Pyrophosphate can serve as a source of phosphoryl groups for the phosphorylation of E. coli proteins. The main target of such phosphorylation is a 49-kDa protein which is covalently modified at serine. The same phosphorylation pattern is obtained in the presence of ATP, which suggests that pyrophosphate can substitute for ATP for bacterial protein phosphorylation.
Duclos, B., Vaganay, E., Dadssi, M., & Cozzone, A. J. (1996). Pyrophosphate is a source of phosphoryl groups for Escherichia coli protein phosphorylation. FEMS Microbiology Letters, 145(1), 49–54. https://doi.org/10.1016/0378-1097(96)00384-9