Alcaligenes xylosoxidans NreA and related domains; this domain family was previously known as part of DUF156
This domain family includes Alcaligenes xylosoxidans NreA, Psudomonas putida MreA, and related domains. The gene encoding Alcaligenes xylosoxidans NreA is part of the nre nickel resistance locus located on the pTOM9 plasmid from this bacteria; it confers low-level nickel resistance on both Ralstonia and Escherichia coli strains. The Pseudomonas putida MreA gene is found in association with a gene encoding mrdH, a heavy metal efflux transporter of broad specificity. MreA may have a role in cadmium and nickel resistance. 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 members of this family; however, a conserved Tyr and a Glu residue that facilitates allosteric regulation of DNA binding for CsoRs are poorly 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.",