Uses inorganic polyphosphate (polyP) as a donor to convert ADP to ATP. Can also convert GDP to GTP, with lower efficiency. Cannot dephosphorylate ATP in the presence of polyP. [phosphate](n) + ATP = [phosphate](n+1) + ADP [phosphate](n) + GTP = [phosphate](n+1) + GDP Has low activity with Co(2+) or Ni(2+). kcat is 8.6 sec(-1) with polyP as substrate. kcat is 7.6 sec(-1) with ADP as substrate. kcat is 0.8 sec(-1) with GDP as substrate. Optimum pH is 8.0-9.5. Homotetramer. Belongs to the polyphosphate kinase 2 (PPK2) family. Class I subfamily.