Thermus thermophilus CsoR, a Cu(I)-sensing transcriptional regulator, and related domains; this domain family was previously known as part of DUF156
This domain family contains various Cu(I)-inducible transcriptional regulators including CsoR (copper-sensitive operon repressor) from Mycobacterium tuberculosis (MtCsoR), and Thermus thermophilus (TthCsoR). CsoR regulates the expression of genes involved in copper homeostasis. For example, TthCsoR binds the promoter region of the copZ-csoR-copA operon, and represses expression of these genes, which encode the copper chaperone CopZ, CsoR, and the copper efflux P-type ATPase CopA, respectively. In the presence of excess Cu(I), TthCsoR binds this ion, and is released from the DNA, allowing expression of the downstream genes. TthCsoR also senses other metal ions such as Cu(II), Zn(II), Ag(I), Cd(II) and Ni(II). MtCsoR regulates an operon that includes CsoR and a putative copper transporter gene, ctpV (cation transporter P-type ATPase). CsoRs form a homotetramer (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 some but not all members of this family; for example, for TthCsoR, there is a His instead of the second Cys as well as an N-terminal His (not found in those family members having C-H-C) which may also be involved in metal binding (H-C-H-H). A conserved Tyr and a Glu residue facilitate allosteric regulation of DNA binding.
Feature 1:putative metal binding site [ion binding site]
Evidence:
Comment:based on binding of Mycobacterium tuberculosis CsoR to Cu(I)
Structure:2HH7; Mycobacterium tuberculosis CsoR binds Cu(I) in one of two copper binding sites; this is a partial binding site, the other Cys and His residue are contributed by the partner monomer of the homodimer
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. For TthCsoR, an N-terminal His residue may also be involved in metal-ion-binding.
Jiyao W et al.(2023). "The conserved domain database in 2023.",