InterPro domain: IPR001453

MoaB/Mog domain, also known as Cnx1G domain, is found in the bacterial molybdenum cofactor (Moco) biosynthesis protein MoaB/Mog and N-terminal of the eukaryotic MoCF biosynthesis proteins, such as the Drosophila protein cinnamon, the Arabidopsis protein cnx1 and the mammal protein gephyrin [ 1 ]. These proteins are involved in the final steps of Moco synthesis. In E. coli two proteins, MogA and MoeA are essential for Mo insertion into molybdopterin, while in plants and animals one fusion protein with two domains (G and E domains) fulfils this function. The G domain of Cnx1 and gephyrin shares similarity with MoaB/Mog, while their E domain displays similarities to the sulfurtransferase rhodanese (homologous to E. coli MoeA/chlE) [ 2 ]. Structurally, MogA is folded into a compact molecule with alpha/beta/alpha architecture and forms a trimer [ 3 ]. The Cnx1G domain has been shown to bind molybdopterin [ 4 ].

This domain is also found in N-terminal of the FAD synthases belonging to the COG1058 family that catalyses the adenylation of flavin mononucleotide (FMN) to form flavin adenine dinucleotide (FAD) coenzyme [ 5 ]. The COG1058 family member CinA from Thermus thermophilus is shown to have both nicotinamide mononucleotide deamidase and ADP-ribose pyrophosphatase activities, with ADP-ribose pyrophosphatase activity attributed to the N-termminal domain [ 6 ].

1. Molybdenum cofactors, enzymes and pathways. Nature 460, 839-47
2. Evidence for the physiological role of a rhodanese-like protein for the biosynthesis of the molybdenum cofactor in humans. Proc. Natl. Acad. Sci. U.S.A. 101, 5946-51
3. Crystal structure of the gephyrin-related molybdenum cofactor biosynthesis protein MogA from Escherichia coli. J. Biol. Chem. 275, 1814-22
4. The active site of the molybdenum cofactor biosynthetic protein domain Cnx1G. Arch. Biochem. Biophys. 411, 36-46
5. Genomics-guided analysis of NAD recycling yields functional elucidation of COG1058 as a new family of pyrophosphatases. PLoS ONE 8, e65595
6. Structure and Mechanism of the Bifunctional CinA Enzyme from Thermus thermophilus. J. Biol. Chem. 289, 33187-97