IDENTIFICATION OF GENE-PRODUCTS FROM THE AZOTOBACTER-VINELANDI NIFBFDXNNIFOQ OPERON

The Azotobacter vinelandii nifBfdxNnifOQ operon is required for synthe sis of the nitrogenase iron-molybdenum cofactor. To further characteri ze the roles of its gene products, specific antibodies against NifB an d NifO were generated, and the NifB, NifO and NifQ gene products were visualized and identified in nitrogen-fixing A. vinelandii cell extrac ts by a combination of two-dimensional gel electrophoresis of radiolab elled extracts and immunological detection methods, The three proteins showed apparent pI and M-r values similar to those expected from sequ ence data, except for NifO, which showed an apparent M-r of ca. 23 kDa (vs. 16 kDa expected).