SirA, YedF, and YeeD. Two-layered alpha/beta sandwich domain. SirA (also known as UvrY, and YhhP) belongs to a family of bacterial two-component response regulators that controls secondary metabolism and virulence. The other member of this two-component system is a sensor kinase called BarA which phosphorylates SirA. A variety of microorganisms have similar proteins, all of which contain a common CPxP sequence motif in the N-terminal region. YhhP is suggested to be important for normal cell division and growth in rich nutrient medium. Moreover, despite a low primary sequence similarity, the YccP structure closely resembles the non-homologous C-terminal RNA-binding domain of E. coli translation initiation factor IF3. The signature CPxP motif serves to stabilize the N-terminal helix as part of the N-capping box and might be important in mRNA-binding.
Jiyao W et al.(2023). "The conserved domain database in 2023.",