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  • Iron-sulfur cluster assembly scaffold protein IscU is required for activation of ferric uptake regulator (Fur) in Escherichia coli
Title: Iron-sulfur cluster assembly scaffold protein IscU is required for activation of ferric uptake regulator (Fur) in Escherichia coli
It was previously postulated that when intracellular free iron content is elevated in bacteria, the Ferric uptake regulator (Fur) binds its co-repressor a mononuclear ferrous iron to regulate intracellular iron homeostasis. However, the proposed iron-bound Fur had not been identified in any bacteria. In previous studies, we have demonstrated that Escherichia coli Fur binds a [2Fe-2S] cluster in response to elevation of intracellular free iron content, and that binding of the [2Fe-2S] cluster turns on Fur as an active repressor to bind a specific DNA sequence known as the Fur-box. Here we find that the iron-sulfur cluster assembly scaffold protein IscU is required for the [2Fe-2S] cluster assembly in Fur, as deletion of IscU inhibits the [2Fe-2S] cluster assembly in Fur and prevents activation of Fur as a repressor in E. coli cells in response to elevation of intracellular free iron content. Additional studies reveal that IscU promotes the [2Fe-2S] cluster assembly in apo-form Fur and restores its Fur-box binding activity in vitro. While IscU is also required for the [2Fe-2S] cluster assembly in the Haemophilus influenzae Fur in E. coli cells, deletion of IscU does not significantly affect the [2Fe-2S] cluster assembly in the E. coli ferredoxin and siderophore-reductase FhuF. Our results suggest that IscU may have a unique role for the [2Fe-2S] cluster assembly in Fur, and that regulation of intracellular iron homeostasis is closely coupled with iron-sulfur cluster biogenesis in E. coli.  more » « less
Award ID(s):
2050032
PAR ID:
10495554
Author(s) / Creator(s):
; ;
Publisher / Repository:
Elsevier
Date Published:
Journal Name:
Journal of Biological Chemistry
ISSN:
0021-9258
Page Range / eLocation ID:
107142
Subject(s) / Keyword(s):
Iron homeostasis, iron-sulfur cluster biogenesis, ferric uptake regulator (Fur).
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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