title: Reactive Oxygen Species Contribute to the Bactericidal Effects of the Fluoroquinolone Moxifloxacin in Streptococcus pneumoniae.
abstract: We studied the transcriptomic response of Streptococcus pneumoniae to the fluoroquinolone moxifloxacin at a concentration that inhibits DNA gyrase. Treatment of the wild-type strain R6, at a concentration of 10× the MIC, triggered a response involving 132 genes after 30 min of treatment. Genes from several metabolic pathways involved in the production of pyruvate were upregulated. These included 3 glycolytic enzymes, which ultimately convert fructose 6-phosphate to pyruvate, and 2 enzymes that funnel phosphate sugars into the glycolytic pathway. In addition, acetyl coenzyme A (acetyl-CoA) carboxylase was downregulated, likely leading to an increase in acetyl-CoA. When coupled with an upregulation in formate acetyltransferase, an increase in acetyl-CoA would raise the production of pyruvate. Since pyruvate is converted by pyruvate oxidase (SpxB) into hydrogen peroxide (H2O2), an increase in pyruvate would augment intracellular H2O2. Here, we confirm a 21-fold increase in the production of H2O2 and a 55-fold increase in the amount of hydroxyl radical in cultures treated during 4 h with moxifloxacin. This increase in hydroxyl radical through the Fenton reaction would damage DNA, lipids, and proteins. These reactive oxygen species contributed to the lethality of the drug, a conclusion supported by the observed protective effects of an SpxB deletion. These results support the model whereby fluoroquinolones cause redox alterations. The transcriptional response of S. pneumoniae to moxifloxacin is compared with the response to levofloxacin, an inhibitor of topoisomerase IV. Levofloxacin triggers the transcriptional activation of iron transport genes and also enhances the Fenton reaction.
authors.affiliation: Unidad de Genética Bacteriana, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: M J
authors.initials: MJ
authors.lastname: Ferrándiz
authors.affiliation: Unidad de Genética Bacteriana, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: A J
authors.initials: AJ
authors.lastname: Martín-Galiano
authors.affiliation: Unidad de Genética Bacteriana, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: C
authors.initials: C
authors.lastname: Arnanz
authors.affiliation: Unidad de Genética Bacteriana, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: T
authors.initials: T
authors.lastname: Zimmerman
authors.affiliation: Unidad de Genética Bacteriana, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Madrid, Spain Presidencia. Consejo Superior de Investigaciones Científicas, Madrid, Spain agcampa@isciii.es.
authors.forename: A G
authors.initials: AG
authors.lastname: de la Campa
mesh_terms: D000103:Acetyl-CoA Carboxylase / Q000235:genetics / Q000378:metabolism; D000123:Acetyltransferases / Q000235:genetics / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D027101:DNA Topoisomerase IV / Q000235:genetics / Q000378:metabolism; D024901:Drug Resistance, Multiple, Bacterial; D024841:Fluoroquinolones / Q000494:pharmacology*; D005636:Fructosephosphates / Q000378:metabolism; D017353:Gene Deletion; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D063990:Gene Ontology; D006019:Glycolysis / Q000187:drug effects / Q000235:genetics; D006861:Hydrogen Peroxide / Q000378:metabolism*; D007501:Iron / Q000378:metabolism; D064704:Levofloxacin / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D058977:Molecular Sequence Annotation; D000077266:Moxifloxacin; D018384:Oxidative Stress / Q000187:drug effects; D011771:Pyruvate Oxidase / Q000235:genetics / Q000378:metabolism; D019289:Pyruvic Acid / Q000378:metabolism; D013296:Streptococcus pneumoniae / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D024841:Fluoroquinolones; D005636:Fructosephosphates; C027618:fructose-6-phosphate; D064704:Levofloxacin; D019289:Pyruvic Acid; D006861:Hydrogen Peroxide; D007501:Iron; D011771:Pyruvate Oxidase; D000123:Acetyltransferases; C022560:formate C-acetyltransferase; D027101:DNA Topoisomerase IV; D000103:Acetyl-CoA Carboxylase; D000077266:Moxifloxacin