Part of the ABC transporter DppABCDF involved in the uptake of various di/tripeptides. The complex is composed of two ATP-binding proteins (DppD and DppF), two transmembrane proteins (DppB and DppC) and a solute-binding protein (DppA5) (Probable). Five orthologous SBPs (DppA1-A5) are present in P.aeruginosa, which increases the substrate specificity of the DppBCDF transporter (PubMed:25338022). DppA5 was not able to complement the DppA1-A5 penta mutant during high-throughput screening. Belongs to the bacterial solute-binding protein 5 family.