron-sulfur cluster assembly process, and the putative targets are mainly 2Fe-2S iron-sulfur cluster proteins and Fur proteins, which are important players in maintaining iron homeostasis [38,39]. In addition, Bp_007_sr4 is upregulated after CysB is disrupted, and it mainly targets cysteine desulfurase, which is required for Fe-S cluster biosynthesis [40].…”

Iron–sulfur cluster assembly scaffold protein IscU is required for activation of ferric uptake regulator (Fur) in Escherichia coli

“…Additional studies have revealed that binding of the [2Fe-2S] cluster in Fur turns on its binding activity for the Fur-box ( 24 ). Furthermore, binding of the [2Fe-2S] cluster in Fur is highly conserved, as Fur proteins from Haemophilus influenzae , V. cholerae , and H. pylori also bind a [2Fe-2S] cluster in E. coli cells with an elevated intracellular free iron content ( 27 ). The results suggest that E. coli Fur binds a [2Fe-2S] cluster in response to elevation of intracellular free iron content and regulates intracellular iron homeostasis ( 24 , 25 , 26 ).…”