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1c3b

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{{STRUCTURE_1c3b| PDB=1c3b | SCENE= }}
{{STRUCTURE_1c3b| PDB=1c3b | SCENE= }}
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'''AMPC BETA-LACTAMASE FROM E. COLI COMPLEXED WITH INHIBITOR, BENZO(B)THIOPHENE-2-BORONIC ACID (BZB)'''
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===AMPC BETA-LACTAMASE FROM E. COLI COMPLEXED WITH INHIBITOR, BENZO(B)THIOPHENE-2-BORONIC ACID (BZB)===
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==Overview==
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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.
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==About this Structure==
==About this Structure==
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[[Category: Cephalosporinase]]
[[Category: Cephalosporinase]]
[[Category: Serine hydrolase]]
[[Category: Serine hydrolase]]
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Revision as of 17:08, 30 June 2008

Image:1c3b.png

Template:STRUCTURE 1c3b

AMPC BETA-LACTAMASE FROM E. COLI COMPLEXED WITH INHIBITOR, BENZO(B)THIOPHENE-2-BORONIC ACID (BZB)

Template:ABSTRACT PUBMED 10595535

About this Structure

1C3B is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.

Reference

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:10595535

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