Catalyzes the condensation of ATP and 5-phosphoribose 1-diphosphate to form N'-(5'-phosphoribosyl)-ATP (PR-ATP). Has a crucial role in the pathway because the rate of histidine biosynthesis seems to be controlled primarily by regulation of HisG enzymatic activity. 1-(5-phospho-beta-D-ribosyl)-ATP + diphosphate = 5-phospho-alpha-D-ribose 1-diphosphate + ATP Feedback inhibited by histidine. Amino-acid biosynthesis; L-histidine biosynthesis; L-histidine from 5-phospho-alpha-D-ribose 1-diphosphate: step 1/9. Equilibrium between an active dimeric form, an inactive hexameric form and higher aggregates. Interconversion between the various forms is largely reversible and is influenced by the natural substrates and inhibitors of the enzyme. Belongs to the ATP phosphoribosyltransferase family. Long subfamily.