The α-subunit (TrpA) of the allosterically regulated bifunctional tryptophan synthase αββα enzyme catalyzes the retro-aldol cleavage of indole-glycerol phosphate (IGP) to d-glyceraldehyde 3-phosphate (G3P) and indole. The activity of the enzyme is highly dependent on the β-subunit (TrpB), which allosterically regulates and activates TrpA for enhanced function. This contrasts with the homologous BX1 enzyme from <i>Zea mays</i> that can catalyze the same reaction as TrpA without requiring the presence of any additio…