Evidence for an oxyanion hole in serine <i>β</i>-lactamases and <scp>dd</scp>-peptidases

Murphy, Bryan P.; Pratt, Robertson

doi:10.1042/bj2560669

Cited by 68 publications

(61 citation statements)

References 30 publications

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“…The G243A substitution is not conserved among ␤-lactamases, and this change might create subtle rearrangements in the disulfide bond. The T237 amino acid, together with the S70 residue, forms an oxyanion hole, which houses the ␤-lactam carbonyl of the acyl-enzyme intermediate (27). Position 237, usually occupied by an Ala or Ser in most class A ␤-lactamases, corresponds to a Thr residue in GES-1 but also in the PER-1 ESBL and in the class A KPC-2 carbapenemase.…”

Section: Discussionmentioning

confidence: 99%

In Vitro Prediction of the Evolution of GES-1 β-Lactamase Hydrolytic Activity

Bontron

Poirel

Nordmann

2015

Antimicrob Agents Chemother

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Resistance to ␤-lactams is constantly increasing due to the emergence of totally new enzymes but also to the evolution of preexisting ␤-lactamases. GES-1 is a clinically relevant extended-spectrum ␤-lactamase (ESBL) that hydrolyzes penicillins and broadspectrum cephalosporins but spares monobactams and carbapenems. However, several GES-1 variants (i.e., GES-2 and GES-5) previously identified among clinical isolates display an extended spectrum of activity toward carbapenems. To study the evolution potential of the GES-1 ␤-lactamase, this enzyme was submitted to in vitro-directed evolution, with selection on increasing concentrations of the cephalosporin cefotaxime, the monobactam aztreonam, or the carbapenem imipenem. The highest resistance levels were conferred by a combination of up to four substitutions. The A6T-E104K-G243A variant selected on cefotaxime and the A6T-E104K-T237A-G243A variant selected on aztreonam conferred high resistance to cefotaxime, ceftazidime, and aztreonam. Conversely, the A6T-G170S variant selected on imipenem conferred high resistance to imipenem and cefoxitin. Of note, the A6T substitution involved in higher MICs for all ␤-lactams is located in the leader peptide of the GES enzyme and therefore is not present in the mature protein. Acquired cross-resistance was not observed, since selection with cefotaxime or aztreonam did not select for resistance to imipenem, and vice versa. Here, we demonstrate that the ␤-lactamase GES-1 exhibits peculiar properties, with a significant potential to gain activity against broad-spectrum cephalosporins, monobactams, and carbapenems.

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Section: Discussionmentioning

confidence: 99%

In Vitro Prediction of the Evolution of GES-1 β-Lactamase Hydrolytic Activity

Bontron

Poirel

Nordmann

2015

Antimicrob Agents Chemother

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“…7) (295). Proper position in this oxyanion hole, the binding pocket for the ␤-lactam carbonyl, is important for both initial enzyme acylation and hydrolysis of the ester bond (277,425). A conformation which places the ␤-lactam carbonyl outside of this electrophilic center may be delayed in hydrolysis.…”

Section: Inhibitory Activity Of Carbapenemsmentioning

confidence: 99%

Three Decades of β-Lactamase Inhibitors

Drawz¹,

2010

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SUMMARYSince the introduction of penicillin, β-lactam antibiotics have been the antimicrobial agents of choice. Unfortunately, the efficacy of these life-saving antibiotics is significantly threatened by bacterial β-lactamases. β-Lactamases are now responsible for resistance to penicillins, extended-spectrum cephalosporins, monobactams, and carbapenems. In order to overcome β-lactamase-mediated resistance, β-lactamase inhibitors (clavulanate, sulbactam, and tazobactam) were introduced into clinical practice. These inhibitors greatly enhance the efficacy of their partner β-lactams (amoxicillin, ampicillin, piperacillin, and ticarcillin) in the treatment of seriousEnterobacteriaceaeand penicillin-resistant staphylococcal infections. However, selective pressure from excess antibiotic use accelerated the emergence of resistance to β-lactam-β-lactamase inhibitor combinations. Furthermore, the prevalence of clinically relevant β-lactamases from other classes that are resistant to inhibition is rapidly increasing. There is an urgent need for effective inhibitors that can restore the activity of β-lactams. Here, we review the catalytic mechanisms of each β-lactamase class. We then discuss approaches for circumventing β-lactamase-mediated resistance, including properties and characteristics of mechanism-based inactivators. We next highlight the mechanisms of action and salient clinical and microbiological features of β-lactamase inhibitors. We also emphasize their therapeutic applications. We close by focusing on novel compounds and the chemical features of these agents that may contribute to a “second generation” of inhibitors. The goal for the next 3 decades will be to design inhibitors that will be effective for more than a single class of β-lactamases.

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“…This strand contributes two residues Atomic Resolution of CTX-M b-Lactamases essential to catalytic activity, Lys234 and the main chain of Ser237, which forms part of the enzyme's "oxyanion" hole, 38,39 and several substraterecognition residues. In the CTX-M ESBLs, unlike those of TEM and SHV, increased activity against the bulky third-generation cephalosporins, especially ceftazidime, appears to come not from gross enlargement of the active site, but from increased flexibility of this strand, and possibly other regions.…”

Section: Activity and Stability Tradeoffmentioning

confidence: 99%