2a49
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Crystal structure of clavulanic acid bound to E166A variant of SHV-1 beta-lactamase
OverviewOverview
Antibiotic resistance mediated by constantly evolving beta-lactamases is a, serious threat to human health. The mechanism of inhibition of these, enzymes by therapeutic beta-lactamase inhibitors is probed using a novel, approach involving Raman microscopy and x-ray crystallography. We have, presented here the high resolution crystal structures of the, beta-lactamase inhibitors sulbactam and clavulanic acid bound to the, deacylation-deficient E166A variant of SHV-1 beta-lactamase. Our previous, Raman measurements have identified the trans-enamine species for both, inhibitors and were used to guide the soaking time and concentration to, achieve full occupancy of the active sites. The two inhibitor-bound x-ray, structures revealed a linear trans-enamine intermediate covalently, attached to the active site Ser-70 residue. This intermediate was thought, to play a key role in the transient inhibition of class A beta-lactamases., Both the Raman and x-ray data indicated that the clavulanic acid, intermediate is decarboxylated. When compared with our previously, determined tazobactam-bound inhibitor structure, our new inhibitor-bound, structures revealed an increased disorder in the tail region of the, inhibitors as well as in the enamine skeleton. The x-ray crystallographic, observations correlated with the broadening of the O-C=C-N (enamine), symmetric stretch Raman band near 1595 cm(-1). Band broadening in the, sulbactam and clavulanic acid inter-mediates reflected a heterogeneous, conformational population that results from variations of torsional angles, in the O-(C=O)-C=C=NH-C skeleton. These observations led us to conclude, that the conformational stability of the trans-enamine form is critical, for their transient inhibitory efficacy.
About this StructureAbout this Structure
2A49 is a Single protein structure of sequence from Klebsiella pneumoniae with TEM, MA4 and EPE as ligands. Active as Beta-lactamase, with EC number 3.5.2.6 Full crystallographic information is available from OCA.
ReferenceReference
High resolution crystal structures of the trans-enamine intermediates formed by sulbactam and clavulanic acid and E166A SHV-1 {beta}-lactamase., Padayatti PS, Helfand MS, Totir MA, Carey MP, Carey PR, Bonomo RA, van den Akker F, J Biol Chem. 2005 Oct 14;280(41):34900-7. Epub 2005 Jul 29. PMID:16055923
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