1i2s

<StructureSection load='1i2s' size='340' side='right' caption='[[1i2s]], [[Resolution|resolution]] 1.70&Aring;' scene=''>

<table><tr><td colspan='2'>[[1i2s]] is a 2 chain structure with sequence from [http://en.wikipedia.org/wiki/"clostridium_licheniforme"_weigmann_1898 "clostridium licheniforme" weigmann 1898]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1I2S OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1I2S FirstGlance]. <br>

</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=CIT:CITRIC+ACID'>CIT</scene>, <scene name='pdbligand=NA:SODIUM+ION'>NA</scene></td></tr>

<tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[1i2w|1i2w]]</td></tr>

<tr id='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[http://en.wikipedia.org/wiki/Beta-lactamase Beta-lactamase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.5.2.6 3.5.2.6] </span></td></tr>

<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1i2s FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1i2s OCA], [http://pdbe.org/1i2s PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=1i2s RCSB], [http://www.ebi.ac.uk/pdbsum/1i2s PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=1i2s ProSAT]</span></td></tr>

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== Publication Abstract from PubMed ==

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.

 

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== References ==

[[Category: Clostridium licheniforme weigmann 1898]]

[[Category: Beta-lactamase]]

[[Category: Charlier, P]]

[[Category: Dive, G]]

[[Category: Fonze, E]]

[[Category: Frere, J M]]

[[Category: Sauvage, E]]

[[Category: Vanhove, M]]

[[Category: Serine beta-lactamase]]