Reference : Crystal structures of the Bacillus licheniformis BS3 class A beta-lactamase and of th...
Scientific journals : Article
Life sciences : Biochemistry, biophysics & molecular biology
Crystal structures of the Bacillus licheniformis BS3 class A beta-lactamase and of the acyl-enzyme adduct formed with cefoxitin
Fonzé, Evelyne [> > > >]
Vanhove, Mac [> > > >]
Dive, Georges [Université de Liège - ULiège > > Centre d'ingénierie des protéines >]
Sauvage, Eric mailto [Université de Liège - ULiège > > Centre d'ingénierie des protéines >]
Frère, Jean-Marie mailto [Université de Liège - ULiège > Département des sciences de la vie > Département des sciences de la vie >]
Charlier, Paulette mailto [Université de Liège - ULiège > > Centre d'ingénierie des protéines >]
American Chemical Society
Yes (verified by ORBi)
[en] The Bacillus licheniformis BS3 beta-lactamase catalyzes the hydrolysis of the beta-lactam ring of penicillins, cephalosporins, and related compounds. The production of beta-lactamases is the most common and thoroughly studied cause of antibiotic resistance. Although they escape the hydrolytic activity of the prototypical Staphylococcus aureus beta-lactamase, many cephems are good substrates for a large number of beta-lactamases. However, the introduction of a 7alpha-methoxy substituent, as in cefoxitin, extends their antibacterial spectrum to many cephalosporin-resistant Gram-negative bacteria. The 7alphamethoxy group selectively reduces the hydrolytic action of many beta-lactamases without having a significant effect on the affinity for the target enzymes, the membrane penicillin-binding proteins. We report here the crystallographic structures of the BS3 enzyme and its acyl-enzyme adduct with cefoxitin at 1.7 Angstrom resolution. The comparison of the two structures reveals a covalent acyl-enzyme adduct with perturbed active site geometry, involving a different conformation of the Omega-loop that bears the essential catalytic Glu166 residue. This deformation is induced by the cefoxitin side chain whose position is constrained by the presence of the alpha-methoxy group. The hydrolytic water molecule is also removed from the active site by the 7beta-carbonyl of the acyl intermediate. In light of the interactions and steric hindrances in the active site of the structure of the BS3-cefoxitin acyl-enzyme adduct, the crucial role of the conserved Asn132 residue is confirmed and a better understanding of the kinetic results emerges.
Researchers ; Professionals

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