Genetic and biochemical characterization of the oligopeptide transport system of Lactococcus lactis.

TitleGenetic and biochemical characterization of the oligopeptide transport system of Lactococcus lactis.
Publication TypeJournal Article
Year of Publication1993
AuthorsTynkkynen, S, Buist, G, Kunji, ERS, Kok, J, Poolman, B, Venema, G, Haandrikman, A
JournalJ Bacteriol
Volume175
Issue23
Pagination7523-32
Date Published1993 Dec
ISSN0021-9193
KeywordsAmino Acid Sequence, Amino Acids, Animals, Bacterial Proteins, Base Sequence, Biological Transport, Carrier Proteins, Genes, Bacterial, Glycolysis, Lactococcus lactis, Lipoproteins, Metalloendopeptidases, Milk, Molecular Sequence Data, Mutagenesis, Insertional, Oligopeptides, Plasmids, Sequence Analysis, DNA, Sequence Homology, Amino Acid
Abstract

The nucleotide sequence of a chromosomal DNA fragment of Lactococcus lactis subsp. lactis SSL135, previously implicated in peptide utilization, has been determined. The genes oppDFBCA, encoding the oligopeptide transport system (Opp), and that encoding the endopeptidase PepO were located on this 8.9-kb DNA fragment. The oppDFBCA and pepO genes are probably organized in an operon. Analysis of the deduced amino acid sequences of the genes indicated that the oligopeptide transport system consists of two ATP-binding proteins OppD and OppF, two integral membrane proteins OppB and OppC, and a substrate-binding protein OppA. On the basis of the homology of OppF and OppD of L. lactis with other ABC (ATP-binding cassette) transporter proteins, the L. lactis Opp system can be classified as a member of this group. Two integration mutants, one defective in OppA and the other defective in PepO, were constructed. Growth of these mutants in a chemically defined medium with oligopeptides showed that the transport system, but not the endopeptidase, is essential for the utilization of peptides longer than three residues. Uptake of the pentapeptide Leu-enkephalin in glycolyzing lactococcal cells was followed by rapid hydrolysis of the peptide intracellularly. Importantly, extracellular hydrolysis of Leu-enkephalin is not observed. The OppA-deficient mutant was unable to transport Leu-enkephalin. Growth experiments with pasteurized milk revealed that transport of oligopeptides forms an essential part of the proteolytic system in lactococci.

DOI10.1128/jb.175.23.7523-7532.1993
Alternate JournalJ. Bacteriol.
Citation Key10.1128/jb.175.23.7523-7532.1993
PubMed ID8244921
PubMed Central IDPMC206908