Non‐Hydrolytic β‐Lactam Antibiotic Fragmentation by l,d‐Transpeptidases and Serine β‐Lactamase Cysteine Variants |
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Authors: | Christopher T Lohans H T Henry Chan Tika R Malla Kiran Kumar Jos J A G Kamps Darius J B McArdle Emma vanGroesen Mariska deMunnik Catherine L Tooke James Spencer Robert S Paton Jürgen Brem Christopher J Schofield |
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Institution: | Christopher T. Lohans,H. T. Henry Chan,Tika R. Malla,Kiran Kumar,Jos J. A. G. Kamps,Darius J. B. McArdle,Emma van Groesen,Mariska de Munnik,Catherine L. Tooke,James Spencer,Robert S. Paton,Jürgen Brem,Christopher J. Schofield |
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Abstract: | Enzymes often use nucleophilic serine, threonine, and cysteine residues to achieve the same type of reaction; the underlying reasons for this are not understood. While bacterial d,d ‐transpeptidases (penicillin‐binding proteins) employ a nucleophilic serine, l,d ‐transpeptidases use a nucleophilic cysteine. The covalent complexes formed by l,d ‐transpeptidases with some β‐lactam antibiotics undergo non‐hydrolytic fragmentation. This is not usually observed for penicillin‐binding proteins, or for the related serine β‐lactamases. Replacement of the nucleophilic serine of serine β‐lactamases with cysteine yields enzymes which fragment β‐lactams via a similar mechanism as the l,d ‐transpeptidases, implying the different reaction outcomes are principally due to the formation of thioester versus ester intermediates. The results highlight fundamental differences in the reactivity of nucleophilic serine and cysteine enzymes, and imply new possibilities for the inhibition of nucleophilic enzymes. |
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Keywords: | Antibiotikaresistenz Fragmentierung Hydrolasen Transpeptidasen β -Lactamasen |
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