Nucleotide-iron-sulfur cluster signal transduction in the nitrogenase iron-protein: the role of Asp125.
Electron transfer in nitrogenase involves a gating process initiated by MgATP (magnesium adenosine triphosphate) binding to Fe-protein. The redox site, an 4Fe:4S cluster, is structurally separated from the MgATP binding site. For MgATP hydrolysis to be coupled to electron transfer, a signal transduction mechanism is proposed that is similar to that in guanosine triphosphatase proteins. Based on the three-dimensional structure of Fe-protein, Asp125 is likely to be part of a putative transduction path. Altered Fe-protein with Glu replacing Asp has been prepared and retains the ability for the initial nucleotide-dependent conformational change. However, either MgADP or MgATP can induce the shift and Mg binding to the nucleotide is no longer essential.
Wolle
D
D
Department of Biochemistry, University of Minnesota, Minneapolis 55455.
Dean
D R
DR
Howard
J B
JB
D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism*; D001224:Aspartic Acid / Q000378:metabolism*; D016948:Azotobacter vinelandii / Q000201:enzymology; D001665:Binding Sites; D003460:Crystallization; D004579:Electron Transport; D005971:Glutamates; D018698:Glutamic Acid; D007506:Iron-Sulfur Proteins / Q000378:metabolism*; D015394:Molecular Structure; D016297:Mutagenesis, Site-Directed; D009591:Nitrogenase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011487:Protein Conformation; D015398:Signal Transduction / Q000502:physiology*
D005971:Glutamates; D007506:Iron-Sulfur Proteins; D001224:Aspartic Acid; D018698:Glutamic Acid; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D009591:Nitrogenase