Sydney Brenner isolated Salmonella typhimurium mutants that

Sydney Brenner isolated Salmonella typhimurium mutants that were implicated in the biosynthesis of tryptophan and would not grow on minimal medium. When these mutants were tested on minimal medium to which one of four compounds (indol glycerol phosphate, indole, anthranilic acid, and tryptophan) had been added, the growth responses shown in the following table were obtained. Which of the following choices gives the CORRECT ordering of the four molecules in a biochemical pathway leading to the synthesis of tryptophan?

Solution

The correct order of compounds in tryptophan biosynthesis is Anthranilic acid > indole glycerol phosphate > Indole > Tryptophan. Trp-8 mutant is able to synthesize all compounds and consists of all necessary enzymes in the biosynthetic pathway of tryptophan. Option 1 is correct.