9HH6 | pdb_00009hh6

Crystal Structure of Nsp15 Endoribonuclease from SARS CoV-2 in Complex with TAS-103


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.00 Å
  • R-Value Free: 
    0.177 (Depositor), 0.182 (DCC) 
  • R-Value Work: 
    0.162 (Depositor), 0.169 (DCC) 
  • R-Value Observed: 
    0.162 (Depositor) 

  • Method: SOLUTION SCATTERING

Starting Model: experimental
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Ligand Structure Quality Assessment 


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Literature

Identification, validation, and characterization of approved and investigational drugs interfering with the SARS-CoV-2 endoribonuclease Nsp15.

Chatziefthymiou, S.D.Kuzikov, M.Afandi, S.Kovacs, G.Srivastava, S.Zaliani, A.Gruzinov, A.Pompidor, G.Lunelli, M.Ahmed, G.R.Labahn, J.Hakanpaa, J.Windshugel, B.Kolbe, M.

(2025) Protein Sci 34: e70156-e70156

  • DOI: https://doi.org/10.1002/pro.70156
  • Primary Citation of Related Structures:  
    9HH5, 9HH6

  • PubMed Abstract: 

    Since the emergence of SARS-CoV-2 at the end of 2019, the virus has caused significant global health and economic disruptions. Despite the rapid development of antiviral vaccines and some approved treatments such as remdesivir and paxlovid, effective antiviral pharmacological treatments for COVID-19 patients remain limited. This study explores Nsp15, a 3'-uridylate-specific RNA endonuclease, which has a critical role in immune system evasion and hence in escaping the innate immune sensors. We conducted a comprehensive drug repurposing screen and identified 44 compounds that showed more than 55% inhibition of Nsp15 activity in a real-time fluorescence assay. A validation pipeline was employed to exclude unspecific interactions, and dose-response assays confirmed 29 compounds with an IC 50 below 10 μM. Structural studies, including molecular docking and x-ray crystallography, revealed key interactions of identified inhibitors, such as TAS-103 and YM-155, with the Nsp15 active site and other critical regions. Our findings show that the identified compounds, particularly those retaining potency under different assay conditions, could serve as promising hits for developing Nsp15 inhibitors. Additionally, the study emphasizes the potential of combination therapies targeting multiple viral processes to enhance treatment efficacy and reduce the risk of drug resistance. This research contributes to the ongoing efforts to develop effective antiviral therapies for SARS-CoV-2 and possibly other coronaviruses.


  • Organizational Affiliation

    Photon Science, DESY, Hamburg, Germany.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
ORF1ab polyprotein347Severe acute respiratory syndrome coronavirus 2Mutation(s): 0 
Gene Names: ORF1ab
UniProt
Find proteins for A0A8B6RHF8 (Severe acute respiratory syndrome coronavirus 2)
Explore A0A8B6RHF8 
Go to UniProtKB:  A0A8B6RHF8
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupA0A8B6RHF8
Sequence Annotations
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  • Reference Sequence
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 2
MoleculeChains Sequence LengthOrganismDetailsImage
ORF1ab polyprotein345Severe acute respiratory syndrome coronavirus 2Mutation(s): 0 
Gene Names: ORF1ab
UniProt
Find proteins for A0A8B1JY75 (Severe acute respiratory syndrome coronavirus 2)
Explore A0A8B1JY75 
Go to UniProtKB:  A0A8B1JY75
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupA0A8B1JY75
Sequence Annotations
Expand
  • Reference Sequence
Small Molecules
Ligands 3 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
A1IUV (Subject of Investigation/LOI)
Query on A1IUV

Download Ideal Coordinates CCD File 
C [auth A],
I [auth B]
6-[2-(dimethylamino)ethylamino]-3-oxidanyl-indeno[2,1-c]quinolin-7-one
C20 H19 N3 O2
ROWSTIYZUWEOMM-UHFFFAOYSA-N
PO4
Query on PO4

Download Ideal Coordinates CCD File 
D [auth A],
J [auth B]
PHOSPHATE ION
O4 P
NBIIXXVUZAFLBC-UHFFFAOYSA-K
EDO
Query on EDO

Download Ideal Coordinates CCD File 
E [auth A]
F [auth A]
G [auth A]
H [auth A]
K [auth B]
E [auth A],
F [auth A],
G [auth A],
H [auth A],
K [auth B],
L [auth B]
1,2-ETHANEDIOL
C2 H6 O2
LYCAIKOWRPUZTN-UHFFFAOYSA-N
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.00 Å
  • R-Value Free:  0.177 (Depositor), 0.182 (DCC) 
  • R-Value Work:  0.162 (Depositor), 0.169 (DCC) 
  • R-Value Observed: 0.162 (Depositor) 
  • Method: SOLUTION SCATTERING
Space Group: P 63
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 150.488α = 90
b = 150.488β = 90
c = 110.086γ = 120
Software Package:
Software NamePurpose
REFMACrefinement
Aimlessdata scaling
PHASERphasing
XDSdata reduction

Structure Validation

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Ligand Structure Quality Assessment 


Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
Other governmentGermanyDESY Strategy Fund

Revision History  (Full details and data files)

  • Version 1.0: 2025-05-28
    Type: Initial release