Molybdenum cofactor synthesis C-terminal (IPR010505)

Short name: Mob_synth_C

Domain relationships



The majority of molybdenum-containing enzymes utilise a molybdenum cofactor (MoCF or Moco) consisting of a Mo atom coordinated via a cis-dithiolene moiety to molybdopterin (MPT). MoCF is ubiquitous in nature, and the pathway for MoCF biosynthesis is conserved in all three domains of life. MoCF-containing enzymes function as oxidoreductases in carbon, nitrogen, and sulphur metabolism [PMID: 16784786, PMID: 12114025].

In Escherichia coli, biosynthesis of MoCF is a three stage process. It begins with the MoaA and MoaC conversion of GTP to the meta-stable pterin intermediate precursor Z. The second stage involves MPT synthase (MoaD and MoaE), which converts precursor Z to MPT; MoeB is involved in the recycling of MPT synthase. The final step in MoCF synthesis is the attachment of mononuclear Mo to MPT, a process that requires MoeA and which is enhanced by MogA in an Mg2 ATP-dependent manner [PMID: 17198377]. MoCF is the active co-factor in eukaryotic and some prokaryotic molybdo-enzymes, but the majority of bacterial enzymes requiring MoCF, need a modification of MTP for it to be active; MobA is involved in the attachment of a nucleotide monophosphate to MPT resulting in the MGD co-factor, the active co-factor for most prokaryotic molybdo-enzymes. Bacterial two-hybrid studies have revealed the close interactions between MoeA, MogA, and MobA in the synthesis of MoCF [PMID: 12372836]. Moreover the close functional association of MoeA and MogA in the synthesis of MoCF is supported by fact that the known eukaryotic homologues to MoeA and MogA exist as fusion proteins: CNX1 (Q39054) of Arabidopsis thaliana (Mouse-ear cress), mammalian Gephryin (e.g. Q9NQX3) and Drosophila melanogaster (Fruit fly) Cinnamon (P39205) [PMID: 8528286].

This entry represents MoaA (also known as GTP 3',8-cyclase), which belongs to a family of enzymes involved in the synthesis of metallo-cofactors (IPR000385). Each subunit of the MoaA dimer is comprised of an N-terminal SAM domain (IPR007197) that contains the [4Fe-4S] cluster typical for this family of enzymes, as well as an additional [4Fe-4S] cluster in the C-terminal domain that is unique to MoaA proteins [PMID: 15317939]. The unique Fe site of the C-terminal [4Fe-4S] cluster is thought to be involved in the binding and activation of 5'-GTP.

Mutations in the human MoCF biosynthesis proteins MOCS1, MOCS2 or GEPH cause MoCF Deficiency type A (MOCOD), causing the loss of activity of MoCF-containing enzymes, resulting in neurological abnormalities and death [PMID: 12754701].

GO terms

Biological Process

GO:0006777 Mo-molybdopterin cofactor biosynthetic process

Molecular Function

GO:0051539 4 iron, 4 sulfur cluster binding

Cellular Component

GO:0019008 molybdopterin synthase complex

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.