title: Tripeptidase gene (pepT) of Lactococcus lactis: molecular cloning and nucleotide sequencing of pepT and construction of a chromosomal deletion mutant.
abstract: The gene encoding a tripeptidase (pepT) of Lactococcus lactis subsp. cremoris (formerly subsp. lactis) MG1363 was cloned from a genomic library in pUC19 and subsequently sequenced. The tripeptidase of L. lactis was shown to be homologous to PepT of Salmonella typhimurium with 47.4% identity in the deduced amino acid sequences. L. lactis PepT was enzymatically active in Escherichia coli and allowed growth of a peptidase-negative leucine-auxotrophic E. coli strain by liberation of Leu from a tripeptide. Using a two-step integration-excision system, a pepT-negative mutant of L. lactis was constructed. No differences between the growth of the mutant and that of the wild-type strain in milk or in chemically defined medium with casein as the sole source of essential amino acids were observed.
authors.affiliation: Department of Genetics, University of Groningen, Haren, The Netherlands.
authors.forename: I
authors.initials: I
authors.lastname: Mierau
authors.forename: A J
authors.initials: AJ
authors.lastname: Haandrikman
authors.forename: O
authors.initials: O
authors.lastname: Velterop
authors.forename: P S
authors.initials: PS
authors.lastname: Tan
authors.forename: K L
authors.initials: KL
authors.lastname: Leenhouts
authors.forename: W N
authors.initials: WN
authors.lastname: Konings
authors.forename: G
authors.initials: G
authors.lastname: Venema
authors.forename: J
authors.initials: J
authors.lastname: Kok
mesh_terms: D000595:Amino Acid Sequence; D000626:Aminopeptidases; D001483:Base Sequence; D015152:Blotting, Northern; D015139:Blotting, Southern; D002876:Chromosomes, Bacterial; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics; D005798:Genes, Bacterial / Q000235:genetics*; D013294:Lactococcus lactis / Q000201:enzymology / Q000235:genetics*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010447:Peptide Hydrolases / Q000096:biosynthesis / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000096:biosynthesis; D012486:Salmonella typhimurium / Q000235:genetics; D017422:Sequence Analysis, DNA; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid
chemical_list: D011994:Recombinant Proteins; D010447:Peptide Hydrolases; D000626:Aminopeptidases; C023191:PepT tripeptidase