title: Penicillin G increases the synthesis of a suicidal marker (CidC) and virulence (HlgBC) proteins in Staphylococcus aureus biofilm cells.
abstract: The present study reports the effect of Penicillin G (PenG) on the proteome dynamics of the Staphylococcus aureus strain Newman during biofilm mode of growth. The viability of the 18-h-old biofilm cells challenged with PenG at the concentration of 1mgmL(-1) was first assessed by plate counting, resazurin and LIVE/DEAD fluorescence staining, which indicated that the viability was reduced by ∼35% and ∼90% at 2h and 24h, respectively, after the addition of PenG. Subsequent two-dimensional difference gel electrophoresis (2D DIGE) assay of the treated and non-treated biofilm cells at the indicated time points revealed 45 proteins showing time- and treatment-specific change (1.5-fold, p<0.01). The 2D DIGE results suggested that the PenG-induced decrease in viability was accompanied by an increased synthesis of pyruvate oxidase (CidC), a suicidal marker known to potentiate acetate-dependent cell death in S. aureus. Increased abundance was also found for the TCA cycle associated malate-quinone oxidoreductase (Mqo), the ClpC ATPase, the HlgBC toxin and phage-associated proteins, which suggests that surviving cells have induced these activities as a last effort to overcome lethal doses of PenG. Proteomic results also revealed that the surviving cells were likely to strengthen their peptidoglycan due to the increased abundance of cell-wall biogenesis associated proteins, FemA and Pbp2; a phenomenon associated with dormancy in S. aureus.
authors.affiliation: Department of Food and Environmental Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Finland; Institute of Biotechnology, University of Helsinki, Finland; Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, Finland. Electronic address: kirsi.savijoki@helsinki.fi.
authors.forename: Kirsi
authors.initials: K
authors.lastname: Savijoki
authors.affiliation: Pharmaceutical Biology, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, Finland.
authors.forename: Malena
authors.initials: M
authors.lastname: Skogman
authors.affiliation: Pharmaceutical Biology, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, Finland.
authors.forename: Adyary
authors.initials: A
authors.lastname: Fallarero
authors.affiliation: Institute of Biotechnology, University of Helsinki, Finland.
authors.forename: Tuula A
authors.initials: TA
authors.lastname: Nyman
authors.affiliation: Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, Finland.
authors.forename: Antti
authors.initials: A
authors.lastname: Sukura
authors.affiliation: Pharmaceutical Biology, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, Finland.
authors.forename: Pia
authors.initials: P
authors.lastname: Vuorela
authors.affiliation: Department of Food and Environmental Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Finland.
authors.forename: Pekka
authors.initials: P
authors.lastname: Varmanen
mesh_terms: D000900:Anti-Bacterial Agents / Q000378:metabolism*; D001426:Bacterial Proteins / Q000096:biosynthesis*; D018441:Biofilms / Q000187:drug effects*; D015180:Electrophoresis, Gel, Two-Dimensional; D050296:Microbial Viability / Q000187:drug effects; D010400:Penicillin G / Q000378:metabolism*; D020543:Proteome / Q000032:analysis; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000502:physiology; D037521:Virulence Factors / Q000096:biosynthesis*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D020543:Proteome; D037521:Virulence Factors; D010400:Penicillin G
keywords: 2D DIGE; Biofilm; CidC; HlgBC; Penicillin G; Staphylococcus aureus