9NN4 | pdb_00009nn4

BET BRD3-BD1 in complex with peptide 7.2

• PDB DOI: https://doi.org/10.2210/pdb9NN4/pdb

• Classification: TRANSCRIPTION
• Organism(s): Homo sapiens, synthetic construct
• Expression System: Escherichia coli BL21(DE3)
• Mutation(s): No 


• Deposited: 2025-03-05 Released: 2026-02-11 
• Deposition Author(s): Jing, X., Mackay, J.P.
• Funding Organization(s): National Health and Medical Research Council (NHMRC, Australia)

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Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 1.37 Å
• R-Value Free: 
  0.195 (Depositor), 0.196 (DCC) 
• R-Value Work: 
  0.156 (Depositor), 0.157 (DCC) 
• R-Value Observed: 
  0.158 (Depositor) 

Starting Model: experimental

Literature

The effect of peptide size on target affinity in mRNA display-derived macrocyclic peptides.

Jing, X., Suh, J., Maxwell, J., Patel, K., Norman, A., Reid, X.J., Deshpande, C., Low, J.K.K., Payne, R.J., Passioura, T., Mackay, J.P.

(2026) Chem Commun (Camb) 62: 4028-4031

• PubMed: 41614404 
• DOI: https://doi.org/10.1039/d5cc06167a
• Primary Citation Related Structures: 
  9NN3, 9NN4, 9NN5, 9NNT


• PubMed Abstract: 
  

  The large size of macrocyclic peptides discovered by mRNA display can hinder therapeutic development. Using size-restricted RaPID libraries and analysis of 40 published datasets, we show that potent binders are more reliably identified from libraries with at least nine randomised residues, providing guidance for mRNA display screen design.

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Organizational Affiliation: 
• School of Life and Environmental Sciences, University of Sydney, NSW 2006, Australia. [e-mail].
School of Chemistry, University of Sydney, NSW 2006, Australia. [e-mail].
Insamo South Pty Ltd, Chippendale, NSW, 2008, Australia.

Biological Assembly 1  

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Hetero 2-mer - A1B1 

Biological assembly 1 assigned by authors.

Biological Assembly Evidence: surface plasmon resonance

Biological Assembly 2  

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Hetero 2-mer - A1B1 

Biological assembly 2 assigned by authors.

Macromolecule Content 

• Total Structure Weight: 31.2 kDa 
• Atom Count: 2,533 
• Modeled Residue Count: 251 
• Deposited Residue Count: 262 
• Unique protein chains: 2

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
Bromodomain-containing protein 3	A, B	120	Homo sapiens	Mutation(s): 0  Gene Names: BRD3, KIAA0043, RING3L
UniProt & NIH Common Fund Data Resources
Find proteins for Q15059 (Homo sapiens) Explore Q15059  Go to UniProtKB:  Q15059
PHAROS:  Q15059 GTEx:  ENSG00000169925

Entity ID: 2
Molecule	Chains	Sequence Length	Organism	Details	Image
peptide 7.2	C [auth D], D [auth E]	11	synthetic construct	Mutation(s): 0

Small Molecules

Modified Residues  1 Unique
ID	Chains	Type	Formula	2D Diagram	Parent
ALY	C [auth D], D [auth E]	L-PEPTIDE LINKING	C8 H16 N2 O3		LYS

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 1.37 Å
• R-Value Free:  0.195 (Depositor), 0.196 (DCC) 
• R-Value Work:  0.156 (Depositor), 0.157 (DCC) 
• R-Value Observed: 0.158 (Depositor) 

Space Group: P 1 2₁ 1

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 68.826	α = 90
b = 30.067	β = 108.53
c = 77.854	γ = 90

Software Package:

Software Name	Purpose
PHENIX	refinement
SCALA	data scaling
PHENIX	phasing

Structure Validation

Entry History 

& Funding Information

Deposition Data

• Released Date: 2026-02-11 
Deposition Author(s): Jing, X., Mackay, J.P.

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Funding Organization	Location	Grant Number
National Health and Medical Research Council (NHMRC, Australia)	Australia	--

Revision History  

• Version 1.0: 2026-02-11
  Type: Initial release
  
• Version 1.1: 2026-03-04
  Changes: Database references