UV light-induced DNA synthesis arrest in HeLa cells is associated with changes in phosphorylation of human single-stranded DNA-binding protein.
We show that DNA replication activity in extracts of human HeLa cells decreases following UV irradiation. Alterations in replication activity in vitro parallel the UV-induced block in cell cycle progression of these cells in culture. UV irradiation also induces specific changes in the pattern of phosphorylation of the 34 kDa subunit of a DNA replication protein, human single-stranded DNA-binding protein (hSSB). The appearance of a hyperphosphorylated form of hSSB correlates with reduced in vitro DNA replication activity in extracts of UV-irradiated cells. Replication activity can be restored to these extracts in vitro by addition of purified hSSB. These results suggest that UV-induced DNA synthesis arrest may be mediated in part through phosphorylation-related alterations in the activity of hSSB, an essential component of the DNA replication apparatus.
Carty
M P
MP
Department of Environmental Health, College of Medicine, University of Cincinnati, OH 45267-0056.
Zernik-Kobak
M
M
McGrath
S
S
Dixon
K
K
D002453:Cell Cycle; D004261:DNA Replication / Q000528:radiation effects*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D010766:Phosphorylation / Q000528:radiation effects; D051716:Replication Protein A; D014466:Ultraviolet Rays
D004268:DNA-Binding Proteins; C497167:RPA1 protein, human; D051716:Replication Protein A