4.1.99.22	malfunction	cyclic pyranopterin monophosphate (cPMP) is strongly decreased in cnx2 mutants. Phenotype of T-DNA insertion mutant line cnx2-1, the cnx2-1 knockout is seedling-lethal but growth is rescued by ammonia, overview. Mutant xd22 has a mutation in CNX2 affecting the proximal FeS cluster loop. With hypoxanthine as a substrate, no activity is detectable in leaves from cnx2-2 plants. Nitrate reductase activity in leaf extract from cnx2-2 is 55% compared to wild-type values. Genetic complementation and strongly decreased activities of Moco enzymes show that the mutation in xd22 (R88Q) is located in CNX2, line cnx2-2, encoding the first step in Moco biosynthesis. The cnx2-2 mutation is not a knockout allele and growth is rescued by ammonia. Crosses between heterozygous cnx2-1 CNX2 and homozygous cnx2-2 plants give F1 offspring in two phenotype categories: seedlings with wild-type appearance corresponding to cnx2-1 CNX2 and small chlorotic seedlings that are genotyped as cnx2-1 cnx2-2	-, 747034	
4.1.99.22	metabolism	molybdenum cofactor (Moco) biosynthesis starts with the condensation of GTP into cyclic pyranopterin monophosphate (cPMP) by the consecutive action of GTP 3',8-cyclase and cPMP synthase, encoded by CNX2 and CNX3 in plants, respectively, pathways for FeS cluster assembly and Moco biosynthesis in Arabidopsis thaliana, overview	-, 747034	
4.1.99.22	metabolism	the enzyme MoaA catalyzes the fist step of molybdenum cofactor (Moco) biosynthesis	-, 747120	
4.1.99.22	physiological function	the GG motif is essential for the activity of MoaA to produce (8S)-3',8-cyclo-7,8-dihydroguanosine 5'-triphosphate from GTP, and synthetic peptides corresponding to the C-terminal region of wild-type MoaA rescue the GTP 3',8-cyclase activity of the GG-motif mutants. The C-terminal tail containing the GG motif interacts with the SAM-binding pocket of MoaA, and is essential for the binding of SAM and subsequent radical initiation	-, 738455	
4.1.99.22	physiological function	the MoaA protein is involved in the conversion of 5'-GTP to cyclic pyranopterin monophosphate in the fist step of molybdenum cofactor (Moco) biosynthesis	-, 747120	
4.1.99.22	physiological function	the physiological function of MoaA is the conversion of GTP to (8S)-3',8-cyclo-7,8-dihydroguanosine 5'-triphosphate (GTP 3?,8-cyclase), and that of MoaC is to catalyze the rearrangement of (8S)-3',8-cyclo-7,8-dihydroguanosine 5'-triphosphate into cyclic pyranopterin	-, 739551