8CRK

Crystal structure of N-terminal SARS-CoV-2 nsp1 in complex with fragment hit 7H2 refined against anomalous diffraction data

Replaces:  8AYW

Summary for 8CRK

• Entry DOI: 10.2210/pdb8crk/pdb
• Descriptor: Host translation inhibitor nsp1, (1~{R})-1-(4-chlorophenyl)ethanamine (3 entities in total)
• Functional Keywords: sars-cov-2, non-structural protein 1, fragment hit, anomalous diffraction, viral protein
• Biological source: Severe acute respiratory syndrome coronavirus 2
• Total number of polymer chains: 1
• Total formula weight: 13264.78

Authors

Ma, S.,Mikhailik, V.,Pinotsis, N.,Bowler, M.W.,Kozielski, F. (deposition date: 2023-03-08, release date: 2023-10-04)

Primary citation

Ma, S.,Mykhaylyk, V.,Bowler, M.W.,Pinotsis, N.,Kozielski, F.
High-Confidence Placement of Fragments into Electron Density Using Anomalous Diffraction-A Case Study Using Hits Targeting SARS-CoV-2 Non-Structural Protein 1.
Int J Mol Sci, 24:-, 2023

PubMed Abstract: The identification of multiple simultaneous orientations of small molecule inhibitors binding to a protein target is a common challenge. It has recently been reported that the conformational heterogeneity of ligands is widely underreported in the Protein Data Bank, which is likely to impede optimal exploitation to improve affinity of these ligands. Significantly less is even known about multiple binding orientations for fragments (<300 Da), although this information would be essential for subsequent fragment optimisation using growing, linking or merging and rational structure-based design. Here, we use recently reported fragment hits for the SARS-CoV-2 non-structural protein 1 (nsp1) N-terminal domain to propose a general procedure for unambiguously identifying binding orientations of 2-dimensional fragments containing either sulphur or chloro substituents within the wavelength range of most tunable beamlines. By measuring datasets at two energies, using a tunable beamline operating in vacuum and optimised for data collection at very low X-ray energies, we show that the anomalous signal can be used to identify multiple orientations in small fragments containing sulphur and/or chloro substituents or to verify recently reported conformations. Although in this specific case we identified the positions of sulphur and chlorine in fragments bound to their protein target, we are confident that this work can be further expanded to additional atoms or ions which often occur in fragments. Finally, our improvements in the understanding of binding orientations will also serve to improve the rational optimisation of SARS-CoV-2 nsp1 fragment hits.

PubMed: 37446375
DOI: 10.3390/ijms241311197

Experimental method

X-RAY DIFFRACTION (1.1 Å)