Inhibition of decaprenylphosphoryl-β-d-ribose epimerization by BTZ. (A) Effect of different BTZ derivatives (table S1) on DPA production from DPR by using mycobacterial membranes in vitro. Lane 1, no drug control; lane 2, BTZ038; lane 3, BTZ043; lane 4, BTZ044; lane 5, BTZ045S; lane 6, BTZ045R. (B) Production of DPA from DPR requires both Rv3790 (DprE1) and Rv3791 (DprE2). E. coli strains that were used in the experiment (26) expressed the following M. tuberculosis proteins: lane 1, none; lane 2, Rv3790-Rv3791; lane 3, none; lane 4, Rv3791; lane 5, none; lane 6, Rv3790; lane 7, none; lane 8, Rv3790. (C) Effect of BTZ043 on DPA production by using cell wall fractions from BTZ-sensitive M. bovis BCG and its BTZ-resistant mutant, BN2 (Table 1).