The Biosynthesis of the Molybdenum Cofactor in Escherichia coli and Its Connection to FeS Cluster Assembly and the Thiolation of tRNA

Figure 7

Model for the role of FdsC in bis-MGD insertion into R. capsulatus FDH. Shown is a scheme for bis-MGD biosynthesis from two Mo-MPT molecules via a bis-Mo-MPT intermediate. MobA binds Mo-MPT and catalyzes first the synthesis of bis-Mo-MPT and then the synthesis of bis-MGD by ligation of two GMP molecules to each MPT moiety in bis-Mo-MPT. Further, bis-MGD is transferred from MobA to FdsC. FdsC, FdsD, and MobA were shown to form a complex and are believed to protect the bis-MGD cofactor from oxidation before its insertion into the FdsA subunit of R. capsulatus FDH. Additionally, FdsC is believed to contribute to the specificity for bis-MGD insertion into FDH. The role of FdsD in the reaction is not completely resolved so far.