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Mechanistic insights into β-lactamase-catalysed carbapenem degradation through product characterisation

Abstract:
β-Lactamases are a major threat to the clinical use of carbapenems, which are often antibiotics of last resort. Despite this, the reaction outcomes and mechanisms by which β-lactamases degrade carbapenems are still not fully understood. The carbapenem bicyclic core consists of a β-lactam ring fused to a pyrroline ring. Following β-lactamase-mediated opening of the β-lactam, the pyrroline may interconvert between an enamine (2-pyrroline) form and two epimeric imine (1-pyrroline) forms; previous crystallographic and spectroscopic studies have reported all three of these forms in the contexts of hydrolysis by different β-lactamases. As we show by NMR spectroscopy, the serine β-lactamases (KPC-2, SFC-1, CMY-10, OXA-23, and OXA-48) and metallo-β-lactamases (NDM-1, VIM-1, BcII, CphA, and L1) tested all degrade carbapenems to preferentially give the Δ² (enamine) and/or (R)-Δ¹ (imine) products. Rapid non-enzymatic tautomerisation of the Δ² product to the (R)-Δ¹ product prevents assignment of the nascent enzymatic product by NMR. The observed stereoselectivity implies that carbapenemases control the form of their pyrroline ring intermediate(s)/product(s), thereby preventing pyrroline tautomerisation from inhibiting catalysis.
Publication status:
Published
Peer review status:
Peer reviewed

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Publisher copy:
10.1038/s41598-019-49264-0

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Institution:
University of Oxford
Division:
MPLS
Department:
Chemistry
Sub department:
Organic Chemistry
Role:
Author
More by this author
Institution:
University of Oxford
Department:
Chemistry
Role:
Author
More by this author
Institution:
University of Oxford
Department:
Chemistry
Role:
Author


Publisher:
Nature Research
Journal:
Scientific Reports More from this journal
Volume:
9
Issue:
2019
Article number:
13608
Publication date:
2019-09-20
Acceptance date:
2019-08-15
DOI:
ISSN:
2045-2322


Pubs id:
pubs:1045693
UUID:
uuid:cd986cf5-f433-4b32-b378-30edc5734827
Local pid:
pubs:1045693
Source identifiers:
1045693
Deposit date:
2019-08-16
ARK identifier:

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