Iron-sulfur cluster assembly: NifU-directed activation of the nitrogenase Fe protein.
The NifU protein is a homodimer that is proposed to provide a molecular scaffold for the assembly of [Fe-S] clusters uniquely destined for the maturation of the nitrogenase catalytic components. There are three domains contained within NifU, with the N-terminal domain exhibiting a high degree of primary sequence similarity to a related family of [Fe-S] cluster biosynthetic scaffolds designated IscU. The C-terminal domain of NifU exhibits sequence similarity to a second family of proposed [Fe-S] cluster biosynthetic scaffolds designated Nfu. Genetic experiments described here involving amino acid substitutions within the N-terminal and C-terminal domains of NifU indicate that both domains can separately participate in nitrogenase-specific [Fe-S] cluster formation, although the N-terminal domain appears to have the dominant function. These in vivo experiments were supported by in vitro [Fe-S] cluster assembly and transfer experiments involving the activation of an apo-form of the nitrogenase Fe protein.
Department of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, USA.
Patricia C
PC
Dos Santos
Archer D
AD
Smith
Jeverson
J
Frazzon
Valerie L
VL
Cash
Michael K
MK
Johnson
Dennis R
DR
Dean
D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D020134:Catalytic Domain; D003545:Cysteine / Q000737:chemistry; D019281:Dimerization; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D005838:Genotype; D005810:Multigene Family; D009154:Mutation; D010088:Oxidoreductases / Q000737:chemistry*; D010957:Plasmids / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism*
D001426:Bacterial Proteins; C088637:NifU protein, Bacteria; D011994:Recombinant Proteins; D014157:Transcription Factors; C080001:nifS protein, Bacteria; D010088:Oxidoreductases; C029130:nitrogenase reductase; D003545:Cysteine