Crystal structure of the nitrogenase iron protein from Azotobacter vinelandii

摘要: The nitrogenase enzyme system consists of two component proteins, an iron (Fe-) protein and a molybdenum-iron (MoFe)-protein. Prior to substrate reduction, electrons are transferred from Fe-protein MoFe-protein in ATP-dependent process. coupling ATP hydrolysis electron transfer is mediated by Fe-protein, which the only known reductant supporting catalytic activity (8). dimer identical 32kDa subunits, sequences highly conserved both conventional alternate nitrogenases diverse group prokaryotes. symmetrically binds one 4Fe-4S cluster Cys 97 132 each subunit (sequence numbering Azotobacter vinelandii Fe-protein) (2,4). Unusual aspects include ATP-electron unique environment, unlike any observed ferredoxin structures. To address structural basis these properties, we have determined crystal structure A. at 3.0A resolution. At present, 247 289 residues been modeled as poly-alanine chain, detailed fitting actual side chains progress. current model sufficient begin addressing questions concerning overall shape fold protein, environment cluster, probable nucleotide binding site, site(s) interaction with MoFe-protein, interactions interface.