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| [[Image:1c3b.gif|left|200px]]<br /><applet load="1c3b" size="350" color="white" frame="true" align="right" spinBox="true"
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| caption="1c3b, resolution 2.25Å" />
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| '''AMPC BETA-LACTAMASE FROM E. COLI COMPLEXED WITH INHIBITOR, BENZO(B)THIOPHENE-2-BORONIC ACID (BZB)'''<br />
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| ==Overview== | | ==AMPC BETA-LACTAMASE FROM E. COLI COMPLEXED WITH INHIBITOR, BENZO(B)THIOPHENE-2-BORONIC ACID (BZB)== |
| Beta-lactamases are the major resistance mechanism to beta-lactam antibiotics and pose a growing threat to public health. Recently, bacteria have become resistant to beta-lactamase inhibitors, making this problem pressing. In an effort to overcome this resistance, non-beta-lactam inhibitors of beta-lactamases were investigated for complementarity to the structure of AmpC beta-lactamase from Escherichia coli. This led to the discovery of an inhibitor, benzo(b)thiophene-2-boronic acid (BZBTH2B), which inhibited AmpC with a Ki of 27 nM. This inhibitor is chemically dissimilar to beta-lactams, raising the question of what specific interactions are responsible for its activity. To answer this question, the X-ray crystallographic structure of BZBTH2B in complex with AmpC was determined to 2.25 A resolution. The structure reveals several unexpected interactions. The inhibitor appears to complement the conserved, R1-amide binding region of AmpC, despite lacking an amide group. Interactions between one of the boronic acid oxygen atoms, Tyr150, and an ordered water molecule suggest a mechanism for acid/base catalysis and a direction for hydrolytic attack in the enzyme catalyzed reaction. To investigate how a non-beta-lactam inhibitor would perform against resistant bacteria, BZBTH2B was tested in antimicrobial assays. BZBTH2B significantly potentiated the activity of a third-generation cephalosporin against AmpC-producing resistant bacteria. This inhibitor was unaffected by two common resistance mechanisms that often arise against beta-lactams in conjunction with beta-lactamases. Porin channel mutations did not decrease the efficacy of BZBTH2B against cells expressing AmpC. Also, this inhibitor did not induce expression of AmpC, a problem with many beta-lactams. The structure of the BZBTH2B/AmpC complex provides a starting point for the structure-based elaboration of this class of non-beta-lactam inhibitors.
| | <StructureSection load='1c3b' size='340' side='right'caption='[[1c3b]], [[Resolution|resolution]] 2.25Å' scene=''> |
| | | == Structural highlights == |
| ==About this Structure== | | <table><tr><td colspan='2'>[[1c3b]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Escherichia_coli_K-12 Escherichia coli K-12]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1C3B OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1C3B FirstGlance]. <br> |
| 1C3B is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with <scene name='pdbligand=BZB:'>BZB</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [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] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1C3B OCA].
| | </td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.25Å</td></tr> |
| | | <tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=BZB:BENZO[B]THIOPHENE-2-BORONIC+ACID'>BZB</scene></td></tr> |
| ==Reference== | | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1c3b FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1c3b OCA], [https://pdbe.org/1c3b PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1c3b RCSB], [https://www.ebi.ac.uk/pdbsum/1c3b PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1c3b ProSAT]</span></td></tr> |
| The complexed structure and antimicrobial activity of a non-beta-lactam inhibitor of AmpC beta-lactamase., Powers RA, Blazquez J, Weston GS, Morosini MI, Baquero F, Shoichet BK, Protein Sci. 1999 Nov;8(11):2330-7. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=10595535 10595535]
| | </table> |
| [[Category: Beta-lactamase]]
| | == Function == |
| [[Category: Escherichia coli]] | | [https://www.uniprot.org/uniprot/AMPC_ECOLI AMPC_ECOLI] This protein is a serine beta-lactamase with a substrate specificity for cephalosporins. |
| [[Category: Single protein]] | | == Evolutionary Conservation == |
| [[Category: Baquero, F.]] | | [[Image:Consurf_key_small.gif|200px|right]] |
| [[Category: Blazquez, J.]] | | Check<jmol> |
| [[Category: Morosini, M I.]] | | <jmolCheckbox> |
| [[Category: Powers, R A.]] | | <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/c3/1c3b_consurf.spt"</scriptWhenChecked> |
| [[Category: Shoichet, B K.]] | | <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked> |
| [[Category: Weston, G S.]] | | <text>to colour the structure by Evolutionary Conservation</text> |
| [[Category: BZB]]
| | </jmolCheckbox> |
| [[Category: beta-lactamase]]
| | </jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/main_output.php?pdb_ID=1c3b ConSurf]. |
| [[Category: cephalosporinase]]
| | <div style="clear:both"></div> |
| [[Category: serine hydrolase]]
| | __TOC__ |
| | | </StructureSection> |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:01:56 2008''
| | [[Category: Escherichia coli K-12]] |
| | [[Category: Large Structures]] |
| | [[Category: Baquero F]] |
| | [[Category: Blazquez J]] |
| | [[Category: Morosini MI]] |
| | [[Category: Powers RA]] |
| | [[Category: Shoichet BK]] |
| | [[Category: Weston GS]] |
