Abstract
SUMMARY: A total of 41 mutants lacking NADP L-glutamate dehydrogenase (NADP-GDH) activity have been studied. All the mutations were located at the gdhA locus within 0.1% recombination of gdhA1. Two mutants, gdhA1 and gdhA2, out of five examined, produced cross-reacting material which neutralized NADP-GDH antiserum. The mutant gdhA9 has altered Km values for all five substrates: ammonium, α-ketoglutarate, L-glutamate, NADPH and NADP. The mutant gdhA20 had temperature-sensitive growth, abnormal ammonium-regulation characteristics and thermolabile NADP-GDH activity. These results show that gdhA is the structural gene for NADP-GDH.