Download MendeleyNMR crystallography reveals active-site protonation states of Toho-1 beta-lactamase in complex with avibactam.
Williams, C.G., Wang, S., Carta, V., Langan, P.S., Thome, A.F., Ramos, S.A., Holmes, J.B., Ghosh, R.K., Weiss, K.L., Beran, G.J.O., Hartman, J.D., Coates, L., Rienstra, C.M., Mueller, L.J.(2026) Proc Natl Acad Sci U S A 123: e2616547123-e2616547123
- PubMed: 42743273 Search on PubMedSearch on PubMed Central
- DOI: https://doi.org/10.1073/pnas.2616547123
- Primary Citation Related Structures:
9ZO2, 9ZOZ, 9ZQQ - PubMed Abstract:
The determination of active-site protonation states is critical for a full mechanistic understanding of enzyme catalysis and inhibition. Here, we employ NMR crystallography-the integrated combination of solid-state NMR spectroscopy, X-ray diffraction, and first-principles computational chemistry-to determine the protonation states of the active site of Toho-1 β-lactamase in complex with the non-β-lactam inhibitor avibactam. We report two X-ray crystal structures of the Toho-1:avibactam complex, along with high-field solid-state NMR measurements that enable near-complete backbone and side-chain resonance assignments. To overcome the computational scaling limits that have traditionally hindered NMR crystallography in large systems, we use an accelerated workflow in which machine-learning interatomic potentials enable efficient geometry refinement prior to density functional theory chemical shift calculations. For Toho-1, quantitative analysis of the active-site chemical shifts and chemical shift tensors using this hybrid protocol reveals that the key active-site side chains retain their canonical charge states in the presence of avibactam, with Lys73 and Lys234 protonated and positively charged, and Glu166 deprotonated and poised to function as a general base. Contrary to recent proposals suggesting that avibactam inhibits by suppressing essential proton transfers through p K a perturbations, our data point to a more direct chemical origin arising from the intrinsic resistance of the Ser70-avibactam carbamoyl linkage to hydrolysis.
- Department of Chemistry, University of California-Riverside, Riverside, CA 92521.
Organizational Affiliation:
