Pathways & interactions
Histidine phosphatase superfamily, clade-2 (IPR000560)
Short name: His_Pase_clade-2
The histidine phosphatase superfamily is so named because catalysis centres on a conserved His residue that is transiently phosphorylated during the catalytic cycle. Other conserved residues contribute to a 'phosphate pocket' and interact with the phospho group of substrate before, during and after its transfer to the His residue. Structure and sequence analyses show that different families contribute different additional residues to the 'phosphate pocket' and, more surprisingly, differ in the position, in sequence and in three dimensions, of a catalytically essential acidic residue. The superfamily may be divided into two main branches. The relationship between the two branches is not evident by (PSI-)BLAST but is clear from more sensitive sequence searches and structural comparisons [PMID: 18092946].
The smaller clade-2 is composed mainly of acid phosphatases and phytases. Acid phosphatases are a heterogeneous group of proteins that hydrolyse phosphate esters, optimally at low pH. The catalytic functions of these proteins include phytase, glucose-1-phosphatase and multiple inositol polyphosphate phosphatase. Fungal phytases are histidine acid phosphatases that catalyze the hydrolysis of phytate (myo-inositol hexakisphosphate) to myo-inositol and inorganic phosphate [PMID: 8387447, PMID: 25132310].
Included in this group are:
- Escherichia coli pH 2.5 acid phosphatase (gene appA).
- E. coli glucose-1-phosphatase (EC:18.104.22.168) (gene agp).
- Yeast constitutive and repressible acid phosphatases (genes PHO3 and PHO5).
- Schizosaccharomyces pombe acid phosphatase (gene pho1).
- Aspergillus awamori phytases A and B (EC:22.214.171.124) (gene phyA and phyB).
- Mammalian lysosomal and prostatic acid phosphatase.
- Several Caenorhabditis elegans hypothetical proteins.