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 36KK | pdb_000036kk

Crystal structure of Danio rerio histone deacetylase 6 catalytic domain 2 in complex with spirocyclic inhibitor 14


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.10 Å
  • R-Value Free: 
    0.240 (Depositor), 0.239 (DCC) 
  • R-Value Work: 
    0.211 (Depositor), 0.211 (DCC) 
  • R-Value Observed: 
    0.213 (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 1.0 of the entry. See complete history. 

Literature

Structure-Based Design of HDAC6 Inhibitors Targeting the L2 Pocket: Modulating Autophagy and Liquid-Liquid Phase Separation in Lung Cancer.

Barone, S., Eafa, A., Bello, I., Filocamo, G., Alberico, A., Cassese, E., Guadagni, A., Rebmann, H., Cosentino, E., Stollmaier, J.G., Miller, A.K., Summa, V., Wang, L., Panza, E., Christianson, D.W., Brindisi, M.

(2026) J Med Chem 69: 24495-24522

  • DOI: https://doi.org/10.1021/acs.jmedchem.6c02004
  • Primary Citation Related Structures: 
    36KH, 36KI, 36KJ, 36KK, 36KL, 36KM

  • PubMed Abstract: 

    We herein describe the structure-based design, synthesis and biological evaluation of a new class of histone deacetylase 6 (HDAC6) inhibitors guided by X-ray crystal structures of our previously identified compounds 13-15. X-ray co-crystal structures of second-generation inhibitors 19b (Subseries I) and 20b (Subseries II) within zHDAC6 CD2 confirmed that these compounds behave as highly potent HDAC6 inhibitors with the ability to engage the S531 residue in the L2 loop HDAC6 catalytic domain. Western-blot analysis confirmed the target engagement in cell-based settings, through the increase of acetylated tubulin levels, without significant variation in the histone acetylation status. Compound 20b extensively reduced the viability of A549 cells in both 2- and 3-dimensional cell cultures, through the activation of pro-autophagic pathways. In addition, HDAC6 inhibition impaired the nucleation of stress-granules, confirming the ability of these compounds to modulate liquid-liquid phase separation, an emerging HDAC6-driven hallmark in cancer.


  • Organizational Affiliation: 
    • Department of Pharmacy, Department of Excellence 2023-2027, University of Naples Federico II, Via D. Montesano 49, 80131Naples, Italy.

Macromolecule Content 

  • Total Structure Weight: 238.42 kDa 
  • Atom Count: 5,671 
  • Modeled Residue Count: 703 
  • Deposited Residue Count: 2,162 
  • Unique protein chains: 1

Macromolecules

Find similar proteins by:|  3D Structure
Entity ID: 1
MoleculeChains  Sequence LengthOrganismDetailsImage
Protein deacetylase HDAC6
A, B
1,081Danio rerioMutation(s): 0 
Gene Names: hdac6
Entity Groups
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
Sequence Annotations
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Reference Sequence

Small Molecules

Ligands 4 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
A1DKB
(Subject of Investigation/LOI)

Query on A1DKB



Download:Ideal Coordinates CCD File
C [auth A],
H [auth B]
3-fluoro-N-hydroxy-4-({4-oxo-1-phenyl-8-[(pyridin-3-yl)methyl]-1,3,8-triazaspiro[4.5]decan-3-yl}methyl)benzamide
C27 H28 F N5 O3
FYNCIRXZCMNTRN-UHFFFAOYSA-N
ZN

Query on ZN



Download:Ideal Coordinates CCD File
E [auth A],
J [auth B]
ZINC ION
Zn
PTFCDOFLOPIGGS-UHFFFAOYSA-N
EDO

Query on EDO



Download:Ideal Coordinates CCD File
D [auth A],
I [auth B]
1,2-ETHANEDIOL
C2 H6 O2
LYCAIKOWRPUZTN-UHFFFAOYSA-N
K

Query on K



Download:Ideal Coordinates CCD File
F [auth A],
G [auth A],
K [auth B],
L [auth B]
POTASSIUM ION
K
NPYPAHLBTDXSSS-UHFFFAOYSA-N

Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.10 Å
  • R-Value Free:  0.240 (Depositor), 0.239 (DCC) 
  • R-Value Work:  0.211 (Depositor), 0.211 (DCC) 
  • R-Value Observed: 0.213 (Depositor) 
Space Group: P 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 48.178α = 68.797
b = 55.402β = 87.471
c = 75.855γ = 83.06
Software Package:
Software NamePurpose
PHENIXrefinement
autoPROCdata processing

Structure Validation

View Full Validation Report



Ligand Structure Quality Assessment 


Entry History 

& Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)United StatesGM49758

Revision History  (Full details and data files)

  • Version 1.0: 2026-11-11
    Type: Initial release