7M5L

PCNA bound to peptide mimetic with linker


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.00 Å
  • R-Value Free: 0.275 
  • R-Value Work: 0.260 
  • R-Value Observed: 0.261 

Starting Model: experimental
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wwPDB Validation   3D Report Full Report


This is version 1.2 of the entry. See complete history


Literature

A cell permeable bimane-constrained PCNA-interacting peptide.

Horsfall, A.J.Vandborg, B.A.Kikhtyak, Z.Scanlon, D.B.Tilley, W.D.Hickey, T.E.Bruning, J.B.Abell, A.D.

(2021) RSC Chem Biol 2: 1499-1508

  • DOI: https://doi.org/10.1039/d1cb00113b
  • Primary Citation of Related Structures:  
    7M5L, 7M5M, 7M5N

  • PubMed Abstract: 

    The human sliding clamp protein known as proliferating cell nuclear antigen (PCNA) orchestrates DNA-replication and -repair and as such is an ideal therapeutic target for proliferative diseases, including cancer. Peptides derived from the human p21 protein bind PCNA with high affinity via a 3 10 -helical binding conformation and are known to shut down DNA-replication. Here, we present studies on short analogues of p21 peptides (143-151) conformationally constrained with a covalent linker between i , i + 4 separated cysteine residues at positions 145 and 149 to access peptidomimetics that target PCNA. The resulting macrocycles bind PCNA with K D values ranging from 570 nM to 3.86 μM, with the bimane-constrained peptide 7 proving the most potent. Subsequent X-ray crystallography and computational modelling studies of the macrocyclic peptides bound to PCNA indicated only the high-affinity peptide 7 adopted the classical 3 10 -helical binding conformation. This suggests the 3 10 -helical conformation is critical to high affinity PCNA binding, however NMR secondary shift analysis of peptide 7 revealed this secondary structure was not well-defined in solution. Peptide 7 is cell permeable and localised to the cell cytosol of breast cancer cells (MDA-MB-468), revealed by confocal microscopy showing blue fluorescence of the bimane linker. The inherent fluorescence of the bimane moiety present in peptide 7 allowed it to be directly imaged in the cell uptake assay, without attachment of an auxiliary fluorescent tag. This highlights a significant benefit of using a bimane constraint to access conformationally constrained macrocyclic peptides. This study identifies a small peptidomimetic that binds PCNA with higher affinity than previous reported p21 macrocycles, and is cell permeable, providing a significant advance toward development of a PCNA inhibitor for therapeutic applications.


  • Organizational Affiliation

    Institute of Photonics and Advanced Sensing (IPAS), The University of Adelaide Adelaide South Australia 5005 Australia john.bruning@adelaide.edu.au andrew.abell@adelaide.edu.au.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Proliferating cell nuclear antigen
A, B, C
258Homo sapiensMutation(s): 0 
Gene Names: PCNA
UniProt & NIH Common Fund Data Resources
Find proteins for P12004 (Homo sapiens)
Explore P12004 
Go to UniProtKB:  P12004
PHAROS:  P12004
GTEx:  ENSG00000132646 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP12004
Sequence Annotations
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  • Reference Sequence

Find similar proteins by:  Sequence   |   3D Structure  

Entity ID: 2
MoleculeChains Sequence LengthOrganismDetailsImage
Peptide mimetic (ACE)RQCSMTCFYHSK(NH2) with linkerD [auth E],
E [auth D],
F
14synthetic constructMutation(s): 0 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
Sequence Annotations
Expand
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.00 Å
  • R-Value Free: 0.275 
  • R-Value Work: 0.260 
  • R-Value Observed: 0.261 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 70.96α = 90
b = 84.468β = 90
c = 134.21γ = 90
Software Package:
Software NamePurpose
Aimlessdata scaling
PHENIXrefinement
PDB_EXTRACTdata extraction
XDSdata reduction
PHASERphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2021-08-11
    Type: Initial release
  • Version 1.1: 2021-11-10
    Changes: Database references
  • Version 1.2: 2023-10-18
    Changes: Data collection, Refinement description