Part of the ABC transporter DppABCDF involved in the uptake of various di/tripeptides (PubMed:25338022). Prefers dipeptides with acidic residues at the C-terminal end. Involved in the uptake of phaseolotoxin, a toxic tripeptide inhibiting the enzyme ornithine carbamoyltransferase (PubMed:25338022). The complex is composed of two ATP-binding proteins (DppD and DppF), two transmembrane proteins (DppB and DppC) and a solute-binding protein (DppA1) (PubMed:25338022). Five orthologous SBPs (DppA1-A5) are present in P.aeruginosa, which increases the substrate specificity of the DppBCDF transporter (PubMed:25338022). Belongs to the bacterial solute-binding protein 5 family.