Antibacterial activities and characterization of novel inhibitors of LpxC.
Lipid A is the hydrophobic anchor of lipopolysaccharide (LPS) and forms the major lipid component of the outer monolayer of the outer membrane of gram-negative bacteria. Lipid A is required for bacterial growth and virulence, and inhibition of its biosynthesis is lethal to bacteria. UDP-3-O-(R-3-hydroxymyristoyl)-N-acetylglucosamine deacetylase (LpxC) is a metalloenzyme that catalyzes the second step in the biosynthesis of lipid A. Inhibitors of LpxC have previously been shown to have antibiotic activities. We have screened a metalloenzyme inhibitor library for antibacterial activities against an Escherichia coli strain with reduced LpxC activity. From this screen, a series of sulfonamide derivatives of the alpha-(R)-amino hydroxamic acids, exemplified by BB-78484 and BB-78485, have been identified as having potent inhibitory activities against LpxC in an in vitro assay. Leads from this series showed gram-negative selective activities against members of the Enterobacteriaceae, Serratia marcescens, Morganella morganii, Haemophilus influenzae, Moraxella catarrhalis, and Burkholderia cepacia. BB-78484 was bactericidal against E. coli, achieving 3-log killing in 4 h at a concentration 4 times above the MIC, as would be predicted for an inhibitor of lipid A biosynthesis. E. coli mutants with decreased susceptibility to BB-78484 were selected. Analysis of these mutants revealed that resistance arose as a consequence of mutations in the fabZ or lpxC genes. These data confirm the antibacterial target of BB-78484 and BB-78485 and validate LpxC as a target for gram-negative selective antibacterials.
Clements
John M
JM
British Biotech Pharmaceuticals Ltd., Oxford OX4 6LY, United Kingdom. clements@britbio.co.uk
Coignard
Fanny
F
Johnson
Ian
I
Chandler
Stephen
S
Palan
Shilpa
S
Waller
Andrew
A
Wijkmans
Jac
J
Hunter
Michael G
MG
D000581:Amidohydrolases / Q000037:antagonists & inhibitors* / Q000235:genetics; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D004274:DNA, Recombinant / Q000235:genetics; D004352:Drug Resistance, Microbial; D004357:Drug Synergism; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D004926:Escherichia coli / Q000235:genetics; D005838:Genotype; D006836:Hydro-Lyases / Q000235:genetics; D008826:Microbial Sensitivity Tests; D009154:Mutation / Q000235:genetics; D009281:Naphthalenes / Q000494:pharmacology*; D010957:Plasmids / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013449:Sulfonamides / Q000494:pharmacology*; D013997:Time Factors
D000900:Anti-Bacterial Agents; C466662:BB-78484; C466661:BB-78485; D004274:DNA, Recombinant; D004791:Enzyme Inhibitors; D009281:Naphthalenes; D013449:Sulfonamides; D000581:Amidohydrolases; C097307:UDP-3-O-acyl-N-acetylglucosamine deacetylase; D006836:Hydro-Lyases; C036180:beta-hydroxyacyl-(acyl-carrier-protein)dehydrase