Staphylococcus aureus copper-sensitive operon repressor (CsoR), and related domains; this family was previously known as part of DUF156
This domain family includes Staphylococcus aureus CsoR (SaCsoR). SaCsoR is Cu(I)-inducible, and regulates the expression of genes involved in copper homeostasis; it represses a genetically unlinked copA-copZ operon. copA encodes a copper efflux P-type ATPase, and copZ, a copper chaperone. This family belongs to a larger superfamily that contains various transcriptional regulators that respond to different stressors such as Cu(I), Ni(I), sulfite, and formaldehyde, and includes Mycobacterium tuberculosis CsoR (MtCsoR), Bacillus subtilis CsoR, and Thermus thermophilus CsoR. The latter three proteins do not belong to this family. CsoRs form homotetramers (dimer of dimers). In MtCsoR, within each dimer, two Cys residues on opposite subunits, along with a His residue, bind the Cu(I) ion (forming a triagonal S2N coordination complex, C-H-C). These residues are conserved in the majority of members of this superfamily, including this family, and a conserved Tyr and a Glu residue that facilitate allosteric regulation of DNA binding for CsoRs are also well conserved.
Feature 1:putative metal binding site [ion binding site]
Evidence:
Comment:based on the binding of another superfamily member (Mycobacterium tuberculosis CsoR/MtCsoR) to Cu(I)
Comment:not all members of this superfamily are responsive to metal ions
Comment:MtCsoR forms a homotetramer (dimer of dimers); each CsoR homodimer contains two symmetry-related subunit-bridging Cu(I) binding sites, one on either end. Each Cu(I) is coordinated by a Cys residue from one monomer, and a His and Cys residue from its partner monomer.
Jiyao W et al.(2023). "The conserved domain database in 2023.",