Affiliation:
1. Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9751 NN Haren, The Netherlands
Abstract
ABSTRACT
The peptide transport protein DtpT of
Lactococcus lactis
was purified and reconstituted into detergent-destabilized liposomes. The kinetics and substrate specificity of the transporter in the proteoliposomal system were determined, using Pro-[
14
C]Ala as a reporter peptide in the presence of various peptides or peptide mimetics. The DtpT protein appears to be specific for di- and tripeptides, with the highest affinities for peptides with at least one hydrophobic residue. The effect of the hydrophobicity, size, or charge of the amino acid was different for the amino- and carboxyl-terminal positions of dipeptides. Free amino acids, ω-amino fatty acid compounds, or peptides with more than three amino acid residues do not interact with DtpT. For high-affinity interaction with DtpT, the peptides need to have free amino and carboxyl termini, amino acids in the
l
configuration, and
trans
-peptide bonds. Comparison of the specificity of DtpT with that of the eukaryotic homologues PepT
1
and PepT
2
shows that the bacterial transporter is more restrictive in its substrate recognition.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
36 articles.
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