Ligand binding analyses of the putative peptide transporter YjdL from E. coli display a significant selectivity towards dipeptides

Biochem Biophys Res Commun. 2009 Nov 6;389(1):112-6. doi: 10.1016/j.bbrc.2009.08.098. Epub 2009 Aug 22.


Proton-dependent oligopeptide transporters (POTs) are secondary active transporters that couple the inwards translocation of di- and tripeptides to inwards proton translocation. Escherichia coli contains four genes encoding the putative POT proteins YhiP, YdgR, YjdL and YbgH. We have over-expressed the previously uncharacterized YjdL and investigated the peptide specificity by means of uptake inhibition. The IC(50) value for the dipeptide Ala-Ala was measured to 22 mM while Ala-Ala-Ala was not able to inhibit uptake. In addition, IC(50) values of 0.3 mM and 1.5 mM were observed for Ala-Lys and Tyr-Ala, respectively, while the alanyl-extended tripeptides Ala-Lys-Ala, Ala-Ala-Lys, Ala-Tyr-Ala and Tyr-Ala-Ala displayed values of 8, >50, 31 and 31 mM, respectively. These results clearly indicate that unlike most POT members characterized to date, including YdgR and YhiP, YjdL shows significantly higher specificity towards dipeptides.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Coumarins / metabolism
  • Dipeptides / metabolism*
  • Escherichia coli / metabolism*
  • Escherichia coli Proteins / genetics
  • Escherichia coli Proteins / metabolism*
  • Ligands
  • Membrane Transport Proteins / genetics
  • Membrane Transport Proteins / metabolism*
  • Oligopeptides / metabolism


  • Coumarins
  • Dipeptides
  • Escherichia coli Proteins
  • Ligands
  • Membrane Transport Proteins
  • Oligopeptides
  • YjdL protein, E coli
  • alanyl-lysyl-amca