Figure 3.

Ala-AA, the proposed linear precursor of DPO, binds to and activates VqmA. A, structures of threonine, Ala-AA, and DPO (both tautomers). B, EMSA of VqmA binding to PvqmR DNA in the presence of threonine, DPO, water, or Ala-AA. Probe and protein concentrations were as in Fig. 1C. C, trypsin digestion of VqmA in the absence (H₂O, top) or presence of ligand (DPO, middle; Ala-AA, bottom). M, molecular weight marker; FL, full-length. Time points (min) are indicated above each lane. FL VqmA (∼27 kDa) and trypsin (∼23 kDa) are marked. Asterisks denote VqmA proteolytic cleavage products.