InterPro domain: IPR016195

This entry represents a PHP-like (Polymerase and Histidinol Phosphatase) domain, the catalytic site of which has four motifs with conserved histidine residues. This domain has a 7-stranded beta/alpha barrel fold; this structure shows some similarity to the TIM-barrel fold metallohydrolases. PHP-like domains are found in alpha-subunit of bacterial DNA polymerase III ( 2.7.7.7 ) and family X DNA polymerases in addition to histidinol phosphatase ( 3.1.3.15 ) [ 1 ]. Proteins carrying a distorted (alpha/beta)7 barrel PHP-like fold include the hypothetical protein YcdX from Escherichia coli (which contains a trinuclear metal-binding site on the C-terminal side of the barrel) [ 2 ], as well as ribonuclease P protein component 3 (Rnp3) ( 3.1.26.5 ) from Pyrococcus horikoshii (no metal site on the C-terminal side of the barrel) [ 3 ].

1. Crystal structure of monofunctional histidinol phosphate phosphatase from Thermus thermophilus HB8. Biochemistry 46, 12618-27
2. Crystal structure of the Escherichia coli YcdX protein reveals a trinuclear zinc active site. Proteins 51, 315-8
3. Crystal structure of the ribonuclease P protein Ph1877p from hyperthermophilic archaeon Pyrococcus horikoshii OT3. Biochem. Biophys. Res. Commun. 319, 787-94