1nym
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Crystal Structure of the complex between M182T mutant of TEM-1 and a boronic acid inhibitor (CXB)
OverviewOverview
Developing antimicrobials that are less likely to engender resistance has, become an important design criterion as more and more drugs fall victim to, resistance mutations. One hypothesis is that the more closely an inhibitor, resembles a substrate, the more difficult it will be to develop resistant, mutations that can at once disfavor the inhibitor and still recognize the, substrate. To investigate this hypothesis, 10 transition-state analogues, of greater or lesser similarity to substrates, were tested for inhibition, of TEM-1 beta-lactamase, the most widespread resistance enzyme to, penicillin antibiotics. The inhibitors were also tested against four, characteristic mutant enzymes: TEM-30, TEM-32, TEM-52, and TEM-64. The, inhibitor most similar to the substrate, compound 10, was the most potent, inhibitor of the WT enzyme, with a K(i) value of 64 nM. Conversely, compound 10 was the most susceptible to the TEM-30 (R244S) mutant, for, which inhibition dropped by over 100-fold. The other inhibitors were, relatively impervious to the TEM-30 mutant enzyme. To understand, recognition and resistance to these transition-state analogues, the, structures of four of these inhibitors in complex with TEM-1 were, determined by X-ray crystallography. These structures suggest a structural, basis for distinguishing inhibitors that mimic the acylation transition, state and those that mimic the deacylation transition state; they also, suggest how TEM-30 reduces the affinity of compound 10. In cell culture, this inhibitor reversed the resistance of bacteria to ampicillin, reducing, minimum inhibitory concentrations of this penicillin by between 4- and, 64-fold, depending on the strain of bacteria. Notwithstanding this, activity, the resistance of TEM-30, which is already extant in the clinic, suggests that there can be resistance liabilities with substrate-based, design.
About this StructureAbout this Structure
1NYM is a Single protein structure of sequence from Escherichia coli with K, PO4 and CXB as ligands. Active as Beta-lactamase, with EC number 3.5.2.6 Full crystallographic information is available from OCA.
ReferenceReference
Recognition and resistance in TEM beta-lactamase., Wang X, Minasov G, Blazquez J, Caselli E, Prati F, Shoichet BK, Biochemistry. 2003 Jul 22;42(28):8434-44. PMID:12859188
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