FIG 3.

PpnN from S. Typhimurium strain SL1344 is a pyrimidine/purine nucleosidase. (A and B) PpnN hydrolyzes uridine 5′-monophosphate (UMP) to uracil and ribose 5′-phosphate. Introduction of an E264Q catalytic site mutation in PpnN abrogates protein function. Data are representative of two replicates.