InterPro domain: IPR004733

The purine biosynthetic pathway in prokaryotes enlists eleven enzymes, six of which use ATP. Enzymes 5 and 6 of this pathway, formylglycinamide ribonucleotide (FGAR) amidotransferase (PurL) and aminoimidazole ribonucleotide (AIR) synthetase (PurM or AIRS) utilise ATP to activate the oxygen of an amide within their substrate toward nucleophilic attack by a nitrogen. PurM (also known as phosphoribosyl-aminoimidazole synthetase or phosphoribosylformylglycinamidine cyclo-ligase) uses the product of PurL, formylglycinamidine ribonucleotide (FGAM) and ATP to make AIR, ADP and P(i) [ 1 , 2 ]. The N-terminal domain of PurM is related to the ATP-binding domains of hydrogen expression/formation protein HypE, the AIR synthases, selenophosphate synthetase (SelD), and FGAM synthase and is thought to bind ATP [ 3 ].

1. Nucleotide sequence of the purM gene encoding 5'-phosphoribosyl-5-aminoimidazole synthetase of Escherichia coli K12. J. Biol. Chem. 261, 10632-6
2. X-ray crystal structure of aminoimidazole ribonucleotide synthetase (PurM), from the Escherichia coli purine biosynthetic pathway at 2.5 A resolution. Structure 7, 1155-66
3. Investigation of the ATP binding site of Escherichia coli aminoimidazole ribonucleotide synthetase using affinity labeling and site-directed mutagenesis. Biochemistry 38, 9831-9