FIG. 1.

Amounts of NifL and NifA in wild-type (wt) and glnK mutant strains of E. coli. Amounts of proteins in crude cell extracts were determined by Western blotting with polyclonal antisera against NifL (lanes 1 to 4) or NifA (lanes 5 to 8). All strains carried plasmid pNH3 (Ptac-nifLA). Cultures were grown in K medium under derepressing conditions, and expression of NifL and NifA was induced with 10 μM IPTG (+) or was not induced (−). Lanes: 1, 2, 5, and 6, strain NCM1528 (wild type); 3, 4, 7, and 8, strain NCM1974 (glnK mutant).