Ppx/GppA phosphatases belong to ASKHA (acetate and sugar kinases, Hsp70, actin) which has an N-terminal (Pfam:PF02541) nucleotide-binding domain (domains I/II), domain III which corresponds to the catalytic phosphohydrolase domain with the common helical fold and domain IV [1-3]. This entry represents domain III.

1: Origin of exopolyphosphatase processivity: Fusion of an ASKHA phosphotransferase and a cyclic nucleotide phosphodiesterase homolog. Alvarado J, Ghosh A, Janovitz T, Jauregui A, Hasson MS, Sanders DA; Structure. 2006;14:1263-1272. PMID:16905100

2: The structure of the exopolyphosphatase (PPX) from Escherichia coli O157:H7 suggests a binding mode for long polyphosphate chains. Rangarajan ES, Nadeau G, Li Y, Wagner J, Hung MN, Schrag JD, Cygler M, Matte A; J Mol Biol. 2006;359:1249-1260. PMID:16678853

3: Structure and activity of PPX/GppA homologs from Escherichia coli and Helicobacter pylori. Song H, Dharmasena MN, Wang C, Shaw GX, Cherry S, Tropea JE, Jin DJ, Ji X; FEBS J. 2020;287:1865-1885. PMID:31679177