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 9I2Y | pdb_00009i2y

Human DHODH in Complex with QC6352


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.95 Å
  • R-Value Free: 
    0.198 (Depositor), 0.213 (DCC) 
  • R-Value Work: 
    0.178 (Depositor), 0.192 (DCC) 
  • R-Value Observed: 
    0.179 (Depositor) 

Starting Model: experimental
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wwPDB Validation 3D Report Full Report

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Ligand Structure Quality Assessment 


This is version 1.1 of the entry. See complete history. 

Literature

DHODH is the key target of the KDM4 inhibitor QC6352 in glioblastoma stem cells.

Sterling, J.R., Holtsmark, J.R., Joun, G.L., Graus, M.S., Du, T.Y., Kuchibhotla, M., Johns, T.G., deWeck, A., Loo, L., Neely, G.G., Tran, K., Shard, C., Gomez, G.A., Patil, A., Shi, D.D., Losman, J.A., Saxton, A.J., Baker, J.R., Lei, Z., Holland, M.T.O., Brennan, P.E., Francois, M., Kraemer, A., Mueller, S., Feng, Y., Workman, P., Munoz, L.

(2026) Nat Chem Biol 

  • DOI: https://doi.org/10.1038/s41589-026-02306-x
  • Primary Citation Related Structures: 
    9I2Y

  • PubMed Abstract: 

    Histone lysine demethylase 4 (KDM4) enzymes are frequently overexpressed in cancer and are considered to be promising therapeutic targets. QC6352, which is widely used as a best-in-class KDM4 chemical probe, shows potent antitumor activity across cancer models. Using comprehensive chemical biology approaches in glioblastoma models, we demonstrate that the efficacy of QC6352 and that of its clinical analog zavondemstat are independent of KDM4 inhibition. Instead, we identify dihydroorotate dehydrogenase (DHODH), a key enzyme in de novo pyrimidine biosynthesis, as the functional target driving their antiproliferative activity. Uridine supplementation and expression of an inhibitor-resistant DHODH mutant fully abrogate growth inhibition, whereas the orthogonal KDM4 inhibitor ML324, which lacks DHODH inhibition, fails to phenocopy QC6352. These findings establish QC6352 and zavondemstat as dual KDM4-DHODH inhibitors and identify DHODH inhibition as the dominant driver of their antiglioblastoma efficacy, as well as demonstrating the need for orthogonal chemical probes to accurately define drug mechanisms in cells.


  • Organizational Affiliation: 
    • School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia.

Macromolecule Content 

  • Total Structure Weight: 41.2 kDa 
  • Atom Count: 2,900 
  • Modeled Residue Count: 356 
  • Deposited Residue Count: 367 
  • Unique protein chains: 1

Macromolecules

Find similar proteins by:|  3D Structure
Entity ID: 1
MoleculeChains  Sequence LengthOrganismDetailsImage
Dihydroorotate dehydrogenase (quinone), mitochondrial367Homo sapiensMutation(s): 0 
Gene Names: DHODH
EC: 1.3.5.2
UniProt & NIH Common Fund Data Resources
Find proteins for Q02127 (Homo sapiens)
Explore Q02127 
Go to UniProtKB:  Q02127
PHAROS:  Q02127
GTEx:  ENSG00000102967 
Entity Groups
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ02127
Sequence Annotations
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Reference Sequence

Small Molecules

Ligands 5 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
FMN

Query on FMN



Download:Ideal Coordinates CCD File
H [auth A]FLAVIN MONONUCLEOTIDE
C17 H21 N4 O9 P
FVTCRASFADXXNN-SCRDCRAPSA-N
9DJ
(Subject of Investigation/LOI)

Query on 9DJ



Download:Ideal Coordinates CCD File
C [auth A]3-[({(1R)-6-[methyl(phenyl)amino]-1,2,3,4-tetrahydronaphthalen-1-yl}methyl)amino]pyridine-4-carboxylic acid
C24 H25 N3 O2
XSMABFRQESMONQ-SFHVURJKSA-N
ORO

Query on ORO



Download:Ideal Coordinates CCD File
G [auth A]OROTIC ACID
C5 H4 N2 O4
PXQPEWDEAKTCGB-UHFFFAOYSA-N
SO4

Query on SO4



Download:Ideal Coordinates CCD File
B [auth A],
E [auth A],
F [auth A]
SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L
ACT

Query on ACT



Download:Ideal Coordinates CCD File
D [auth A]ACETATE ION
C2 H3 O2
QTBSBXVTEAMEQO-UHFFFAOYSA-M

Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.95 Å
  • R-Value Free:  0.198 (Depositor), 0.213 (DCC) 
  • R-Value Work:  0.178 (Depositor), 0.192 (DCC) 
  • R-Value Observed: 0.179 (Depositor) 
Space Group: P 32 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 90.384α = 90
b = 90.384β = 90
c = 122.511γ = 120
Software Package:
Software NamePurpose
REFMACrefinement
Aimlessdata scaling
DIALSdata reduction
MOLREPphasing

Structure Validation

View Full Validation Report



Ligand Structure Quality Assessment 


Entry History 

& Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
Innovative Medicines InitiativeSwitzerland875510

Revision History  (Full details and data files)

  • Version 1.0: 2025-03-05
    Type: Initial release
  • Version 1.1: 2026-10-21
    Changes: Database references