9TMP | pdb_00009tmp

Crystal Structure of Native Cytochrome b562 in complex with the synthetic anti-BRIL antibody BAG2.

• PDB DOI: https://doi.org/10.2210/pdb9TMP/pdb

• Classification: PROTEIN BINDING
• Organism(s): Escherichia coli BL21, synthetic construct
• Expression System: Escherichia coli
• Mutation(s): No 


• Deposited: 2025-12-15 Released: 2026-03-25 
• Deposition Author(s): Cooper, B.F., Isom, G.L.
• Funding Organization(s): Medical Research Council (MRC, United Kingdom), European Research Council (ERC)

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Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 2.65 Å
• R-Value Free: 
  0.237 (Depositor), 0.237 (DCC) 
• R-Value Work: 
  0.207 (Depositor), 0.209 (DCC) 
• R-Value Observed: 
  0.209 (Depositor) 

Starting Model: experimental

Literature

Optimized bacterial expression of a synthetic BRIL antibody.

Cooper, B.F., Isom, G.L.

(2026) Acta Crystallogr F Struct Biol Commun 

• PubMed: 41842660 
• DOI: https://doi.org/10.1107/S2053230X26001548
• Primary Citation Related Structures: 
  9TMP


• PubMed Abstract: 
  

  The use of monoclonal fragments antigen binding (Fabs) is a prevalent methodology facilitating protein structure determination via both crystallography and cryo-EM. The development of a synthetic Fab against the BRIL domain improved the accessibility of this approach, providing a general fiducial applicable to any protein of interest via the simple curation of a BRIL fusion protein. Here, we document the generation of a T7 Express ΔcybC strain allowing contaminant-free bacterial expression of the synthetic anti-BRIL Fab BAG2. We also report the crystal structure of BAG2 in complex with native cytochrome b ₅₆₂ , a complex arising from expression in canonical Escherichia coli strains.

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Organizational Affiliation: 
• Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, United Kingdom.

Biological Assembly 1  

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Hetero 3-mer - A1B1C1 

Biological assembly 1 assigned by authors.

Biological Assembly Evidence: gel filtration

Macromolecule Content 

• Total Structure Weight: 62.5 kDa 
• Atom Count: 4,150 
• Modeled Residue Count: 542 
• Deposited Residue Count: 572 
• Unique protein chains: 3

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
Soluble cytochrome b562	A	128	Escherichia coli BL21	Mutation(s): 0
UniProt
Find proteins for P0ABE7 (Escherichia coli) Explore P0ABE7  Go to UniProtKB:  P0ABE7

Entity ID: 2
Molecule	Chains	Sequence Length	Organism	Details	Image
anti-BRIL antibody - heavy chain	B [auth H]	229	synthetic construct	Mutation(s): 0

Entity ID: 3
Molecule	Chains	Sequence Length	Organism	Details	Image
anti-BRIL antibody - light chain	C [auth L]	215	synthetic construct	Mutation(s): 0

Small Molecules

Ligands 1 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
HEM (Subject of Investigation/LOI)	D [auth A]	PROTOPORPHYRIN IX CONTAINING FE C34 H32 Fe N4 O4 KABFMIBPWCXCRK-RGGAHWMASA-L

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 2.65 Å
• R-Value Free:  0.237 (Depositor), 0.237 (DCC) 
• R-Value Work:  0.207 (Depositor), 0.209 (DCC) 
• R-Value Observed: 0.209 (Depositor) 

Space Group: P 6₅

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 88.73	α = 90
b = 88.73	β = 90
c = 162.53	γ = 120

Software Package:

Software Name	Purpose
PHENIX	refinement
xia2	data reduction
DIALS	data scaling
PHASER	phasing

Structure Validation

Entry History & Funding Information

Deposition Data

• Released Date: 2026-03-25 
Deposition Author(s): Cooper, B.F., Isom, G.L.

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Funding Organization	Location	Grant Number
Medical Research Council (MRC, United Kingdom)	United Kingdom	MR/W016672/1
European Research Council (ERC)	European Union	101162143

Revision History  

• Version 1.0: 2026-03-25
  Type: Initial release
  
• Version 1.1: 2026-04-01
  Changes: Database references