Bacteria tryptophan pathway, gene-enzyme

Fio. 3. Gene-enzyme relationships in the tryptophan pathway of bacteria. The gene designated by a question mark represents a possible location (inferred from mapping distances) of the gene coding for the smaller protein component of AS in P. putida. The gene has not yet been identified by a specific mutational defect. Dashed lines represent relationships whose existence are still in question. See the text for further explanations. 

Ordering of Biosynthetic Pathways A simple example of the first type of process Is the biosynthesis of a metabolite such as the amino acid tryptophan In bacteria. In this case, each of the enzymes required for synthesis of tryptophan catalyzes the conversion of one of the intermediates in the pathway to the next. In E. coli, the genes encoding these enzymes lie adjacent to one another in the genome, constituting the... 

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