Bacillus subtilis copper-sensitive operon repressor (BsCsoR), and related domains; this family was previously known as part of DUF156
This domain family includes Bacillus subtilis CsoR (BsCsoR). CsoRs are Cu(I)-inducible, and regulate the expression of genes involved in copper homeostasis. BsCsoR regulates the copZA operon which encodes the copper chaperone CopZ, and the copper efflux P-type ATPase CopA. 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), Thermus thermophilus CsoR, and Staphylococcus aureus CsoR. The latter three proteins do not belong to this family. CsoRs regulate the expression of genes involved in copper homeostasis. 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 the 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: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.",