2AMO | pdb_00002amo

Loose Dimer of a Bacillus subtilis Nitric Oxide Synthase

• PDB DOI: https://doi.org/10.2210/pdb2AMO/pdb

• Classification: OXIDOREDUCTASE
• Organism(s): Bacillus subtilis
• Expression System: Escherichia coli BL21
• Mutation(s): No 


• Deposited: 2005-08-09 Released: 2006-10-31 
• Deposition Author(s): Pant, K., Crane, B.R.

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Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 2.60 Å
• R-Value Free: 
  0.290 (Depositor) 
• R-Value Work: 
  0.274 (Depositor) 
• R-Value Observed: 
  0.276 (Depositor) 

Starting Model: experimental

Literature

Structure of a loose dimer: an intermediate in nitric oxide synthase assembly.

Pant, K., Crane, B.R.

(2005) J Mol Biology 352: 932-940

• PubMed: 16126221 
• DOI: https://doi.org/10.1016/j.jmb.2005.07.070
• Primary Citation Related Structures: 
  2AMO, 2AN0, 2AN2


• PubMed Abstract: 
  

  Cooperativity among ligand binding, subunit association, and protein folding has implications for enzyme regulation as well as protein aggregation events associated with disease. The binding of substrate l-arginine or cofactor tetrahydrobiopterin converts nitric oxide synthases (NOSs) from a "loose dimer", with an exposed active center and higher sensitivity to proteolysis, to a "tight dimer" competent for catalysis. The crystallographic structure of the Bacillus subtilis NOS loose dimer shows an altered association state with severely destabilized subdomains. Ligand binding or heme reduction converts loose dimers to tight dimers in solution and crystals. Mutations at key positions in the dimer interface that distinguish prokaryotic from eukaryotic NOSs affect the propensity to form loose dimers. The loose dimer structure indicates that non-native interactions can mediate subunit association in NOS.

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Organizational Affiliation: 
• Department of Chemistry and Chemical Biology, Cornell University Ithaca, NY 14853, USA.

Biological Assembly 1  

Global Symmetry: Cyclic - C2  (Explore in 3D)
Global Stoichiometry: Homo 2-mer - A2 

Biological assembly 1 assigned by authors.

Biological Assembly 2  

Global Symmetry: Cyclic - C2  (Explore in 3D)
Global Stoichiometry: Homo 2-mer - A2 

Biological assembly 2 assigned by authors.

Macromolecule Content 

• Total Structure Weight: 84.19 kDa 
• Atom Count: 6,103 
• Modeled Residue Count: 724 
• Deposited Residue Count: 724 
• Unique protein chains: 1

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
Nitric oxide synthase oxygenase	A, B	362	Bacillus subtilis	Mutation(s): 0  Gene Names: nos EC: 1.14.13.39 (PDB Primary Data), 1.14.14.47 (UniProt)
UniProt
Find proteins for O34453 (Bacillus subtilis (strain 168)) Explore O34453  Go to UniProtKB:  O34453

Small Molecules

Ligands 1 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
HEM	C [auth A], D [auth B]	PROTOPORPHYRIN IX CONTAINING FE C34 H32 Fe N4 O4 KABFMIBPWCXCRK-RGGAHWMASA-L

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 2.60 Å
• R-Value Free:  0.290 (Depositor) 
• R-Value Work:  0.274 (Depositor) 
• R-Value Observed: 0.276 (Depositor) 

Space Group: P 2₁ 2₁ 2

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 81.314	α = 90
b = 93.211	β = 90
c = 118.546	γ = 90

Software Package:

Software Name	Purpose
REFMAC	refinement
HKL-2000	data reduction
SCALEPACK	data scaling
AMoRE	phasing

Structure Validation

Entry History 

Deposition Data

• Released Date: 2006-10-31 
Deposition Author(s): Pant, K., Crane, B.R.

Revision History  

• Version 1.0: 2006-10-31
  Type: Initial release
  
• Version 1.1: 2008-04-30
  Changes: Version format compliance
• Version 1.2: 2011-07-13
  Changes: Version format compliance
• Version 1.3: 2023-08-23
  Changes: Data collection, Database references, Derived calculations, Refinement description