Abstract
Many types of DNA damage block replication fork progression during DNA synthesis because replicative DNA polymerases are unable to bypass altered DNA bases. To overcome this block, cells employ specialized translesion synthesis (TLS) polymerases, which can insert nucleotides opposite damaged bases. The process requires multiple polymerase switching events which include replacement of the high-fidelity DNA polymerase by TLS polymerase in the replication machinery arrested at the primer terminus and selection of a most suitable one among several TLS polymerases having different substrate specificity. The protein-protein interactions between TLS polymerases must play an important role for this process. Drosophila dPolh, dPoli, dRev1 are the members of Y-family DNA polymerase known to carry out TLS in vitro. We have searched for interactions between these TLS polymerases using yeast two-hybrid system. We demonstrated that dPolh interacts with C-terminal region of dRev1 whereas dPoli interacts with the dRev1 BRCT domain. We further localized the interaction region of dPolh by yeast two-hybrid assy and found four phenylalanine (F) residues at 26, 27, 564 and 565 are essential for the Rev1-interaction. On the other hand, we can not find such FF motif in dPoli. dPoli interact with dRev1 at two distinct domains [201-300, 558-654]. We also identified several proteins which interact with dPoli by screening the Drosophila cDNA library with yeast two-hybrid assay. Partial characterization of these proteins will be also described.
