Dual targeting of GyrB and ParE by a novel aminobenzimidazole class of antibacterial compounds.
A structure-guided drug design approach was used to optimize a novel series of aminobenzimidazoles that inhibit the essential ATPase activities of bacterial DNA gyrase and topoisomerase IV and that show potent activities against a variety of bacterial pathogens. Two such compounds, VRT-125853 and VRT-752586, were characterized for their target specificities and preferences in bacteria. In metabolite incorporation assays, VRT-125853 inhibited both DNA and RNA synthesis but had little effect on protein synthesis. Both compounds inhibited the maintenance of negative supercoils in plasmid DNA in Escherichia coli at the MIC. Sequencing of DNA corresponding to the GyrB and ParE ATP-binding regions in VRT-125853- and VRT-752586-resistant mutants revealed that their primary target in Staphylococcus aureus and Haemophilus influenzae was GyrB, whereas in Streptococcus pneumoniae it was ParE. In Enterococcus faecalis, the primary target of VRT-125853 was ParE, whereas for VRT-752586 it was GyrB. DNA transformation experiments with H. influenzae and S. aureus proved that the mutations observed in gyrB resulted in decreased susceptibilities to both compounds. Novobiocin resistance-conferring mutations in S. aureus, H. influenzae, and S. pneumoniae were found in gyrB, and these mutants showed little or no cross-resistance to VRT-125853 or VRT-752586 and vice versa. Furthermore, gyrB and parE double mutations increased the MICs of VRT-125853 and VRT-752586 significantly, providing evidence of dual targeting. Spontaneous frequencies of resistance to VRT-752586 were below detectable levels (<5.2x10(-10)) for wild-type E. faecalis but were significantly elevated for strains containing single and double target-based mutations, demonstrating that dual targeting confers low levels of resistance emergence and the maintenance of susceptibility in vitro.
Grossman
Trudy H
TH
Vertex Pharmaceuticals Incorporated, 130 Waverly Street, Cambridge, MA 02139, USA.
Bartels
Douglas J
DJ
Mullin
Steve
S
Gross
Christian H
CH
Parsons
Jonathan D
JD
Liao
Yusheng
Y
Grillot
Anne-Laure
AL
Stamos
Dean
D
Olson
Eric R
ER
Charifson
Paul S
PS
Mani
Nagraj
N
D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology; D001562:Benzimidazoles / Q000737:chemistry / Q000494:pharmacology; D027101:DNA Topoisomerase IV / Q000037:antagonists & inhibitors*; D015195:Drug Design; D004926:Escherichia coli; D008826:Microbial Sensitivity Tests; D009154:Mutation; D013211:Staphylococcus aureus; D013296:Streptococcus pneumoniae; D013329:Structure-Activity Relationship; D059005:Topoisomerase II Inhibitors; D014508:Urea / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D001562:Benzimidazoles; D059005:Topoisomerase II Inhibitors; C510778:VRT 125853; C510779:VRT 752586; D014508:Urea; D027101:DNA Topoisomerase IV