title: Effect of vancomycin on the proteome of the multiresistant Enterococcus faecium SU18 strain.
abstract: Enterococci are not highly pathogenic bacteria, but the incidence of vancomycin resistance among clinical isolates of this microbial group is steadily increasing, posing a threat to public health. Vancomycin-resistant enterococci are currently some of the most recalcitrant hospital-associated pathogens against which new therapies are urgently needed. To understand the molecular mechanisms of bacterial resistance to glycopeptides, we obtained proteomic profiles of the vancomycin-resistant Enterococcus faecium SU18 strain treated with and without vancomycin. Fourteen proteins were differentially expressed in SU18, seven of which were up-regulated and seven down-regulated. Proteins involved in the vancomycin resistance mechanism, such as the VanA protein, VanA ligase, VanR and D-Ala-D-Ala dipeptidase, were up-regulated in the presence of vancomycin, while metabolism-related proteins, such as triosephosphate isomerase, guanine monophosphate synthase and glyceraldehyde-3-phosphate dehydrogenase were down-regulated. Overall the compensatory response of SU18 to antibiotics is to alter expression of proteins related to antibiotic resistance, cell wall formation and energy metabolism. Some of the differentially expressed proteins might enhance antimicrobial activity and are now being investigated as potential therapeutic drug targets in other pathogenic bacteria.
  
  
  CONCLUSIONS
  This study highlights the power of proteomics in the study of differential protein expression in a multiresistant Enterococcus faecium strain when subjected to vancomycin stress.
authors.affiliation: Institute for Biotechnology and Bioengineering, Centre for Genomics and Biotechnology, University of Trás-os-Montes and Alto Douro, Vila Real, Portugal; Department of Genetics and Biotechnology, University of Trás-os-Montes and Alto Douro, Vila Real, Portugal; Centre for Animal and Veterinary Science, University of Trás-os-Montes and Alto Douro, Vila Real, Portugal; Department of Veterinary Science, University of Trás-os-Montes and Alto Douro, Vila Real, Portugal.
authors.forename: Sónia
authors.initials: S
authors.lastname: Ramos
authors.affiliation: INRA (Institut National de la Recherche Agronomique), UR454 Microbiologie, Centre de Recherche de Clermont-Ferrand, F-63122 Saint-Genès Champanelle, France.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Chafsey
authors.affiliation: Centre for Animal and Veterinary Science, University of Trás-os-Montes and Alto Douro, Vila Real, Portugal.
authors.forename: Nuno
authors.initials: N
authors.lastname: Silva
authors.affiliation: INRA (Institut National de la Recherche Agronomique), UR454 Microbiologie, Centre de Recherche de Clermont-Ferrand, F-63122 Saint-Genès Champanelle, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Hébraud
authors.affiliation: Institute for Biotechnology and Bioengineering, Centre for Genomics and Biotechnology, University of Trás-os-Montes and Alto Douro, Vila Real, Portugal; Bioscope Group, Department of Chemistry, Faculty of Science and Technology, Nova de Lisboa University, Caparica, Portugal.
authors.forename: Hugo
authors.initials: H
authors.lastname: Santos
authors.affiliation: REQUIMTE, Department of Chemistry, Faculty of Technology and Science, University Nova de Lisboa, Caparica, Portugal; Bioscope Group, Department of Chemistry, Faculty of Science and Technology, Nova de Lisboa University, Caparica, Portugal.
authors.forename: José-Luis
authors.initials: JL
authors.lastname: Capelo-Martinez
authors.affiliation: Centre for Animal and Veterinary Science, University of Trás-os-Montes and Alto Douro, Vila Real, Portugal; Department of Veterinary Science, University of Trás-os-Montes and Alto Douro, Vila Real, Portugal.
authors.forename: Patrícia
authors.initials: P
authors.lastname: Poeta
authors.affiliation: Institute for Biotechnology and Bioengineering, Centre for Genomics and Biotechnology, University of Trás-os-Montes and Alto Douro, Vila Real, Portugal; Department of Genetics and Biotechnology, University of Trás-os-Montes and Alto Douro, Vila Real, Portugal. Electronic address: gigrejas@utad.pt.
authors.forename: Gilberto
authors.initials: G
authors.lastname: Igrejas
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial / Q000187:drug effects* / Q000235:genetics; D016984:Enterococcus faecium / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects* / Q000235:genetics; D020543:Proteome / Q000096:biosynthesis* / Q000235:genetics; D014640:Vancomycin / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D020543:Proteome; D014640:Vancomycin
keywords: Antibiotic resistance; Enterococcus faecium; Proteomic; Vancomycin-resistant enterococci