title: Inhibition of DNA gyrase and DNA topoisomerase IV of Staphylococcus aureus and Escherichia coli by aminocoumarin antibiotics.
abstract: OBJECTIVE
  Aminocoumarin antibiotics are potent inhibitors of bacterial DNA gyrase. We investigated the inhibitory and antibacterial activity of naturally occurring aminocoumarin antibiotics and six structural analogues (novclobiocins) against DNA gyrase and DNA topoisomerase IV from Escherichia coli and Staphylococcus aureus as well as the effect of potassium and sodium glutamate on the activity of these enzymes.
  
  
  METHODS
  The inhibitory concentrations of the aminocoumarins were determined in gyrase supercoiling assays and topoisomerase IV decatenation assays. Both subunits of S. aureus topoisomerase IV were purified as His-Tag proteins in E. coli. The MIC was tested in vivo for the control organisms E. coli ATCC 25922 and S. aureus ATCC 29213.
  
  
  RESULTS
  DNA gyrase is the primary target in vitro of all investigated aminocoumarins. With the exception of simocyclinone D8, all other aminocoumarins inhibited S. aureus gyrase on average 6-fold more effectively than E. coli gyrase. Potassium glutamate is essential for the activity of S. aureus gyrase and increases the sensitivity of E. coli gyrase to aminocoumarins ≥ 10-fold. The antibacterial activity of the tested compounds mirrored their relative activities against topoisomerases.
  
  
  CONCLUSIONS
  The study provides insights about the substituents that are important for the inhibitory activity of aminocoumarins against the target enzymes, which will facilitate the rational design of improved antibiotics.
authors.affiliation: Pharmaceutical Biology, Pharmaceutical Institute, University of Tübingen, Auf der Morgenstelle 8, 72076 Tübingen, Germany.
authors.forename: Silke
authors.initials: S
authors.lastname: Alt
authors.forename: Lesley A
authors.initials: LA
authors.lastname: Mitchenall
authors.forename: Anthony
authors.initials: A
authors.lastname: Maxwell
authors.forename: Lutz
authors.initials: L
authors.lastname: Heide
mesh_terms: D049933:Aminocoumarins / Q000737:chemistry / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000302:isolation & purification; D003001:Cloning, Molecular; D027081:DNA Gyrase / Q000235:genetics; D027101:DNA Topoisomerase IV / Q000037:antagonists & inhibitors* / Q000235:genetics; D004278:DNA, Superhelical / Q000737:chemistry; D004926:Escherichia coli / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics; D005971:Glutamates / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012970:Sodium Glutamate / Q000494:pharmacology; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics; D013329:Structure-Activity Relationship; D059005:Topoisomerase II Inhibitors; D059003:Topoisomerase Inhibitors / Q000494:pharmacology*
chemical_list: D049933:Aminocoumarins; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004278:DNA, Superhelical; D005971:Glutamates; D059005:Topoisomerase II Inhibitors; D059003:Topoisomerase Inhibitors; D027101:DNA Topoisomerase IV; D027081:DNA Gyrase; D012970:Sodium Glutamate