Azotobacter vinelandii nifD- and nifE -encoded polypeptides share structural homology

The Azotobacter vinelandii nifE gene was isolated and its complete nucleotide sequence was determined. The amino acid sequences deduced from the A. vinelandii nifE and nifD gene sequences were compared and found to share striking primary sequence homology. This homology implies a functional and possibly an evolutionary relationship between these two gene products. The structural homology is discussed with regard to the potential FeMo cofactor binding properties of these polypeptides and the possible role of a nifEN product complex as a surrogate MoFe protein.