Uridine-based inhibitors as new leads for antibiotics targeting Escherichia coli LpxC.
The UDP-3-O-(R-3-hydroxyacyl)-N-acetylglucosamine deacetylase LpxC catalyzes the committed reaction of lipid A (endotoxin) biosynthesis in Gram-negative bacteria and is a validated antibiotic target. Although several previously described compounds bind to the unique acyl chain binding passage of LpxC with high affinity, strategies to target the enzyme's UDP-binding site have not been reported. Here the identification of a series of uridine-based LpxC inhibitors is presented. The most potent examined, 1-68A, is a pH-dependent, two-step, covalent inhibitor of Escherichia coli LpxC that competes with UDP to bind the enzyme in the first step of inhibition. Compound 1-68A exhibits a K(I) of 54 muM and a maximal rate of inactivation (k(inact)) of 1.7 min(-1) at pH 7.4. Dithiothreitol, glutathione and the C207A mutant of E. coli LpxC prevent the formation of a covalent complex by 1-68A, suggesting a role for Cys-207 in inhibition. The inhibitory activity of 1-68A and a panel of synthetic analogues identified moieties necessary for inhibition. 1-68A and a 2-dehydroxy analogue, 1-68Aa, inhibit several purified LpxC orthologues. These compounds may provide new scaffolds for extension of existing LpxC-inhibiting antibiotics to target the UDP binding pocket.
Barb
Adam W
AW
Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA.
Leavy
Tanya M
TM
Robins
Lori I
LI
Guan
Ziqiang
Z
Six
David A
DA
Zhou
Pei
P
Hangauer
Matthew J
MJ
Bertozzi
Carolyn R
CR
Raetz
Christian R H
CR
D000581:Amidohydrolases / Q000037:antagonists & inhibitors*; D000900:Anti-Bacterial Agents / Q000737:chemistry*; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology; D004926:Escherichia coli / Q000187:drug effects; D029968:Escherichia coli Proteins / Q000187:drug effects; D007700:Kinetics; D013329:Structure-Activity Relationship; D014529:Uridine / Q000031:analogs & derivatives* / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D004791:Enzyme Inhibitors; D029968:Escherichia coli Proteins; D000581:Amidohydrolases; C097307:UDP-3-O-acyl-N-acetylglucosamine deacetylase; D014529:Uridine