4ND8

Av Nitrogenase MoFe Protein High pH Form


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.00 Å
  • R-Value Free: 0.204 
  • R-Value Work: 0.156 
  • R-Value Observed: 0.159 

Starting Model: experimental
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This is version 1.2 of the entry. See complete history


Literature

Turnover-Dependent Inactivation of the Nitrogenase MoFe-Protein at High pH.

Yang, K.Y.Haynes, C.A.Spatzal, T.Rees, D.C.Howard, J.B.

(2014) Biochemistry 53: 333-343

  • DOI: https://doi.org/10.1021/bi4014769
  • Primary Citation of Related Structures:  
    4ND8

  • PubMed Abstract: 

    Proton uptake accompanies the reduction of all known substrates by nitrogenase. As a consequence, a higher pH should limit the availability of protons as a substrate essential for turnover, thereby increasing the proportion of more highly reduced forms of the enzyme for further study. The utility of the high-pH approach would appear to be problematic in view of the observation reported by Pham and Burgess [(1993) Biochemistry 32, 13725-13731] that the MoFe-protein undergoes irreversible protein denaturation above pH 8.65. In contrast, we found by both enzyme activity and crystallographic analyses that the MoFe-protein is stable when incubated at pH 9.5. We did observe, however, that at higher pHs and under turnover conditions, the MoFe-protein is slowly inactivated. While a normal, albeit low, level of substrate reduction occurs under these conditions, the MoFe-protein undergoes a complex transformation; initially, the enzyme is reversibly inhibited for substrate reduction at pH 9.5, yet in a second, slower process, the MoFe-protein becomes irreversibly inactivated as measured by substrate reduction activity at the optimal pH of 7.8. The final inactivated MoFe-protein has an increased hydrodynamic radius compared to that of the native MoFe-protein, yet it has a full complement of iron and molybdenum. Significantly, the modified MoFe-protein retains the ability to specifically interact with its nitrogenase partner, the Fe-protein, as judged by the support of ATP hydrolysis and by formation of a tight complex with the Fe-protein in the presence of ATP and aluminum fluoride. The turnover-dependent inactivation coupled to conformational change suggests a mechanism-based transformation that may provide a new probe of nitrogenase catalysis.


  • Organizational Affiliation

    Division of Chemistry and Chemical Engineering 114-96, California Institute of Technology , Pasadena, California 91125, United States.


Macromolecules
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Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Nitrogenase molybdenum-iron protein alpha chain
A, C
492Azotobacter vinelandiiMutation(s): 0 
EC: 1.18.6.1
UniProt
Find proteins for P07328 (Azotobacter vinelandii)
Explore P07328 
Go to UniProtKB:  P07328
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP07328
Sequence Annotations
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  • Reference Sequence
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 2
MoleculeChains Sequence LengthOrganismDetailsImage
Nitrogenase molybdenum-iron protein beta chain
B, D
523Azotobacter vinelandiiMutation(s): 0 
EC: 1.18.6.1
UniProt
Find proteins for P07329 (Azotobacter vinelandii)
Explore P07329 
Go to UniProtKB:  P07329
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP07329
Sequence Annotations
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  • Reference Sequence
Small Molecules
Ligands 4 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
ICS
Query on ICS

Download Ideal Coordinates CCD File 
F [auth A],
J [auth C]
iron-sulfur-molybdenum cluster with interstitial carbon
C Fe7 Mo S9
DDQFAOMIVKLFON-UHFFFAOYSA-N
1CL
Query on 1CL

Download Ideal Coordinates CCD File 
G [auth A],
K [auth C]
FE(8)-S(7) CLUSTER, OXIDIZED
Fe8 S7
JKVMXLBGZBULKV-UHFFFAOYSA-N
HCA
Query on HCA

Download Ideal Coordinates CCD File 
E [auth A],
I [auth C]
3-HYDROXY-3-CARBOXY-ADIPIC ACID
C7 H10 O7
XKJVEVRQMLKSMO-SSDOTTSWSA-N
FE
Query on FE

Download Ideal Coordinates CCD File 
H [auth B],
L [auth D]
FE (III) ION
Fe
VTLYFUHAOXGGBS-UHFFFAOYSA-N
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.00 Å
  • R-Value Free: 0.204 
  • R-Value Work: 0.156 
  • R-Value Observed: 0.159 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 76.527α = 90
b = 127.915β = 108.9
c = 107.082γ = 90
Software Package:
Software NamePurpose
SCALAdata scaling
PHASERphasing
PHENIXrefinement
PDB_EXTRACTdata extraction
Blu-Icedata collection
XDSdata reduction
MOLREPphasing

Structure Validation

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Ligand Structure Quality Assessment 


Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2014-01-15
    Type: Initial release
  • Version 1.1: 2014-02-05
    Changes: Database references
  • Version 1.2: 2023-09-20
    Changes: Data collection, Database references, Derived calculations, Refinement description