PURIFICATION OF THE AZOTOBACTER-VINELANDII NIFV-ENCODED HOMOCITRATE SYNTHASE

The nifV gene product (NifV) from Azotobacter vinelandii was recombina ntly expressed at high levels in Escherichia coli and purified. NifV i s a homodimer that catalyzes the condensation of acetyl coenzyme A (ac etyl-CoA) and alpha-ketoglutarate. Although alpha-ketoglutarate suppor ts the highest level of activity, NifV will also catalyze the condensa tion of acetyl-CoA and certain other keto acids. E. coli cells in whic h a high level of nifV expression is induced excrete homocitrate into the growth medium.