3SJ5

I5F Mutant Structure of T. Tengcongensis H-NOX

Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.67 Å
  • R-Value Free: 0.247 
  • R-Value Work: 0.197 
  • R-Value Observed: 0.200 

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Literature

Controlling Conformational Flexibility of an O2-Binding H-NOX Domain.

Weinert, E.E., Phillips-Piro, C.M., Tran, R., Mathies, R.A., Marletta, M.A.

(2011) Biochemistry 50: 6832-6840

  • DOI: 10.1021/bi200788x
  • Primary Citation of Related Structures:  
    3SJ5

  • PubMed Abstract: 

    • Heme Nitric oxide/OXygen binding (H-NOX) domains have provided a novel scaffold to probe ligand affinity in hemoproteins. Mutation of isoleucine 5, a conserved residue located in the heme-binding pocket of the H-NOX domain from Thermoanaerobacter tengcongensis (Tt H-NOX), was carried out to examine changes in oxygen (O(2))-binding properties ...

    Heme Nitric oxide/OXygen binding (H-NOX) domains have provided a novel scaffold to probe ligand affinity in hemoproteins. Mutation of isoleucine 5, a conserved residue located in the heme-binding pocket of the H-NOX domain from Thermoanaerobacter tengcongensis (Tt H-NOX), was carried out to examine changes in oxygen (O(2))-binding properties. A series of I5 mutants (I5F, I5F/I75F, I5F/L144F, I5F/I75F/L144F) were investigated to probe the role of steric bulk within the heme pocket. The mutations significantly increased O(2) association rates (1.5-2.5-fold) and dissociation rates (8-190-fold) as compared to wild-type Tt H-NOX. Structural changes that accompanied the I5F mutation were characterized using X-ray crystallography and resonance Raman spectroscopy. A 1.67 Å crystal structure of the I5F mutant indicated that introducing a phenylalanine at position 5 resulted in a significant shift of the N-terminal domain of the protein, causing an opening of the heme pocket. This movement also resulted in an increased amount of flexibility at the N-terminus and the loop covering the N-terminal helix as indicated by the two conformations of the first six N-terminal amino acids, high B-factors in this region of the protein, and partially discontinuous electron density. In addition, introduction of a phenylalanine at position 5 resulted in increased flexibility of the heme within the pocket and weakened hydrogen bonding to the bound O(2) as measured by resonance Raman spectroscopy. This study provides insight into the critical role of I5 in controlling conformational flexibility and ligand affinity in H-NOX proteins.

    Organizational Affiliation: 

    Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, United States.



Macromolecules
Find similar proteins by: 
(by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Methyl-accepting chemotaxis proteinA, B188Caldanaerobacter subterraneus subsp. tengcongensisMutation(s): 1 
Gene Names: Tar4, TTE0680
UniProt
Find proteins for Q8RBX6 (Caldanaerobacter subterraneus subsp. tengcongensis (strain DSM 15242 / JCM 11007 / NBRC 100824 / MB4))
Explore Q8RBX6 
Go to UniProtKB:  Q8RBX6
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ8RBX6
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
HEM
Query on HEM
Download Ideal Coordinates CCD File 
C [auth A],
D [auth B]		PROTOPORPHYRIN IX CONTAINING FE
C34 H32 Fe N4 O4
KABFMIBPWCXCRK-RGGAHWMASA-L		 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.67 Å
  • R-Value Free: 0.247 
  • R-Value Work: 0.197 
  • R-Value Observed: 0.200 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 44.585α = 90
b = 67.116β = 92.01
c = 66.428γ = 90
Software Package:
Software NamePurpose
HKL-2000data collection
PHASERphasing
PHENIXrefinement
HKL-2000data reduction
HKL-2000data scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2011-07-20
    Type: Initial release
  • Version 1.1: 2011-08-24
    Changes: Database references
  • Version 1.2: 2017-10-25
    Changes: Author supporting evidence