21TK | pdb_000021tk

Enterovirus 71 Polymerase (S417G mutant) Elongation Complex with Two Remdesivir Nucleotides Posing between Product Strand Positions -4/-5 and -6/-7, respectively (C3S6 form)

• PDB DOI: https://doi.org/10.2210/pdb21TK/pdb
• NAKB: 21TK

• Classification: TRANSFERASE
• Organism(s): Enterovirus A71, synthetic construct
• Expression System: Escherichia coli BL21(DE3)
• Mutation(s): Yes 


• Deposited: 2025-12-23 Released: 2026-10-07 
• Deposition Author(s): Li, R., Gong, P.
• Funding Organization(s): Ministry of Science and Technology (MoST, China)

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Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 1.90 Å
• R-Value Free: 
  0.225 (Depositor), 0.224 (DCC) 
• R-Value Work: 
  0.193 (Depositor), 0.193 (DCC) 
• R-Value Observed: 
  0.194 (Depositor) 

Starting Model: experimental

Literature

Highly effective viral RdRP translocation hindrance by the remdesivir nucleotide

Li, R., Shao, Q., Wang, M., Feng, C., Xu, Q., Wang, Q., Shang, L.

(2026) Nucleic Acids Res 

• DOI: https://doi.org/10.1093/nar/gkag957

Biological Assembly 1  

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Monomer - A1 

Biological assembly 1 assigned by authors and generated by PISA (software)

Biological Assembly Evidence: gel filtration

Macromolecule Content 

• Total Structure Weight: 70.43 kDa 
• Atom Count: 4,568 
• Modeled Residue Count: 486 
• Deposited Residue Count: 520 
• Unique protein chains: 1
• Unique nucleic acid chains: 2

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
Enterovirus 71 polymerase	A	468	Enterovirus A71	Mutation(s): 2  EC: 3.4.22.29 (PDB Primary Data), 3.6.1.15 (PDB Primary Data), 3.4.22.28 (PDB Primary Data), 2.7.7.48 (PDB Primary Data)
UniProt
Find proteins for E5RPG3 (Human enterovirus 71) Explore E5RPG3  Go to UniProtKB:  E5RPG3

Entity ID: 2
Molecule	Chains	Length	Organism	Image
RNA (34-MER)	B	34	synthetic construct

Entity ID: 3
Molecule	Chains	Length	Organism	Image
RNA (5'-R(*UP*GP*UP*UP*CP*GP*AP*CP*GP*AP*G*(F86)P*G*(F86)P*GP*CP*CP*U)-3')	C	18	synthetic construct

Small Molecules

Ligands 2 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
SO4	E [auth A], F [auth A]	SULFATE ION O4 S QAOWNCQODCNURD-UHFFFAOYSA-L
ZN	D [auth A]	ZINC ION Zn PTFCDOFLOPIGGS-UHFFFAOYSA-N

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 1.90 Å
• R-Value Free:  0.225 (Depositor), 0.224 (DCC) 
• R-Value Work:  0.193 (Depositor), 0.193 (DCC) 
• R-Value Observed: 0.194 (Depositor) 

Space Group: P 2₁ 2₁ 2₁

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 62.234	α = 90
b = 76.793	β = 90
c = 154.908	γ = 90

Software Package:

Software Name	Purpose
PHENIX	refinement
HKL-2000	data scaling
HKL-2000	data reduction
PHASER	phasing
PDB_EXTRACT	data extraction

Structure Validation

Entry History 

& Funding Information

Deposition Data

• Released Date: 2026-10-07 
Deposition Author(s): Li, R., Gong, P.

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Funding Organization	Location	Grant Number
Ministry of Science and Technology (MoST, China)	China	2022YFC2303300

Revision History  

• Version 1.0: 2026-10-07
  Type: Initial release