Biophysical characterization of the proton-coupled oligopeptide transporter YjdL

► Direct binding of dipeptide ligands to the purified peptide transporter YjdL has been established. ► Binding of Ala-Lys can be detected whereas Ala-Gln, which has similar potency, is undetectable. ► Binding is undetectable to a Gln-variant of the highly conserved Glu388.