Sensing iron availability <i>via</i> the fragile [4Fe-4S] cluster of the bacterial transcriptional repressor RirA.

ABSTRACT: Rhizobial iron regulator A (RirA) is a global regulator of iron homeostasis in many nitrogen-fixing Rhizobia and related species of α-proteobacteria. It belongs to the widespread Rrf2 super-family of transcriptional regulators and features three conserved Cys residues that characterise the binding of an iron-sulfur cluster in other Rrf2 family regulators. Here we report biophysical studies demonstrating that RirA contains a [4Fe-4S] cluster, and that this form of the protein binds RirA-regulated DNA, consistent with its function as a repressor of expression of many genes involved in iron uptake. Under low iron conditions, [4Fe-4S] RirA undergoes a cluster conversion reaction resulting in a [2Fe-2S] form, which exhibits much lower affinity for DNA. Under prolonged low iron conditions, the [

SUBMITTER: Pellicer Martinez MT 

PROVIDER: S-EPMC5863699 | biostudies-literature | 2017 Dec

REPOSITORIES: biostudies-literature