The assembly of R. capsulatus XDH involves the synthesis of the XdhA and XdhB subunits, the dimerization of both subunits, the insertion of FeSI, FeSII and FAD into the XdhA subunit, dimerization of two (αβ) dimers via the XdhB subunit to form the Moco-free apo-XDH, and finally, insertion of sulfurated Moco into of XdhC. XdhC binds Mo-MPT and the equatorial Mo=S is inserted into Moco before its incorporation into XDH by the sulfurtransferase function of the NifS4 protein. After the formation of sulfurated Mo-MPT, XdhC interacts with XDH for final Moco insertion.