Part of the ABC transporter DppABCDF involved in dipeptide transport (PubMed:7536291). Responsible for energy coupling to the transport system (Probable). When a foreign outer membrane heme receptor is expressed in E.coli, DppABCDF can also transport heme and its precursor, 5-aminolevulinic acid (ALA), from the periplasm into the cytoplasm. a dipeptide(out) + ATP + H2O = a dipeptide(in) + ADP + H(+) + phosphate The complex is composed of two ATP-binding proteins (DppD and DppF), two transmembrane proteins (DppB and DppC) and a solute-binding protein (DppA) (PubMed:7536291, PubMed:16905647). MppA can replace DppA as binding protein for heme and ALA transport (PubMed:16905647). Inactivation of the gene abolishes use of heme as an iron source. Belongs to the ABC transporter superfamily.