C-terminal domain of Faecalibacterium prausnitzii A2-165 FrmR , and related domains; this domain family was previously known as part of DUF156
This domain family contains the C-terminal domain of the functionally uncharacterized protein Faecalibacterium prausnitzii A2-165 FrmR, and related domains. This family is part of a larger superfamily that contains various transcriptional regulators that respond to different stressors such as Cu(I), Ni(I), sulfite, and formaldehyde, and includes CsoRs (copper-sensitive operon repressors). CsoRs form homotetramers (dimer of dimers). In Mycobacterium tuberculosis CsoR, 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 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.",