5n07
From Proteopedia
Structure of the [4Fe-4S] form of the NO response regulator NsrR
Structural highlights
FunctionNSRR_STRCO Binds DNA; this binding is disrupted by nitrosylation upon exposure to nitric oxide (NO) and also by EDTA and iron chelators. The 2Fe-2S cluster is stable in the presence of O(2). Publication Abstract from PubMedNsrR from Streptomyces coelicolor (Sc) regulates the expression of three genes through the progressive degradation of its [4Fe-4S] cluster on nitric oxide (NO) exposure. We report the 1.95 A resolution crystal structure of dimeric holo-ScNsrR and show that the cluster is coordinated by the three invariant Cys residues from one monomer and, unexpectedly, Asp8 from the other. A cavity map suggests that NO displaces Asp8 as a cluster ligand and, while D8A and D8C variants remain NO sensitive, DNA binding is affected. A structural comparison of holo-ScNsrR with an apo-IscR-DNA complex shows that the [4Fe-4S] cluster stabilizes a turn between ScNsrR Cys93 and Cys99 properly oriented to interact with the DNA backbone. In addition, an apo ScNsrR structure suggests that Asn97 from this turn, along with Arg12, which forms a salt-bridge with Asp8, are instrumental in modulating the position of the DNA recognition helix region relative to its major groove. Crystal structures of the NO sensor NsrR reveal how its iron-sulfur cluster modulates DNA binding.,Volbeda A, Dodd EL, Darnault C, Crack JC, Renoux O, Hutchings MI, Le Brun NE, Fontecilla-Camps JC Nat Commun. 2017 Apr 20;8:15052. doi: 10.1038/ncomms15052. PMID:28425466[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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