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==Structure of CTX-M-15 E166Q mutant crystallised in the presence of tazobactam (AAI101)== | ==Structure of CTX-M-15 E166Q mutant crystallised in the presence of tazobactam (AAI101)== | ||
<StructureSection load='7bdr' size='340' side='right'caption='[[7bdr]]' scene=''> | <StructureSection load='7bdr' size='340' side='right'caption='[[7bdr]], [[Resolution|resolution]] 0.91Å' scene=''> | ||
== Structural highlights == | == Structural highlights == | ||
<table><tr><td colspan='2'>Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=7BDR OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=7BDR FirstGlance]. <br> | <table><tr><td colspan='2'>[[7bdr]] is a 1 chain structure. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=7BDR OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=7BDR FirstGlance]. <br> | ||
</td></tr><tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=7bdr FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=7bdr OCA], [https://pdbe.org/7bdr PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=7bdr RCSB], [https://www.ebi.ac.uk/pdbsum/7bdr PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=7bdr ProSAT]</span></td></tr> | </td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CL:CHLORIDE+ION'>CL</scene>, <scene name='pdbligand=NA:SODIUM+ION'>NA</scene>, <scene name='pdbligand=SO4:SULFATE+ION'>SO4</scene></td></tr> | ||
<tr id='NonStdRes'><td class="sblockLbl"><b>[[Non-Standard_Residue|NonStd Res:]]</b></td><td class="sblockDat"><scene name='pdbligand=DAL:D-ALANINE'>DAL</scene></td></tr> | |||
<tr id='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[https://en.wikipedia.org/wiki/Beta-lactamase Beta-lactamase], with EC number [https://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'>[https://proteopedia.org/fgij/fg.htm?mol=7bdr FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=7bdr OCA], [https://pdbe.org/7bdr PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=7bdr RCSB], [https://www.ebi.ac.uk/pdbsum/7bdr PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=7bdr ProSAT]</span></td></tr> | |||
</table> | </table> | ||
<div style="background-color:#fffaf0;"> | |||
== Publication Abstract from PubMed == | |||
beta-Lactamases hydrolyze beta-lactam antibiotics and are major determinants of antibiotic resistance in Gram-negative pathogens. Enmetazobactam (formerly AAI101) and tazobactam are penicillanic acid sulfone (PAS) beta-lactamase inhibitors that differ by an additional methyl group on the triazole ring of enmetazobactam, rendering it zwitterionic. In this study, ultrahigh-resolution X-ray crystal structures and mass spectrometry revealed the mechanism of PAS inhibition of CTX-M-15, an extended-spectrum beta-lactamase (ESBL) globally disseminated among Enterobacterales. CTX-M-15 crystals grown in the presence of enmetazobactam or tazobactam revealed loss of the Ser70 hydroxyl group and formation of a lysinoalanine cross-link between Lys73 and Ser70, two residues critical for catalysis. Moreover, the residue at position 70 undergoes epimerization, resulting in formation of a d-amino acid. Cocrystallization of enmetazobactam or tazobactam with CTX-M-15 with a Glu166Gln mutant revealed the same cross-link, indicating that this modification is not dependent on Glu166-catalyzed deacylation of the PAS-acylenzyme. A cocrystal structure of enmetazobactam with CTX-M-15 with a Lys73Ala mutation indicates that epimerization can occur without cross-link formation and positions the Ser70 Cbeta closer to Lys73, likely facilitating formation of the Ser70-Lys73 cross-link. A crystal structure of a tazobactam-derived imine intermediate covalently linked to Ser70, obtained after 30 min of exposure of CTX-M-15 crystals to tazobactam, supports formation of an initial acylenzyme by PAS inhibitors on reaction with CTX-M-15. These data rationalize earlier results showing CTX-M-15 deactivation by PAS inhibitors to involve loss of protein mass, and they identify a distinct mechanism of beta-lactamase inhibition by these agents. IMPORTANCE beta-Lactams are the most prescribed antibiotic class for treating bacterial diseases, but their continued efficacy is threatened by bacterial strains producing beta-lactamase enzymes that catalyze their inactivation. The CTX-M family of ESBLs are major contributors to beta-lactam resistance in Enterobacterales, preventing effective treatment with most penicillins and cephalosporins. Combining beta-lactams with beta-lactamase inhibitors (BLIs) is a validated route to overcome such resistance. Here, we describe how exposure to enmetazobactam and tazobactam, BLIs based on a penicillanic acid sulfone (PAS) scaffold, leads to a protein modification in CTX-M-15, resulting in irremediable inactivation of this most commonly encountered member of the CTX-M family. High-resolution X-ray crystal structures showed that PAS exposure induces formation of a cross-link between Ser70 and Lys73, two residues critical to beta-lactamase function. This previously undescribed mechanism of inhibition furthers our understanding of beta-lactamase inhibition by classical PAS inhibitors and provides a basis for further, rational inhibitor development. | |||
Penicillanic Acid Sulfones Inactivate the Extended-Spectrum beta-Lactamase CTX-M-15 through Formation of a Serine-Lysine Cross-Link: an Alternative Mechanism of beta-Lactamase Inhibition.,Hinchliffe P, Tooke CL, Bethel CR, Wang B, Arthur C, Heesom KJ, Shapiro S, Schlatzer DM, Papp-Wallace KM, Bonomo RA, Spencer J mBio. 2022 Jun 28;13(3):e0179321. doi: 10.1128/mbio.01793-21. Epub 2022 May 25. PMID:35612361<ref>PMID:35612361</ref> | |||
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | |||
</div> | |||
<div class="pdbe-citations 7bdr" style="background-color:#fffaf0;"></div> | |||
== References == | |||
<references/> | |||
__TOC__ | __TOC__ | ||
</StructureSection> | </StructureSection> | ||
[[Category: Beta-lactamase]] | |||
[[Category: Large Structures]] | [[Category: Large Structures]] | ||
[[Category: Hinchliffe P]] | [[Category: Hinchliffe, P]] | ||
[[Category: Spencer J]] | [[Category: Spencer, J]] | ||
[[Category: Tooke | [[Category: Tooke, C L]] | ||
[[Category: Antibiotic resistance]] | |||
[[Category: Antimicrobial protein]] | |||
[[Category: Cross-link]] | |||
[[Category: Inhibitor]] | |||