InterPro domain: IPR036921

This entry represents a structural domain superfamily with a core structure consisting of beta-alpha-beta-alpha-beta(2), which is found in two enzymes of the purine biosynthetic pathway: at the N-terminal of phosphoribosylformylglycinamidine cyclo-ligase (also known as aminoimidazole ribonucleotide (AIR) synthetase, PurM) [ 1 ], as well as the N1 and N2 domains of phosphoribosylformylglycinamidine synthase subunit PurL (also known as formylglycinamide ribonucleotide (FGAR) amidotransferase) (PurM-like module) [ 2 ]. PurM and PurL utilise ATP to activate the oxygen of an amide within their substrate toward nucleophilic attack by a nitrogen. PurM uses the product of PurL, formylglycinamidine ribonucleotide (FGAM) and ATP to make AIR, ADP and P(i). It is also found as domains 1 and 3 in phosphoribosylformylglycinamidine synthase II (smPurL) ( 6.3.5.3 ) (carries a duplication: tandem repeats of two PurM-like units arranged like the PurM subunits in the dimer) [ 3 ].

This domain is also found at the N-terminal of thiamine monophosphate kinase ( 2.7.4.16 ) (ThiL) [ 4 ]. ThiL phosphorylates thiamin monophosphate to form thiamin pyrophosphate, an essential cofactor that is synthesised de novo by Salmonella typhimurium.

1. 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
2. Domain organization of Salmonella typhimurium formylglycinamide ribonucleotide amidotransferase revealed by X-ray crystallography. Biochemistry 43, 10328-42
3. Crystal structure of phosphoribosylformylglycinamidine synthase II (smPurL) from Thermotoga maritima at 2.15 A resolution. Proteins 63, 1106-11
4. Characterization of thiL, encoding thiamin-monophosphate kinase, in Salmonella typhimurium. J. Biol. Chem. 272, 15702-7