Solution structure, dynamics and fragment binding of unbound MERS-CoV nsp10
- 1University College London
Abstract
Middle East Respiratory Syndrome Coronavirus (MERS-CoV) poses a significant public health threat, with a fatality rate of 37% and no approved therapeutics. Non-structural protein 10 (nsp10) is an essential cofactor that activates both the nsp14 3'-5' exoribonuclease (ExoN) activity required for RNA proofreading and the nsp16 2'-O-methyltransferase (2'-O-MTase) implicated in viral RNA cap formation. Despite its functional importance, the unbound structure and dynamics of MERS-CoV nsp10 in solution remain uncharacterised. Here we report a near-complete NMR backbone and sidechain assignment and characterise the solution structure and dynamics of the protein by NMR. In contrast to the folded 1 helix observed in crystal structures of coronavirus nsp10, we find that this region is intrinsically disordered in solution, with residues 10-22 undetectable under standard conditions and further evidenced by pH titration, temperature-dependent NMR, and CLEANEX-PM experiments. Analysis of NOE contacts confirmed that the core adopts the conserved coronavirus nsp10 fold, consistent with the AlphaFold-predicted structure. 15N backbone relaxation measurements indicated a rigid, well-ordered core with only localised flexibility, despite a relatively low proportion of secondary structure elements, and CPMG and CEST experiments detected no conformational exchange on the s-ms timescale. Building on this structural and dynamic characterisation, we explored the ligandability of nsp10 by 19F NMR fragment screening. Screening of a 463-compound library identified 23 initial hits (4.97% hit rate), of which 20 were confirmed by 15N SOFAST-HMQC and eight gave quantifiable affinities by MST (Kd 0.5-6.9 mM), the remainder being too weak for reliable determination. Chemical shift perturbations clustered near functional surfaces of the folded core, indicating that MERS-CoV nsp10 is ligandable and providing chemical starting points for antiviral development.
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BibTeX
@misc{dong2026solution,
title = {{Solution structure, dynamics and fragment binding of unbound MERS-CoV nsp10}},
author = {D. Dong and F. G. Kozielski and C. A. Waudby},
howpublished = {bioRxiv},
year = {2026},
month = sep,
doi = {10.64898/2026.09.24.754126},
url = {https://www.biorxiv.org/content/10.64898/2026.09.24.754126v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Solution structure, dynamics and fragment binding of unbound MERS-CoV nsp10
AU - D. Dong
AU - F. G. Kozielski
AU - C. A. Waudby
PY - 2026
DA - 2026/09/24
PB - bioRxiv
DO - 10.64898/2026.09.24.754126
UR - https://www.biorxiv.org/content/10.64898/2026.09.24.754126v1
AB - Middle East Respiratory Syndrome Coronavirus (MERS-CoV) poses a significant public health threat, with a fatality rate of 37% and no approved therapeutics. Non-structural protein 10 (nsp10) is an essential cofactor that activates both the nsp14 3'-5' exoribonuclease (ExoN) activity required for RNA proofreading and the nsp16 2'-O-methyltransferase (2'-O-MTase) implicated in viral RNA cap formation. Despite its functional importance, the unbound structure and dynamics of MERS-CoV nsp10 in solution remain uncharacterised. Here we report a near-complete NMR backbone and sidechain assignment and characterise the solution structure and dynamics of the protein by NMR. In contrast to the folded 1 helix observed in crystal structures of coronavirus nsp10, we find that this region is intrinsically disordered in solution, with residues 10-22 undetectable under standard conditions and further evidenced by pH titration, temperature-dependent NMR, and CLEANEX-PM experiments. Analysis of NOE contacts confirmed that the core adopts the conserved coronavirus nsp10 fold, consistent with the AlphaFold-predicted structure. 15N backbone relaxation measurements indicated a rigid, well-ordered core with only localised flexibility, despite a relatively low proportion of secondary structure elements, and CPMG and CEST experiments detected no conformational exchange on the s-ms timescale. Building on this structural and dynamic characterisation, we explored the ligandability of nsp10 by 19F NMR fragment screening. Screening of a 463-compound library identified 23 initial hits (4.97% hit rate), of which 20 were confirmed by 15N SOFAST-HMQC and eight gave quantifiable affinities by MST (Kd 0.5-6.9 mM), the remainder being too weak for reliable determination. Chemical shift perturbations clustered near functional surfaces of the folded core, indicating that MERS-CoV nsp10 is ligandable and providing chemical starting points for antiviral development.
ER -