(1S,2R)-1-C-(indol-3-yl)glycerol 3-phosphate + L-serine = D-glyceraldehyde 3-phosphate + H2O + L-tryptophan Amino-acid biosynthesis; L-tryptophan biosynthesis; L-tryptophan from chorismate: step 5/5. Present with 15500 molecules/cell in log phase SD medium. In the N-terminal section; belongs to the TrpA family. In the C-terminal section; belongs to the TrpB family.