| Living cells use DNA polymerases to replicate, recombine and repair their DNA. Here I report the discovery and characterization of the eighth human DNA polymerase, theta. The cloned cDNA is 9.1 kb long and encodes a 305 kD protein with an N-terminal putative helicase domain and a C-terminal domain that encodes an active polymerase. The level of DNA polymerase theta in a transformed human cell line increased approximately two-fold in response to treatment with mitomycin C and nitrogen mustard, suggesting that polymerase theta repairs DNA crosslinks.;Human Damaged DNA Binding protein (DDB) is involved in the cellular response to DNA damage caused by ultraviolet radiation and similar treatments. I found that the EBNA-2 protein, which mediates infection and latency of Epstein-Barr virus, interacted with the large subunit of DDB both in a yeast two-hybrid assay and in vitro. Recombinant EBNA-2 inhibited the lesion-binding activity of DDB, suggesting that viral interference with the normal function(s) of DDB represents part of the viral infection strategy. |
