1fsy
From Proteopedia
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'''AMPC BETA-LACTAMASE FROM E. COLI COMPLEXED WITH INHIBITOR CLOXACILLINBORONIC ACID''' | '''AMPC BETA-LACTAMASE FROM E. COLI COMPLEXED WITH INHIBITOR CLOXACILLINBORONIC ACID''' | ||
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[[Category: Shoichet, B K.]] | [[Category: Shoichet, B K.]] | ||
[[Category: Wu, C Y.]] | [[Category: Wu, C Y.]] | ||
| - | [[Category: | + | [[Category: Beta-lactamase]] |
| - | [[Category: | + | [[Category: Cephalosporinase]] |
| - | [[Category: | + | [[Category: Serine hydrolase]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 16:43:52 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 13:43, 2 May 2008
AMPC BETA-LACTAMASE FROM E. COLI COMPLEXED WITH INHIBITOR CLOXACILLINBORONIC ACID
Overview
BACKGROUND: Penicillins and cephalosporins are among the most widely used and successful antibiotics. The emergence of resistance to these beta-lactams, most often through bacterial expression of beta-lactamases, threatens public health. To understand how beta-lactamases recognize their substrates, it would be helpful to know their binding energies. Unfortunately, these have been difficult to measure because beta-lactams form covalent adducts with beta-lactamases. This has complicated functional analyses and inhibitor design. RESULTS: To investigate the contribution to interaction energy of the key amide (R1) side chain of beta-lactam antibiotics, eight acylglycineboronic acids that bear the side chains of characteristic penicillins and cephalosporins, as well as four other analogs, were synthesized. These transition-state analogs form reversible adducts with serine beta-lactamases. Therefore, binding energies can be calculated directly from K(i) values. The K(i) values measured span four orders of magnitude against the Group I beta-lactamase AmpC and three orders of magnitude against the Group II beta-lactamase TEM-1. The acylglycineboronic acids have K(i) values as low as 20 nM against AmpC and as low as 390 nM against TEM-1. The inhibitors showed little activity against serine proteases, such as chymotrypsin. R1 side chains characteristic of beta-lactam inhibitors did not have better affinity for AmpC than did side chains characteristic of beta-lactam substrates. Two of the inhibitors reversed the resistance of pathogenic bacteria to beta-lactams in cell culture. Structures of two inhibitors in their complexes with AmpC were determined by X-ray crystallography to 1.90 A and 1.75 A resolution; these structures suggest interactions that are important to the affinity of the inhibitors. CONCLUSIONS: Acylglycineboronic acids allow us to begin to dissect interaction energies between beta-lactam side chains and beta-lactamases. Surprisingly, there is little correlation between the affinity contributed by R1 side chains and their occurrence in beta-lactam inhibitors or beta-lactam substrates of serine beta-lactamases. Nevertheless, presented in acylglycineboronic acids, these side chains can lead to inhibitors with high affinities and specificities. The structures of their complexes with AmpC give a molecular context to their affinities and may guide the design of anti-resistance compounds in this series.
About this Structure
1FSY is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
Reference
Energetic, structural, and antimicrobial analyses of beta-lactam side chain recognition by beta-lactamases., Caselli E, Powers RA, Blasczcak LC, Wu CY, Prati F, Shoichet BK, Chem Biol. 2001 Jan;8(1):17-31. PMID:11182316 Page seeded by OCA on Fri May 2 16:43:52 2008
