Abstract
Organophosphorus (OP) compounds, including nerve agents and some pesticides, covalently bind to the catalytic serine of human acetylcholinesterase (hAChE), thereby inhibiting acetylcholine hydrolysis necessary for efficient neurotransmission. Oxime antidotes can reactivate the OP-conjugated hAChE, but reactivation efficiency can be low for pesticides, such as paraoxon (POX). Understanding structural and dynamic determinants of OP inhibition and reactivation can provide insights to design improved reactivators. Here, X-ray structures of hAChE with unaged POX, with POX and oximes MMB4 and RS170B, and with MMB4 are reported. A significant conformational distortion of the acyl loop was observed upon POX binding, being partially restored to the native conformation by oximes. Neutron vibrational spectroscopy combined with molecular dynamics simulations showed that picosecond vibrational dynamics of the acyl loop soften in the ∼20–50 cm−1 frequency range. The acyl loop structural perturbations may be correlated with its picosecond vibrational dynamics to yield more comprehensive template for structure-based reactivator design.
| Original language | English |
|---|---|
| Pages (from-to) | 1538-1549.e3 |
| Journal | Structure |
| Volume | 30 |
| Issue number | 11 |
| DOIs | |
| State | Published - Nov 3 2022 |
Funding
This research used resources at the Spallation Neutron Source and the High Flux Isotope Reactor, which are DOE Office of Science User Facilities operated by the Oak Ridge National Laboratory. The Office of Biological and Environmental Research supported research at ORNL’s Center for Structural Molecular Biology ( CSMB ), a DOE Office of Science User Facility. ORNL is managed by UT-Battelle LLC for DOE’s Office of Science, the single largest supporter of basic research in the physical sciences in the United States. The D 2 O used in this research was supplied by the United States Department of Energy Office of Science by the Isotope Program in the Office of Nuclear Physics. This research was supported by the CounterACT Program, National Institutes of Health Office of the Director (NIH OD), and the National Institute of Neurological Disorders and Stroke (NINDS), grant no. U01 NS083451 . This research used resources at the Spallation Neutron Source and the High Flux Isotope Reactor, which are DOE Office of Science User Facilities operated by the Oak Ridge National Laboratory. The Office of Biological and Environmental Research supported research at ORNL's Center for Structural Molecular Biology (CSMB), a DOE Office of Science User Facility. ORNL is managed by UT-Battelle LLC for DOE's Office of Science, the single largest supporter of basic research in the physical sciences in the United States. The D2O used in this research was supplied by the United States Department of Energy Office of Science by the Isotope Program in the Office of Nuclear Physics. This research was supported by the CounterACT Program, National Institutes of Health Office of the Director (NIH OD), and the National Institute of Neurological Disorders and Stroke (NINDS), grant no. U01 NS083451. Conceptualization, O.G. Z.R. and A.K.; methodology, X.C. Z.R. and A.K.; validation, O.G. M.F. and D.K.B.; investigation, O.G. and M.F.; visualization, O.G. M.F. X.C. and A.K.; writing – original draft, O.G. Z.R. M.F. X.C. and A.K.; writing – review & editing, X.C. Z.R. and A.K.; formal analysis, O.G. M.F. X.C. and D.K.B.; project administration, Z.R.; supervision, X.C. Z.R. and A.K.; funding acquisition, D.K.B. X.C. Z.R. and A.K. The authors declare no competing interests. While citing references scientifically relevant for this work, we also actively worked to promote gender balance in our reference list. We avoided “helicopter science” practices by including the participating local contributors from the region where we conducted the research as authors on the paper.
| Funders | Funder number |
|---|---|
| National Institutes of Health Office | |
| ORNL's Center for Structural Molecular Biology | |
| ORNL’s Center for Structural Molecular Biology | |
| United States Department of Energy Office of Science | |
| National Institute of Neurological Disorders and Stroke | U01NS083451 |
| Office of Disease Prevention | |
| Office of Science | |
| Biological and Environmental Research | |
| Nuclear Physics | |
| Oak Ridge National Laboratory | |
| Canadian Society for Molecular Biosciences | |
| UT-Battelle |
Keywords
- X-ray diffraction
- hAChE
- inelastic neutron scattering
- oxime reactivator
- paraoxon
- vibrational dynamics