Silver Binding to Bacterial Glutaredoxins Observed by NMR

Abstract

Glutaredoxins (GRXs) are a class of enzymes used in the reduction of protein thiols and the removal of reactive oxygen species. The CPYC active site of GRX is a plausible metal binding site, but was previously theorized not to bind metals due to its cis-proline configuration. We have shown that not only do several transition metals bind to the CPYC active site of the Brucella melitensis GRX but also report a model of a dimeric GRX in the presence of silver. This metal complex has also been characterized using enzymology, mass spectrometry, size exclusion chromatography, and molecular modeling. Metalation of GRX unwinds the end of the helix displaying the CPYC active site to accommodate dimerization in a way that is similar to iron sulfur cluster binding in related homologs and may imply that metal binding is a more common occurrence in this class of oxidoreductases than previously appreciated.

Zn(II) to Ag(I) Swap in Rad50 Zinc Hook Domain Leads to Interprotein Complex Disruption through the Formation of Highly Stable Agx(Cys)y Cores

“…Nevertheless, in structures where the Ag­(I)–thiolate bonding dominates, Ag­(Cys) 2 and Ag­(Cys) 3 coordination spheres are mostly formed, with the characteristic bond lengths of 2.40 and 2.49 Å, respectively . Structural examples of Ag­(I)–thiolate sites demonstrate the formation of mono- (PDB ID: 1Q06, 5NXL, 6XTL, 2MZC ) and multinuclear (PDB ID: 1AOO, 5F0W ) centers, localized either within a single polypeptide chain ,, or at protein interfaces. , Such diversity of binding architectures reflects the mentioned plasticity of Ag­(I)–thiolate sites, which enables them to accommodate different protein conformations and may also relate to the Ag­(I) binding strength.…”

“…26 Structural examples of Ag(I)−thiolate sites demonstrate the formation of mono-(PDB ID: 1Q06, 27 5NXL, 28 6XTL, 29 2MZC 30 ) and multinuclear (PDB ID: 1AOO, 31 5F0W 32 ) centers, localized either within a single polypeptide chain 27,28,31 or at protein interfaces. 30,32 Such diversity of binding architectures reflects the mentioned plasticity of Ag(I)−thiolate sites, which enables them to accommodate different protein conformations and may also relate to the Ag(I) binding strength.…”