title: The specificity of oligopeptide transport by Streptococcus thermophilus resembles that of Lactococcus lactis and not that of pathogenic streptococci.
abstract: Peptide transport is a crucial step in the growth of Streptococcus thermophilus in protein- or peptide-containing media. The objective of the present work was to determine the specificity of peptide utilization by this widely used lactic acid bacterium. To reach that goal, complementary approaches were employed. The capability of a proteinase-negative S. thermophilus strain to grow in a chemically defined medium containing a mixture of peptides isolated from milk as the source of amino acids was analysed. Peptides were separated into three size classes by ultrafiltration. The strain was able to use peptides up to 3.5 kDa during growth, as revealed by liquid chromatography and mass spectrometry analyses. The same strain was grown in chemically defined medium containing a tryptic digest of casein, and the respective time-course consumption of the peptides during growth was estimated. The ability to consume large peptides (up to 23 residues) was confirmed, as long as they are cationic and hydrophobic. These results were confirmed by peptide transport studies. Extension of the study to 11 other strains revealed that they all shared these preferences.
authors.affiliation: Unité de Biochimie et Structure des Protéines, Institut National de la Recherche Agronomique, Centre de Recherches de Jouy-en-Josas, 78352 Jouy-en-Josas Cedex, France.
authors.forename: Odile
authors.initials: O
authors.lastname: Juille
authors.affiliation: Unité de Biochimie et Structure des Protéines, Institut National de la Recherche Agronomique, Centre de Recherches de Jouy-en-Josas, 78352 Jouy-en-Josas Cedex, France.
authors.forename: Dominique Le
authors.initials: DL
authors.lastname: Bars
authors.affiliation: Useful Bacterial Surface Proteins, Unité de Recherches Laitières et Génétique Appliquée, Institut National de la Recherche Agronomique, Centre de Recherches de Jouy-en-Josas, 78352 Jouy-en-Josas Cedex, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Juillard
mesh_terms: D002364:Caseins / Q000378:metabolism; D013294:Lactococcus lactis / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000502:physiology*; D008894:Milk Proteins / Q000378:metabolism; D009842:Oligopeptides / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D010447:Peptide Hydrolases / Q000235:genetics; D048249:Streptococcus thermophilus / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D002364:Caseins; D026901:Membrane Transport Proteins; D008894:Milk Proteins; D009842:Oligopeptides; C475729:casein hydrolysate; C043912:peptide permease; D010447:Peptide Hydrolases