Inhibition by D-Glutamate of Growth and Glutamate Dehydrogenase Activity of Neurospora crassa

Abstract

d-Glutamic acid (d-glu) inhibited strongly the growth of two strains of Neurospora crassa in a minimal medium. The inhibition was completely annulled by equivalent concentrations of l-glutamic acid (l-glu) or l-gluta-mine. d-G1u also inhibited glutamate dehydrogenase (GDH) and was only antagonized completely by 10 equivalents of l-glu. d-G1u in media containing l-glu increased GDH-activity, presumably by de-repression. d-G1u showed no effect on glutamine synthetase and γ-glutamyl transferase activities. Inhibition of growth of N. crassa by d-glu thus seems due to the interference with glutamate synthesis by inhibition of GDH-activity.