DmpK is an auxiliary protein associated with the multicomponent phenol hydroxylase DmpLMNOP and it may be involved in the post-translational incorporation of iron into the oxygenase component of the phenol hydroxylase (PubMed:8995386). Required for growth on phenol but not for in vitro phenol hydroxylase activity (PubMed:2254258, PubMed:2254259). Aromatic compound metabolism; phenol degradation. Homotrimer or homotetramer (PubMed:8995386). Interacts with the phenol hydroxylase components DmpL (P1 component) and DmpN (P3 component) (PubMed:8995386). Cells lacking this gene cannot grow on phenol.