Catalyzes the first committed step of 'de novo' purine biosynthesis from glutamine. Involved in plastid biogenesis and cell division. 5-phospho-beta-D-ribosylamine + diphosphate + L-glutamate = 5-phospho-alpha-D-ribose 1-diphosphate + H2O + L-glutamine Binds 1 [4Fe-4S] cluster per subunit. Binds 1 Mg(2+) ion per subunit. Purine metabolism; IMP biosynthesis via de novo pathway; N(1)-(5-phospho-D-ribosyl)glycinamide from 5-phospho-alpha-D-ribose 1-diphosphate: step 1/2. Expressed in flowers and roots. Also present in leaves, and, to a lower extent, in cotyledons. In the C-terminal section; belongs to the purine/pyrimidine phosphoribosyltransferase family.