1I2S

BETA-LACTAMASE FROM BACILLUS LICHENIFORMIS BS3

Summary for 1I2S

• Entry DOI: 10.2210/pdb1i2s/pdb
• Related: 1I2W
• Descriptor: BETA-LACTAMASE, SODIUM ION, CITRIC ACID, ... (4 entities in total)
• Functional Keywords: serine beta-lactamase, hydrolase, antibiotic resistance
• Biological source: Bacillus licheniformis
• Cellular location: Cell membrane ; Lipid-anchor : P00808
• Total number of polymer chains: 2
• Total formula weight: 63002.47

Authors

Fonze, E.,Vanhove, M.,Dive, G.,Sauvage, E.,Frere, J.M.,Charlier, P. (deposition date: 2001-02-12, release date: 2002-03-13, Last modification date: 2024-02-07)

Primary citation

Fonze, E.,Vanhove, M.,Dive, G.,Sauvage, E.,Frere, J.M.,Charlier, P.
Crystal structures of the Bacillus licheniformis BS3 class A beta-lactamase and of the acyl-enzyme adduct formed with cefoxitin
Biochemistry, 41:1877-1885, 2002

PubMed Abstract: 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 7alpha-methoxy 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 A 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.

PubMed: 11827533
DOI: 10.1021/bi015789k

Experimental method

X-RAY DIFFRACTION (1.7 Å)