title: Inactivation of a class A and a class C β-lactamase by 6β-(hydroxymethyl)penicillanic acid sulfone.
abstract: β-Lactamase inhibitors (clavulanic acid, sulbactam, and tazobactam) contribute significantly to the longevity of the β-lactam antibiotics used to treat serious infections. In the quest to design more potent compounds and to understand the mechanism of action of known inhibitors, 6β-(hydroxymethyl)penicillanic acid sulfone (6β-HM-sulfone) was tested against isolates expressing the class A TEM-1 β-lactamase and a clinically important variant of the AmpC cephalosporinase of Pseudomonas aeruginosa, PDC-3. The addition of the 6β-HM-sulfone inhibitor to ampicillin was highly effective. 6β-HM-sulfone inhibited TEM-1 with an IC(50) of 12 ± 2 nM and PDC-3 with an IC(50) of 180 ± 36 nM, and displayed lower partition ratios than commercial inhibitors, with partition ratios (k(cat)/k(inact)) equal to 174 for TEM-1 and 4 for PDC-3. Measured for 20 h, 6β-HM-sulfone demonstrated rapid, first-order inactivation kinetics with the extent of inactivation being related to the concentration of inhibitor for both TEM-1 and PDC-3. Using mass spectrometry to gain insight into the intermediates of inactivation of this inhibitor, 6β-HM-sulfone was found to form a major adduct of +247 ± 5 Da with TEM-1 and +245 ± 5 Da with PDC-3, suggesting that the covalently bound, hydrolytically stabilized acyl-enzyme has lost a molecule of water (HOH). Minor adducts of +88 ± 5 Da with TEM-1 and +85 ± 5 Da with PDC-3 revealed that fragmentation of the covalent adduct can result but appeared to occur slowly with both enzymes. 6β-HM-sulfone is an effective and versatile β-lactamase inhibitor of representative class A and C enzymes.
authors.affiliation: Research Service, Louis Stokes Cleveland Department of Veteran Affairs Medical Center, Cleveland, OH 44106, USA.
authors.forename: Krisztina M
authors.initials: KM
authors.lastname: Papp-Wallace
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Bethel
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Gootz
authors.forename: Wenchi
authors.initials: W
authors.lastname: Shang
authors.forename: Justin
authors.initials: J
authors.lastname: Stroh
authors.forename: William
authors.initials: W
authors.lastname: Lau
authors.forename: Dale
authors.initials: D
authors.lastname: McLeod
authors.forename: Loren
authors.initials: L
authors.lastname: Price
authors.forename: Anthony
authors.initials: A
authors.lastname: Marfat
authors.forename: Anne
authors.initials: A
authors.lastname: Distler
authors.forename: Sarah M
authors.initials: SM
authors.lastname: Drawz
authors.forename: Hansong
authors.initials: H
authors.lastname: Chen
authors.forename: Emily
authors.initials: E
authors.lastname: Harry
authors.forename: Micheal
authors.initials: M
authors.lastname: Nottingham
authors.forename: Paul R
authors.initials: PR
authors.lastname: Carey
authors.forename: John D
authors.initials: JD
authors.lastname: Buynak
authors.forename: Robert A
authors.initials: RA
authors.lastname: Bonomo
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D020134:Catalytic Domain; D003198:Computer Simulation; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology / Q000235:genetics; D008958:Models, Molecular; D015394:Molecular Structure; D011487:Protein Conformation; D011550:Pseudomonas aeruginosa / Q000201:enzymology; D013407:Sulbactam / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology*; D065093:beta-Lactamase Inhibitors; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism*
chemical_list: C570478:6beta-(hydroxymethyl)penicillanic acid sulfone; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D065093:beta-Lactamase Inhibitors; C048795:AmpC beta-lactamases; D001618:beta-Lactamases; C034413:beta-lactamase TEM-1; D013407:Sulbactam