PpnN (pyrimidine/purine nucleotide 5'-monophosphate nucleosidase), widely conserved in gamma proteobacteria, plays a role in purine homeostasis. It can bind the the stringent response alarmones ppGpp and pppGpp and then, because of allosteric changes, have a much higher rate of cleavage of preferred substrate GMP. PpnN was previously known in E. coli as YgdH.
Jiyao W et al.(2023). "The conserved domain database in 2023.",