Distinctive activities of DNA polymerases during human DNA replication

• Published in: The FEBS journal 2006-07, Vol.273 (13), p.2984-3001
• Main Authors: Rytkönen, Anna K., Vaara, Markku, Nethanel, Tamar, Kaufmann, Gabriel, Sormunen, Raija, Läärä, Esa, Nasheuer, Heinz‐Peter, Rahmeh, Amal, Lee, Marietta Y. W. T., Syväoja, Juhani E., Pospiech, Helmut
• Format: Article
• Language: English
• Subjects: cell cycle; Chromatin - chemistry; Deoxyribonucleic acid; DNA; DNA polymerase; DNA Polymerase I - chemistry; DNA Polymerase II - chemistry; DNA Polymerase III - chemistry; DNA Replication; DNA-Directed DNA Polymerase - chemistry; DNA-Directed DNA Polymerase - physiology; electron microscopy; Fibroblasts - metabolism; HeLa Cells; Humans; Microscopy, Immunoelectron; Mimosine - pharmacology; Molecular biology; S Phase; Ultraviolet Rays; UV cross‐linking
• ISSN: 1742-464X; 1742-4658
• DOI: 10.1111/j.1742-4658.2006.05310.x

The contributions of human DNA polymerases (pols) α, δ and ε during S‐phase progression were studied in order to elaborate how these enzymes co‐ordinate their functions during nuclear DNA replication. Pol δ was three to four times more intensely UV cross‐linked to nascent DNA in late compared with early S phase, whereas the cross‐linking of pols α and ε remained nearly constant throughout the S phase. Consistently, the chromatin‐bound fraction of pol δ, unlike pols α and ε, increased in the late S phase. Moreover, pol δ neutralizing antibodies inhibited replicative DNA synthesis most efficiently in late S‐phase nuclei, whereas antibodies against pol ε were most potent in early S phase. Ultrastructural localization of the pols by immuno‐electron microscopy revealed pol ε to localize predominantly to ring‐shaped clusters at electron‐dense regions of the nucleus, whereas pol δ was mainly dispersed on fibrous structures. Pol α and proliferating cell nuclear antigen displayed partial colocalization with pol δ and ε, despite the very limited colocalization of the latter two pols. These data are consistent with models where pols δ and ε pursue their functions at least partly independently during DNA replication.