Regulatory Role of Molecular Chaperones in Nitrogenase Biogenesis

Identification of an Fe protein Residue (Glu146) ofAzotobacter vinelandii Nitrogenase That Is Specifically Involved in FeMo Cofactor Insertion

“…Subsequently, several of these mutations were mapped to the nifH gene, and some were sequenced to identify their nifH genotype (28,(35)(36)(37)(38) (28). Site-directed mutagenesis was performed using the Mutagene mutagenesis kit, version 2, from Bio-Rad.…”

“…Homocitrate lactone was converted to the free acid as described elsewhere (50 (39) to try to locate conserved Fe protein residues that might be specifically involved only in one or both of the last two reactions. To do this we relied on information concerning the nifH genotypes of strains of K. pneumoniae or A. vinelandii that had been produced decades ago using chemical mutagenesis and that had Nif Ϫ phenotypes (35)(36)(37)(38). The idea was to look for residues that were not close to the [4Fe-4S] cluster or any of the regions of the Fe protein that were known to be important for MgATP binding, the MgATP-induced conformational change or for complex formation with the MoFe protein.…”