The chaperone FdsC for Rhodobacter capsulatus formate dehydrogenase binds the bis-molybdopterin guanine dinucleotide cofactor

• The Moco insertion into R. capsulatus FDH depends on the specific chaperone FdsC.
• FdsC was purified from E. coli with bound bis-MGD.
• The bis-MGD on FdsC can be used as Moco source to reconstitute TorA activity.
• FdsC interacts with FdsD, MobA and TorA for bis-MGD insertion.
• This is the first evidence for bis-MGD binding to a chaperone.

Molybdoenzymes are complex enzymes in which the molybdenum cofactor (Moco) is deeply buried in the enzyme. Most molybdoenzymes contain a specific chaperone for the insertion of Moco. For the formate dehydrogenase FdsGBA from Rhodobacter capsulatus the two chaperones FdsC and FdsD were identified to be essential for enzyme activity, but are not a subunit of the mature enzyme. Here, we purified and characterized the FdsC protein after heterologous expression in Escherichia coli. We were able to copurify FdsC with the bound Moco derivate bis-molybdopterin guanine dinucleotide. This cofactor successfully was used as a source to reconstitute the activity of molybdoenzymes.

Structured summary of protein interactionsFdsC and FdsCbind by molecular sieving (View interaction)FdsDbinds to RcMobA by surface plasmon resonance (View interaction)FdsCbinds to RcMobA by surface plasmon resonance (View interaction)FdsCbinds to FdsA by surface plasmon resonance (View interaction)