1-(5-phospho-beta-D-ribosyl)-ATP + H2O = 1-(5-phospho-beta-D-ribosyl)-5'-AMP + diphosphate + H(+) Amino-acid biosynthesis; L-histidine biosynthesis; L-histidine from 5-phospho-alpha-D-ribose 1-diphosphate: step 2/9. Belongs to the PRA-PH family.