Bifunctional enzyme that catalyzes two steps during fosfomycin biosynthesis (PubMed:28727444). It catalyzes the conversion of phosphoenolpyruvate (PEP) to phosphonopyruvate (PnPy), the first step of the pathway. It also catalyzes the cytidylylation of the 2-hydroxyethylphosphonate (HEP) intermediate to produce cytidylyl-2-hydroxyethylphosphonate (HEP-CMP), the fourth step of the pathway (PubMed:28727444). 2-hydroxyethylphosphonate + CTP = cytidine 5'-{[hydroxy(2-hydroxyethyl)phosphonoyl]phosphate} + diphosphate H(+) + phosphoenolpyruvate = 3-phosphonopyruvate The CyTase reaction requires a divalent metal ion. Highest activity is observed with Co(2+), but it can also use Mg2(+), Ni2(+), Fe2(+) or Mn2(+). Antibiotic biosynthesis; fosfomycin biosynthesis. Contains an N-terminal cytidylyltransferase (CyTase) domain and a C-terminal phosphoenolpyruvate phosphomutase domain. Deletion mutant does not produce fosfomycin. In the N-terminal section; belongs to the cytidylyltransferase family. In the C-terminal section; belongs to the isocitrate lyase/PEP mutase superfamily. PEP mutase family.