May have transcription regulation and metal-detoxifying functions through which it may enhance intracellular survival of mycobacteria. Binds to its own promoter region and to the Rv1999c promoter region. It displays strong affinity for cadmium ions, but can also bind zinc, manganese and nickel. Expression increases the intracellular survival of recombinant M. smegmatis in murine macrophage cell line and increases its tolerance to cadmium ions. Homodimer. Contains an N-terminal winged-helix-turn-helix (wHTH) DNA-binding domain and a C-terminal alpha helix, which is mainly involved in dimerization (PubMed:30266832). Binding of cadmium causes subtle conformational changes in all key metal-binding residues and conserved DNA-binding residues (PubMed:30266832).