Swg_01289 K00762 pyrE R01870Orotidine 5'-phosphate + Diphosphate <=> Orotate + 5-Phospho-alpha-D-ribose 1-diphosphate
orotidine-5'-phosphate:diphosphate phospho-alpha-D-ribosyl-transferase Swg_01290 K01591 pyrF R00965Orotidine 5'-phosphate <=> UMP + CO2
orotidine-5'-phosphate carboxy-lyase (UMP-forming)