Polymerase and Histidinol Phosphatase domain of alpha-subunit of bacterial polymerase III at PolC gene
DNA polymerase III alphas (PolIIIAs) that contain a PHP domain have been classified into four basic groups based on phylogenetic and domain structural analyses: polC, dnaE1, dnaE2, and dnaE3. The PolC group is distinct from the other three and is clustered together. The PHP (also called histidinol phosphatase-2/HIS2) domain is associated with several types of DNA polymerases, such as PolIIIA and family X DNA polymerases, stand alone histidinol phosphate phosphatases (HisPPases), and a number of uncharacterized protein families. DNA polymerase III holoenzyme is one of the five eubacterial DNA polymerases that are responsible for the replication of the DNA duplex. The alpha subunit of DNA polymerase III core enzyme catalyzes the reaction for polymerizing both DNA strands. PolC PHP is located in different location compare to dnaE1, 2, and 3. The PHP domain has four conserved sequence motifs and and contains an invariant histidine that is involved in metal ion coordination.The PHP domain of PolC is structurally homologous to other members of the PHP family that have a distorted (beta/alpha)7 barrel fold with a trinuclear metal site on the C-terminal side of the barrel. PHP domains found in dnaEs of thermophilic origin exhibit 3'-5' exonuclease activity. In contrast, PolC PHP lacks detectable nuclease activity.
Jiyao W et al.(2023). "The conserved domain database in 2023.",