title: Cytotoxic Effect Associated with Overexpression of QNR Proteins in Escherichia coli.
abstract: OBJECTIVE
  The objective was to evaluate the cytotoxic effect associated with overexpression of multiple Qnr-like plasmid-mediated quinolone resistance (PMQR) mechanisms in Escherichia coli.
  
  
  METHODS
  Coding regions of different PMQR genes (qnrA1, qnrB1, qnrC, qnrD1, qnrS1, and qepA2) and efsqnr were cloned into pET29a(+) vector and overexpressed in E. coli BL21. E. coli BL21 with and without an empty pET29a(+) vector were used as controls. The cytotoxic effect associated with PMQR mechanism overexpression was determined by transmission electron microscopy and viability assays.
  
  
  RESULTS
  Overexpressed qnr genes produced loss of bacterial viability in the range of 77-97% compared with the controls, comparable with loss of viability associated with EfsQnr overexpression (97%). No loss of viability was observed in E. coli overexpressing QepA2. In transmission electron microscopy assays, signs of cytotoxicity were observed in E. coli cells overexpressing EfsQnr and Qnr proteins (30-45% of the bacterial population showed morphological changes). Morphological changes were observed in less than 5% of bacterial populations from the control strains and E. coli overexpressing QepA2.
  
  
  CONCLUSIONS
  Overexpression of qnr genes produces a cytotoxic cellular and structural effect in E. coli, the magnitude of which varies depending on the family of Qnr proteins.
authors.affiliation: 1 Unidad Intercentros de Enfermedades Infecciosas, Microbiología y Medicina Preventiva, Hospital Universitario Virgen Macarena , Seville, Spain .|2 Institute of Biomedicine of Seville (IBiS) , Seville, Spain .
authors.forename: Jesús
authors.initials: J
authors.lastname: Machuca
authors.affiliation: 1 Unidad Intercentros de Enfermedades Infecciosas, Microbiología y Medicina Preventiva, Hospital Universitario Virgen Macarena , Seville, Spain .
authors.forename: Paula
authors.initials: P
authors.lastname: Diaz de Alba
authors.affiliation: 1 Unidad Intercentros de Enfermedades Infecciosas, Microbiología y Medicina Preventiva, Hospital Universitario Virgen Macarena , Seville, Spain .
authors.forename: Esther
authors.initials: E
authors.lastname: Recacha
authors.affiliation: 1 Unidad Intercentros de Enfermedades Infecciosas, Microbiología y Medicina Preventiva, Hospital Universitario Virgen Macarena , Seville, Spain .|2 Institute of Biomedicine of Seville (IBiS) , Seville, Spain .|3 Department of Microbiology, University of Seville , Seville, Spain .
authors.forename: Álvaro
authors.initials: Á
authors.lastname: Pascual
authors.affiliation: 2 Institute of Biomedicine of Seville (IBiS) , Seville, Spain .|3 Department of Microbiology, University of Seville , Seville, Spain .
authors.forename: José Manuel
authors.initials: JM
authors.lastname: Rodriguez-Martinez
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism / Q000648:ultrastructure; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism / Q000633:toxicity; D015870:Gene Expression; D050296:Microbial Viability; D046529:Microscopy, Electron, Transmission; D009152:Mutagenicity Tests; D010957:Plasmids / Q000737:chemistry / Q000378:metabolism; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism / Q000633:toxicity; D015363:Quinolones / Q000494:pharmacology; D014169:Transformation, Bacterial
chemical_list: D000900:Anti-Bacterial Agents; D029968:Escherichia coli Proteins; D020033:Protein Isoforms; C485384:Qnr protein, E coli; D015363:Quinolones
keywords: E. coli; cytotoxic effect; qnr