title: Cloning and functional expression in Escherichia coli of the gene encoding the di- and tripeptide transport protein of Lactobacillus helveticus.
abstract: The gene encoding the di- and tripeptide transport protein (DtpT) of Lactobacillus helveticus (DtpTLH) was cloned with the aid of the inverse PCR technique and used to complement the dipeptide transport-deficient and proline-auxotrophic Escherichia coli E1772. Functional expression of the peptide transporter was shown by the uptake of prolyl-[14C] alanine in whole cells and membrane vesicles. Peptide transport via DtpT in membrane vesicles is driven by the proton motive force. The system has specificity for di- and tripeptides but not for amino acids or tetrapeptides. The dtpTLH gene consists of 1,491 bp, which translates into a 497-amino-acid polypeptide. DtpTLH shows 34% identity to the di- and tripeptide transport protein of Lactococcus lactis and is also homologous to various peptide transporters of eukaryotic origin, but the similarity between these proteins is confined mainly to the N-terminal halves.
authors.affiliation: Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Haren, The Netherlands. ce9h-nkjm@asahi-net.or.jp
authors.forename: H
authors.initials: H
authors.lastname: Nakajima
authors.forename: A
authors.initials: A
authors.lastname: Hagting
authors.forename: E R
authors.initials: ER
authors.lastname: Kunji
authors.forename: B
authors.initials: B
authors.lastname: Poolman
authors.forename: W N
authors.initials: WN
authors.lastname: Konings
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D001693:Biological Transport, Active; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000235:genetics; D004151:Dipeptides / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression; D005798:Genes, Bacterial; D007700:Kinetics; D007778:Lactobacillus / Q000235:genetics* / Q000378:metabolism; D026901:Membrane Transport Proteins; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D004269:DNA, Bacterial; D004151:Dipeptides; D026901:Membrane Transport Proteins; D009842:Oligopeptides; C086845:dtpT protein, Lactococcus lactis