Effect of fluoroquinolone exposure on the proteome of Salmonella enterica serovar Typhimurium.
OBJECTIVE
The physiological response of Salmonella enterica serovar Typhimurium to fluoroquinolone antibiotics was investigated using proteomic methods.


METHODS
Proteomes were prepared from strain SL1344 following treatment of broth cultures with ciprofloxacin (0.03 and 0.008 mg/L; 2x and 0.5x MIC) and enrofloxacin (0.03 mg/L) and from a multiple antibiotic resistant (MAR) mutant. Protein expression was determined by two-dimensional HPLC-MS(n) and also after exposure to ciprofloxacin by two-dimensional gel electrophoresis (2D-GE).


RESULTS
The number of proteins (mean +/- SD) detected by 2D-GE derived from control cultures of the wild-type strain was significantly (P < 0.05) reduced from 296 +/- 77 to 153 +/- 36 following treatment with ciprofloxacin (0.03 mg/L). Raised expression (P < 0.05) of 17 proteins was also detected, and increases of up to 8-fold (P < 0.0001) were observed for subunits of F1F0-ATP synthase, TolC and Imp. Analysis by two-dimensional HPLC-MS(n) provided higher proteome coverage with 787 +/- 50 proteins detected, which was reduced (P < 0.005) to 560 +/- 14 by ciprofloxacin (0.03 mg/L). Increased expression of 43 proteins was observed which included those detected by 2D-GE and additionally the efflux pump protein AcrB. The basal expression of the AcrAB/TolC efflux pump was elevated in the MAR mutant compared with the untreated wild-type and augmented following treatment with ciprofloxacin (0.03 mg/L). F1F0-ATP synthase and Imp were only elevated in the mutant when treated with ciprofloxacin.


CONCLUSIONS
These studies suggest that increased expression of AcrAB/TolC was associated with resistance while other increases, such as in F1F0-ATP synthase and Imp, were a response to fluoroquinolone.
Coldham
Nick G
NG
Department of Food and Environmental Safety, Veterinary Laboratories Agency, Addlestone, Surrey, KT15 3NB, UK. n.g.coldham@vla.defra.gsi.gov.uk
Randall
Luke P
LP
Piddock
Laura J V
LJ
Woodward
Martin J
MJ
D000222:Adaptation, Physiological; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001425:Bacterial Outer Membrane Proteins / Q000096:biosynthesis; D001426:Bacterial Proteins / Q000032:analysis* / Q000096:biosynthesis; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D002939:Ciprofloxacin / Q000494:pharmacology; D024901:Drug Resistance, Multiple, Bacterial; D015180:Electrophoresis, Gel, Two-Dimensional; D000077422:Enrofloxacin; D024841:Fluoroquinolones / Q000494:pharmacology*; D026901:Membrane Transport Proteins / Q000096:biosynthesis; D025261:Mitochondrial Proton-Translocating ATPases / Q000096:biosynthesis; D020543:Proteome / Q000187:drug effects*; D012486:Salmonella typhimurium / Q000187:drug effects* / Q000502:physiology
C474926:AcrB protein, Salmonella enterica; D000900:Anti-Bacterial Agents; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D024841:Fluoroquinolones; D026901:Membrane Transport Proteins; D020543:Proteome; D000077422:Enrofloxacin; D002939:Ciprofloxacin; C474451:F1F0-ATP synthase; D025261:Mitochondrial Proton-Translocating ATPases