I. Cloning and characterization of human DNA polymerase theta. II. Protein interactions of human damaged DNA binding protein.

摘要

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.