Fig. 4.

(A) Specificity of L-tryptophan requirement as a function of species-specific systems-level pathway structure. (B) Multiple simultaneous specific auxotrophies as a result of single gene deletion. (C) Auxotrophies as a result of deletion of multiple isozymes. In K. pneumoniae str. KP11, argI and argF are both absent. (D) Pseudospecific auxotrophies in which the alternative to one nutrient requirement (e.g., shikimate) is the simultaneous requirement for multiple nutrients (e.g., L-phenylalanine, L-tryptophan, and L-tyrosine).