Organic and inorganic mercurials have distinct effects on cellular thiols, metal homeostasis, and Fe-binding proteins in Escherichia coli.

The protean chemical properties of the toxic metal mercury (Hg) have made it attractive in diverse applications since antiquity. However, growing public concern has led to an international agreement to decrease its impact on health and the environment. During a recent proteomics study of acute Hg exposure in E.

Dipeptide-based models of nickel superoxide dismutase: solvent effects highlight a critical role to Ni-S bonding and active site stabilization.

Nickel superoxide dismutase (Ni-SOD) catalyzes the disproportionation of the superoxide radical to O(2) and H(2)O(2) utilizing the Ni(III/II) redox couple. The Ni center in Ni-SOD resides in an unusual coordination environment that is distinct from other SODs. In the reduced state (Ni-SOD(red)), Ni(II) is ligated to a primary amine-N from His1, anionic carboxamido-N/thiolato-S from Cys2, and a second thiolato-S from Cys6 to complete a NiN(2)S(2) square-planar coordination motif.

Control of copper resistance and inorganic sulfur metabolism by paralogous regulators in Staphylococcus aureus.

All strains of Staphylococcus aureus encode a putative copper-sensitive operon repressor (CsoR) and one other CsoR-like protein of unknown function. We show here that NWMN_1991 encodes a bona fide Cu(I)-inducible CsoR of a genetically unlinked copA-copZ copper resistance operon in S. aureus strain Newman.

Unnatural amino acid substitution as a probe of the allosteric coupling pathway in a mycobacterial Cu(I) sensor.

The Cu(I) sensor Mycobacterium tuberculosis CsoR is a founding member of a new metalloregulatory protein family. Here we show that two "atom" substitutions of the Nepsilon2 face of a Cu(I) coordinating histidine-61 allosterically uncouple Cu(I) and DNA binding, with no effect on Cu(I) binding affinity and coordination structure. A model analogous to the allosteric switch mechanism in Staphylococcus aureus CzrA, a zinc sensor protein with a completely different fold, is proposed.

Molecular insights into the metal selectivity of the copper(I)-sensing repressor CsoR from Bacillus subtilis.

Bacillus subtilis CsoR (Bsu CsoR) is a copper-sensing transcriptional repressor that regulates the expression of the copZA operon encoding a copper chaperone and a Cu efflux P-type ATPase, respectively. Bsu CsoR is a homologue of Mycobacterium tuberculosis CsoR (Mtb CsoR), representative of a large Cu(I)-sensing regulatory protein family. We show here that Bsu CsoR binds approximately 1 mol equiv of Cu(I) per monomer in vitro with an affinity >or=10(21) M(-1).

SurR: a transcriptional activator and repressor controlling hydrogen and elemental sulphur metabolism in Pyrococcus furiosus.

This work describes the identification and characterization of SurR, Pyrococcus furiosus sulphur (S(0)) response regulator. SurR was captured from cell extract using promoter DNA of a hydrogenase operon that is downregulated in the primary response of P. furiosus to S(0), as revealed by DNA microarray experiments.