FEATURES

FAMILY

DESCRIPTION

Also known as DPOD1_HUMAN, POLD1, POLD. As the catalytic component of the trimeric (Pol-delta3 complex) and tetrameric DNA polymerase delta complexes (Pol-delta4 complex), plays a crucial role in high fidelity genome replication, including in lagging strand synthesis, and repair. Exhibits both DNA polymerase and 3'- to 5'-exonuclease activities (PubMed:16510448, PubMed:19074196, PubMed:20334433, PubMed:24035200, PubMed:24022480). Requires the presence of accessory proteins POLD2, POLD3 and POLD4 for full activity. Depending upon the absence (Pol-delta3) or the presence of POLD4 (Pol-delta4), displays differences in catalytic activity. Most notably, expresses higher proofreading activity in the context of Pol-delta3 compared with that of Pol-delta4 (PubMed:19074196, PubMed:20334433). Although both Pol-delta3 and Pol-delta4 process Okazaki fragments in vitro, Pol-delta3 may be better suited to fulfill this task, exhibiting near-absence of strand displacement activity compared to Pol-delta4 and stalling on encounter with the 5'-blocking oligonucleotides. Pol-delta3 idling process may avoid the formation of a gap, while maintaining a nick that can be readily ligated (PubMed:24035200). Along with DNA polymerase kappa, DNA polymerase delta carries out approximately half of nucleotide excision repair (NER) synthesis following UV irradiation (PubMed:20227374). Under conditions of DNA replication stress, in the presence of POLD3 and POLD4, may catalyze the repair of broken replication forks through break-induced replication (BIR) (PubMed:24310611). Involved in the translesion synthesis (TLS) of templates carrying O6-methylguanine, 8oxoG or abasic sites (PubMed:19074196, PubMed:24191025). Component of the tetrameric DNA polymerase delta complex (Pol-delta4), which consists of POLD1/p125, POLD2/p50, POLD3/p66/p68 and POLD4/p12, with POLD1 bearing both DNA polymerase and 3' to 5' proofreading exonuclease activities (PubMed:11595739, PubMed:12522211, PubMed:17317665, PubMed:22801543). Within Pol-delta4, directly interacts with POLD2 and POLD4 (PubMed:11328591, PubMed:12403614, PubMed:16510448). Following genotoxic stress by DNA-damaging agents, such as ultraviolet light and methyl methanesulfonate, or by replication stress induced by treatment with hydroxyurea or aphidicolin, Pol-delta4 is converted into a trimeric form of the complex (Pol-delta3) by POLD4 degradation. Pol-delta3 is the major form at S phase replication sites and DNA damage sites (PubMed:22801543, PubMed:17317665). POLD1 displays different catalytic properties depending upon the complex it is found in (PubMed:17317665). It exhibits higher proofreading activity and fidelity than Pol-delta4, making it particularly well suited to respond to DNA damage (PubMed:19074196, PubMed:20334433). Directly interacts with PCNA, as do POLD3 and POLD4; this interaction stimulates Pol-delta4 polymerase activity (PubMed:11328591, PubMed:12403614, PubMed:12522211, PubMed:16510448, PubMed:24022480, PubMed:24939902). As POLD2 and POLD4, directly interacts with WRNIP1; this interaction stimulates DNA polymerase delta-mediated DNA synthesis, independently of the presence of PCNA. This stimulation may be due predominantly to an increase of initiation frequency and also to increased processivity (PubMed:15670210). Also observed as a dimeric complex with POLD2 (Pol-delta2 complex). Pol-delta2 is relatively insensitive to the PCNA stimulation (2-5-fold) compared to Pol-delta4 that is stimulated by over 50-fold (PubMed:12403614). The DNA polymerase delta complex interacts with POLDIP2; this interaction is probably mediated through direct binding to POLD2 (PubMed:12522211). Interacts with CIAO1 (PubMed:23891004). Interacts with POLDIP2 (PubMed:24191025).

EXTERNAL LINKS

POLD1

DNA polymerase delta catalytic subunit

POLD1

Molecular Synopsis