FIGURE 8.

Model for the biosynthesis of MPT in E. coli. The sulfur transfer pathway for the formation of the thiocarboxylate group on MoaD involves two sulfurtransferase proteins, IscS and YnjE, and l-cysteine as sulfur source. Prior to the sulfuration, MoaD is adenylated by MoeB. After sulfur transfer, thiocarboxylated MoaD dissociates from MoeB and reassociates with MoaE, forming active MPT synthase, which in turn converts cPMP to MPT. We believe that the proteins form a transient complex in the cell.