title: Novel fragments of clavulanate observed in the structure of the class A β-lactamase from Bacillus licheniformis BS3.
abstract: OBJECTIVE
  Our aim was to unravel the inactivation pathway of the class A β-lactamase produced by Bacillus licheniformis BS3 (BS3) by clavulanate.
  
  
  METHODS
  The interaction between clavulanate and BS3 was studied by X-ray crystallography, pre-steady-state kinetics and mass spectrometry.
  
  
  RESULTS
  The analysis of the X-ray structure of the complex yielded by the reaction between clavulanate and BS3 indicates that the transient inactivated form, namely the cis-trans enamine complex, is hydrolysed to an ethane-imine ester covalently linked to the active site serine and a pentan-3-one-5-ol acid. It is the first time that this mechanism has been observed in an inactivated β-lactamase. Furthermore, the ionic interactions made by the carboxylic group of pentan-3-one-5-ol may provide an understanding of the decarboxylation process of the trans-enamine observed in the non-productive complex observed for the interaction between clavulanate and SHV-1 and Mycobacterium tuberculosis β-lactamase (Mtu).
  
  
  CONCLUSIONS
  This work provides a comprehensive clavulanate hydrolysis pathway accounting for the observed acyl-enzyme structures of class A β-lactamase/clavulanate adducts.
authors: Laboratorio de Resistencia Bacteriana, Facultad de Farmacia y Bioquímica,  Universidad de Buenos Aires, Junin 956, (1113) Buenos Aires,  Argentina.
authors: Pablo
authors: P
authors: Power
authors: Paola
authors: P
authors: Mercuri
authors: Raphaël
authors: R
authors: Herman
authors: Frédéric
authors: F
authors: Kerff
authors: Gabriel
authors: G
authors: Gutkind
authors: Georges
authors: G
authors: Dive
authors: Moreno
authors: M
authors: Galleni
authors: Paulette
authors: P
authors: Charlier
authors: Eric
authors: E
authors: Sauvage
mesh_terms: D001407:Bacillus / Q000201:enzymology*; D019818:Clavulanic Acid / Q000737:chemistry* / Q000378:metabolism*; D018360:Crystallography, X-Ray; D004791:Enzyme Inhibitors / Q000378:metabolism*; D006868:Hydrolysis; D007700:Kinetics; D013058:Mass Spectrometry; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D065093:beta-Lactamase Inhibitors; D001618:beta-Lactamases / Q000737:chemistry*
chemical_list: D004791:Enzyme Inhibitors; D065093:beta-Lactamase Inhibitors; D019818:Clavulanic Acid; D001618:beta-Lactamases