A new mammalian DNA polymerase with 3' to 5' exonuclease activity: DNA polymerase δ

Abstract

A new species of DNA polymerase has been purified more than 10 000-fold from the cytoplasm of erythroid hyperplastic bone marrow. This DNA polymerase, in contrast to previously described eukaryotic DNA polymerases, is associated with a very active 3' to 5' exonuclease activity. Similar to the 3' to 5' exonuclease activity associated with prokaryotic DNA polymerases, this enzyme catalyzes the removal of 3'-terminal nucleotides from DNA, as well as a template-dependent conversion of deoxyribonucleoside triphosphates to monophosphates. The exonuclease activity is not separable from the DNA polymerase activity by chromatography on DEAE-Sephadex or hydroxylapatite, and upon sucrose density gradient centrifugation the two activities cosediment at 7 S or at 11 S depending on the ionic strength. Both exonuclease and polymerase activities have identical rates of heat inactivation and both are equally sensitive to hemin and Rifamycin AF/013, inhibitors of DNA synthesis that act by binding to DNA polymerase and causing its dissociation from its template/primer. These results are consistent with the coexistence of two enzyme activities in a single protein.

Characterization of 3'→5' exonuclease associated with DNA polymerase of silkworm nuclear polyhedrosis virus

“…6). The identical kinotics of heat denaturation were reported earlier for polymerase and exonuclease activities of phage 029 DNA polymerase ( 25 ), herpes virus DIA polymerase ( 10,12 ), vaccinia virus DNA polymerase ( 13 ) and alian DNA polymerase 6S ( 15 ). The aphidicolin-sensitivity of 3'*5' exonuclease also indicates that the exonuclease is associated with BINPV Pol.…”

DNA polymerases alpha, delta, and epsilon: three distinct enzymes from HeLa cells.

“…Like pol 8, pol III prefers poly(dA-dT) primer/ template, has low processivity with poly(dA)-oligo(dT), and has processivity and activity increased by either yeast or mammalian PCNA (29). The subunit composition of pol III (19,26,30) also appears at this time to resemble that of HeLa pol 8. Yeast pol II, conversely, is not especially affected by PCNA, is highly processive with poly(dA)-oligo(dT) (31,32), and shows salt effects with activated DNA that resemble those of pol E of mammalian cells (29,30). The recent finding of a 200-kDa form of pol II in yeast, pol II* (33), and similar inhibitor responses and exonuclease activities also supports the similarity.…”

Regulation of human DNA polymerase delta in the cellular responses to DNA damage

“…DNA polymerase d was discovered as the first eukaryotic DNA polymerase that possessed a 3 0 -5 0 proofreading exonuclease activity, at a time when the only such proofreading enzymes known were of prokaryotic or bacteriophage origin [Byrnes et al, 1976]. Studies of polymerase delta (Pol d) preparations isolated from calf thymus [Lee et al, 1980[Lee et al, , 1981[Lee et al, , 1984 and human placenta [Lee et al, 1989[Lee et al, , 1991 led to its characterization as a heterodimer of the p125 and p50 subunits.…”