The nitrogenase FeMo-cofactor and P-cluster pair: 2.2 A resolution structures.

Structures recently proposed for the FeMo-cofactor and P-cluster pair of the nitrogenase molybdenum-iron (MoFe)-protein from Azotobacter vinelandii have been crystallographically verified at 2.2 angstrom resolution. Significantly, no hexacoordinate sulfur atoms are observed in either type of metal center. Consequently, the six bridged iron atoms in the FeMo-cofactor are trigonally coordinated by nonprotein ligands, although there may be some iron-iron bonding interactions that could provide a fourth coordination interaction for these sites. Two of the cluster sulfurs in the P-cluster pair are very close together (approximately 2.1 angstroms), indicating that they form a disulfide bond. These findings indicate that a cavity exists in the interior of the FeMo-cofactor that could be involved in substrate binding and suggest that redox reactions at the P-cluster pair may be linked to transitions of two cluster-bound sulfurs between disulfide and sulfide oxidation states.

[1]  D. C. Rees,et al.  Crystallographic structure and functional implications of the nitrogenase molybdenum–iron protein from Azotobacter vinelandii , 1992, Nature.

[2]  D C Rees,et al.  Structural models for the metal centers in the nitrogenase molybdenum-iron protein. , 1992, Science.

[3]  A. Moffat.  An intimate look at nitrogen's bio-partner. , 1992, Science.

[4]  W. Orme-Johnson,et al.  Nitrogenase structure: where to now? , 1992, Science.

[5]  R. Eady,et al.  Metalloclusters of the nitrogenases. , 1992, European journal of biochemistry.

[6]  J. Smits,et al.  Synthesis and characterization of the iron-sulfur cluster compounds [Fe4S5(MeCp)4](PF6)y (y = 0-2). X-ray structure determination of [Fe4S5(MeCp)4](PF6) , 1992 .

[7]  D. Sellmann,et al.  Nitrogenase Model Compounds: [μ‐N2H2{Fe(“NHS4”)}2], the Prototype for the Coordination of Diazene to Iron Sulfur Centers and Its Stabilization through Strong NH ⃛ S Hydrogen Bonds , 1989 .

[8]  A. Brunger.  Crystallographic refinement by simulated annealing , 1988 .

[9]  Brian W. Matthews,et al.  An efficient general-purpose least-squares refinement program for macromolecular structures , 1987 .

[10]  E. Sinn,et al.  Sulfur-bridged dimers obtained from μ-dithiobis(tricarbonyliron) , 1985 .

[11]  G. Geoffroy,et al.  Formyl, acyl, and carbene derivatives of Fe3(.mu.3-EPh)2(CO)9 (E = nitrogen or phosphorus). Unique examples of carbene-nitrene and carbene-phosphinidene coupling , 1985 .

[12]  W. Orme-Johnson.  Molecular basis of biological nitrogen fixation. , 1985, Annual review of biophysics and biophysical chemistry.

[13]  E. Sinn,et al.  Synthesis and x-ray structure of the [Fe4S4(CO)12]2- ion: an example of intermolecular disulfide formation by the (.mu.-S)2Fe2(CO)6 unit , 1984 .

[14]  C. Chu,et al.  Synthesis, structure, and bonding of the [Fe4(NO)4(.mu.3-S)2(.mu.3-NCMe3)2]n series (n = 0,-1) containing a cubane-like Fe4S2N2 core: stereochemical influence due to one-electron reduction of a completely bonding tetrahedral metal system , 1982 .

[15]  F. Cotton,et al.  Additions and Corrections - A New Mode of Carbonyl Scrambling, Structure and Dynamics of (1,2-Diazine)heptacarbonyldiiron(Fe-Fe) , 1977 .