InterPro domain: IPR018946

Alkaline phosphatase D (PhoD) [ 1 ] catalyses the reaction: phosphate monoester + H(2)O = an alcohol + phosphate. PhoD is similar to Ca(2+)-dependent phospholipase D [ 2 ], which catalyses the hydrolysis of the ester bond between the phosphatidic acid and alcohol moieties of phospholipids [ 3 , 4 ].

PhoD (also known as alkaline phosphatase D/APaseD in Bacillus subtilis) is a secreted phosphodiesterase encoded by phoD of the Pho regulon in Bacillus subtilis. PhoD homologs are found in prokaryotes, eukaryotes, and archaea. PhoD contains a twin arginine (RR) motif and is transported by the Tat (Twin-arginine translocation) translocation pathway machinery (TatAyCy) [ 5 , 5 , 6 , 7 ]. Proteins containing this domain also includes the Fusarium oxysporum Fso1 protein [ 8 ].

PhoD belongs to the metallophosphatase (MPP) superfamily. MPPs are functionally diverse, but all share a conserved domain with an active site consisting of two metal ions (usually manganese, iron, or zinc) coordinated with octahedral geometry by a cage of histidine, aspartate, and asparagine residues. The MPP superfamily includes: Mre11/SbcD-like exonucleases, Dbr1-like RNA lariat debranching enzymes, YfcE-like phosphodiesterases, purple acid phosphatases (PAPs), YbbF-like UDP-2,3-diacylglucosamine hydrolases, and acid sphingomyelinases (ASMases). The conserved domain is a double beta-sheet sandwich with a di-metal active site made up of residues located at the C-terminal side of the sheets. This domain is thought to allow for productive metal coordination [ 9 ].

1. A Bacillus subtilis secreted phosphodiesterase/alkaline phosphatase is the product of a Pho regulon gene, phoD. Microbiology (Reading, Engl.) 142 ( Pt 8), 2041-7
2. Phosphate control of phoA, phoC and phoD gene expression in Streptomyces coelicolor reveals significant differences in binding of PhoP to their promoter regions. Microbiology (Reading, Engl.) 153, 3527-37
3. Expression and characterization of a heterodimer of Streptomyces chromofuscus phospholipase D. Biochim. Biophys. Acta 1703, 43-51
4. An iron-dependent bacterial phospholipase D reminiscent of purple acid phosphatases. J. Biol. Chem. 278, 13706-11
5. Overflow of a hyper-produced secretory protein from the Bacillus Sec pathway into the Tat pathway for protein secretion as revealed by proteogenomics. Proteomics 9, 1018-32
6. Conservation of the Pho regulon in Pseudomonas fluorescens Pf0-1. Appl. Environ. Microbiol. 72, 1910-24
7. The twin-arginine signal peptide of PhoD and the TatAd/Cd proteins of Bacillus subtilis form an autonomous Tat translocation system. J. Biol. Chem. 277, 3268-73
8. Vegetative hyphal fusion is not essential for plant infection by Fusarium oxysporum. Eukaryotic Cell 7, 162-71
9. Crystal structure of the Bacillus subtilis phosphodiesterase PhoD reveals an iron and calcium-containing active site. J. Biol. Chem. 289, 30889-99