The Effect of Amino Acid on the Uptake and Utilization of Tryptophan and other Precursors of Nicotinic Acid by Neurospora crassa

Abstract

SUMMARYThe influence of casein hydrolysate and certain amino acids on the uptake and utilization of tryptophan and other precursors of nicotinic acid biosynthesis by a mutant of Neurospora crmsa which can grow on tryptophan or nicotinic acid was investigated. Whereas casein hydrolysate and certain amino acids inhibited the growth of the organism when tryptophan, kynurenine, or 3-hydroxykynurenine was present in the medium, they had no effect in the presence of other precursors, i.e. 3-hydroxyanthranilic acid or nicotinic acid. Studies have been made with wild strain and the mutant on the amount of tryptophan taken up from the medium a t different periods of growth of the organism.

Effects of Amino Acids on the Utilization of Tryptophan and Indole for Growth by a Mutant of Neurospora crassa

“…The growth of another tyrosine-requiring mutant (T-145) on tyrosine was inhibited by 18 of 23 amino acids tested (DeBusk & 32 H. E. BROCKMAN Wagner, 1953). A mutant which grew on any one of the intermediates between indole and nicotinic acid was inhibited by 12 of 21 amino acids that were tested in combination with tryptophan, kynurenine or 3-hydroxykynurenine (Shanmugasundaram & Sarma, 1954; Panicker, Shanmugasundaram & Acharya, 1962). Soboren & Nyc (1961) reported that 4 of 17 naturally occurring amino acids inhibited growth of the tryptophan-requiring strain c-83.…”