Regulation of Glutamate Dehydrogenases in Neurospora Crassa as a Response to Carbohydrates and Amino Acids in the Media

Abstract

Mycelial pads of N. crassa grown for 48 hr in minimal medium were harvested, washed, and transferred to test media containing a variety of carbon and nitrogen sources. When some amino acids served as the sole carbon source, NAD-GDH was induced and the activity of NADP-GDH declined. Addition of sucrose depressed or prevented induction of NAD-GDH while NADP·GDH activity was maintained. Internal amino acid concentrations increased when mycelial pads were incubated in amino acids that induced NAD-GDH, but these accumulated amino acids were only oxidized in the absence of sucrose. The rate of amino acid accumulation decreased if sucrose was present in the media.