title: A widespread picture of the Streptococcus thermophilus proteome by cell lysate fractionation and gel-based/gel-free approaches.
abstract: Among the group of lactic acid bacteria, Streptococcus thermophilus has found a wide application in industrial processes used for the manufacture of dairy products. Taking advantage of different proteome extraction and subfractionation protocols, bacterial cytosolic and membrane proteins were isolated and resolved by independent gel-free and gel-based separation procedures. Whole cytosolic fraction and its acid, basic and low molecular mass protein components were separated by different resolutive 2-DE and tricine 1-DE gels and identified by MALDI-TOF PMF and/or microLC-ESI-IT-MS/MS. Membrane proteins were resolved by 2-DE and SDS-PAGE gels and similarly identified by PMF and TMS analysis. In parallel, whole extract was trypsinized and resulting peptides were identified by shotgun 2-D LC-ESI-IT-MS/MS analysis. Using this combined approach, expression products corresponding to 458 different genes were identified, which cover almost a third of the predicted vegetative proteome. Relative protein concentration and hydrophobicity affected protein detection. Broad recognition was obtained for enzymes involved in carbohydrate, fatty acid, amino acid and nucleotide metabolism, replication, transcription, translation, cell wall synthesis, as well as for proteins affecting bacterial functions important for industrial applications, i.e. milk sugar import and exopolysaccharide biosynthesis. By providing detailed reference electrophoretic/chromatographic maps to be used in future comparative proteomic investigations on bacteria grown under various experimental conditions or on different bacterial strains, our results will favour dedicated studies on S. thermophilus metabolism and its regulation or on detection of biomarkers for selection of optimal strains for industrial applications.
authors.affiliation: Proteomics and Mass Spectrometry Laboratory, Istituto per il Sistema Produzione Animale in Ambiente Mediterraneo, National Research Council, Naples, Italy.
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Salzano
authors.forename: Simona
authors.initials: S
authors.lastname: Arena
authors.forename: Giovanni
authors.initials: G
authors.lastname: Renzone
authors.forename: Chiara
authors.initials: C
authors.lastname: D'Ambrosio
authors.forename: Rosario
authors.initials: R
authors.lastname: Rullo
authors.forename: Maurizio
authors.initials: M
authors.lastname: Bruschi
authors.forename: Luigi
authors.initials: L
authors.lastname: Ledda
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Maglione
authors.forename: Giovanni
authors.initials: G
authors.lastname: Candiano
authors.forename: Lino
authors.initials: L
authors.lastname: Ferrara
authors.forename: Andrea
authors.initials: A
authors.lastname: Scaloni
mesh_terms: D000595:Amino Acid Sequence; D001433:Bacteriolysis; D003600:Cytosol / Q000737:chemistry; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D008565:Membrane Proteins / Q000737:chemistry; D053858:Metabolic Networks and Pathways; D008969:Molecular Sequence Data; D020543:Proteome / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D048249:Streptococcus thermophilus / Q000737:chemistry*
chemical_list: D008565:Membrane Proteins; D020543:Proteome