1M1Y

Chemical Crosslink of Nitrogenase MoFe Protein and Fe Protein


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.2 Å
  • R-Value Free: 0.329 
  • R-Value Work: 0.279 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Biochemical and Structural Characterization of the Crosslinked Complex of Nitrogenase: Comparison to the ADP-AlF4- Stabilized Structure

Schmid, B.Einsle, O.Chiu, H.J.Willing, A.Yoshida, M.Howard, J.B.Rees, D.C.

(2002) Biochemistry 41: 15557-15565

  • Primary Citation of Related Structures:  1M34

  • PubMed Abstract: 
  • The transient formation of a complex between the component Fe- and MoFe-proteins of nitrogenase represents a central event in the substrate reduction mechanism of this enzyme. Previously, we have isolated an N-[3-(dimethylamino)propyl]-N'-ethylcarbod ...

    The transient formation of a complex between the component Fe- and MoFe-proteins of nitrogenase represents a central event in the substrate reduction mechanism of this enzyme. Previously, we have isolated an N-[3-(dimethylamino)propyl]-N'-ethylcarbodiimide (EDC) cross-linked complex of these proteins stabilized by a covalent isopeptide linkage between Glu 112 and Lys beta400 of the Fe-protein and MoFe-protein, respectively [Willing, A., et al. (1989) J. Biol. Chem. 264, 8499-8503; Willing, A., and Howard, J. B. (1990) J. Biol. Chem. 265, 6596-6599]. We report here the biochemical and structural characterization of the cross-linked complex to assess the mechanistic relevance of this species. Glycinamide inhibits the cross-linking reaction, and is found to be specifically incorporated into Glu 112 of the Fe-protein, without detectable modification of either of the neighboring residues (Glu 110 and Glu 111). This modified protein is still competent for substrate reduction, demonstrating that formation of the cross-linked complex is responsible for the enzymatic inactivation, and not the EDC reaction or the modification of the Fe-protein. Crystallographic analysis of the EDC-cross-linked complex at 3.2 A resolution confirms the site of the isopeptide linkage. The nature of the protein surfaces around the cross-linking site suggests there is a strong electrostatic component to the formation of the complex, although the interface area between the component proteins is small. The binding footprints between proteins in the cross-linked complex are adjacent, but with little overlap, to those observed in the complex of the nitrogenase proteins stabilized by ADP-AlF(4)(-). The results of these studies suggest that EDC cross-linking traps a nucleotide-independent precomplex of the nitrogenase proteins driven by complementary electrostatic interactions that subsequently rearranges in a nucleotide-dependent fashion to the electron transfer competent state observed in the ADP-AlF(4)(-) structure.


    Organizational Affiliation

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




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Nitrogenase molybdenum-iron protein alpha chain
A, C, I, K
491Azotobacter vinelandiiGene Names: nifD
EC: 1.18.6.1
Find proteins for P07328 (Azotobacter vinelandii)
Go to UniProtKB:  P07328
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
Nitrogenase molybdenum-iron protein beta chain
B, D, J, L
522Azotobacter vinelandiiGene Names: nifK
EC: 1.18.6.1
Find proteins for P07329 (Azotobacter vinelandii)
Go to UniProtKB:  P07329
Entity ID: 3
MoleculeChainsSequence LengthOrganismDetails
nitrogenase IRON protein 1
E, F, G, H, M, N, O, P
289Azotobacter vinelandiiGene Names: nifH1
EC: 1.18.6.1
Find proteins for P00459 (Azotobacter vinelandii)
Go to UniProtKB:  P00459
Small Molecules
Ligands 5 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
SF4
Query on SF4

Download SDF File 
Download CCD File 
E, G, N, P
IRON/SULFUR CLUSTER
Fe4 S4
LJBDFODJNLIPKO-VKOJMFJBAC
 Ligand Interaction
CFM
Query on CFM

Download SDF File 
Download CCD File 
A, C, I, K
FE-MO-S CLUSTER
Fe7 Mo S9
UZRXIPMKRKMLQF-VGXFRCDIAP
 Ligand Interaction
CA
Query on CA

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Download CCD File 
B, D, J, L
CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
 Ligand Interaction
CLF
Query on CLF

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Download CCD File 
A, D, J, K
FE(8)-S(7) CLUSTER
Fe8 S7
JKVMXLBGZBULKV-DHHOTQGYAO
 Ligand Interaction
HCA
Query on HCA

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Download CCD File 
A, C, I, K
3-HYDROXY-3-CARBOXY-ADIPIC ACID
C7 H10 O7
XKJVEVRQMLKSMO-SSDOTTSWSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.2 Å
  • R-Value Free: 0.329 
  • R-Value Work: 0.279 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 113.267α = 90.00
b = 214.937β = 90.00
c = 320.466γ = 90.00
Software Package:
Software NamePurpose
MOLREPphasing
SCALEPACKdata scaling
DENZOdata reduction
CNSrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2003-02-11
    Type: Initial release
  • Version 1.1: 2008-04-28
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance