Translesion synthesis and mutagenesis in higher plants

Sakamoto, Ayako; Nakagawa, Mayu; Takahashi, Shinya*; Shimizu, Kikuo*; Tanaka, Atsushi; Narumi, Issei

To survive under the challenging circumstances, plants equip themselves with damage tolerance mechanisms, such as translesion synthesis (TLS). During our attempt to isolate novel genes accounting for the UV-resistance, we found several genes that seem to be involved in TLS. These are , , and . All these disruptants were more sensitive to UV exposure than wild-type plant although the levels of sensitivity were different each other. To obtain further information about plant TLS mechanisms, we analyzed bacterially expressed AtREV1 protein . The recombinant AtREV1 protein inserted a dCMP at the opposite of AP site, but never inserted a nucleotide opposite of CPD nor 6-4 photoproducts. We also measured the UV-induced mutation frequencies in -, - or -disrupted plants. The disruption of or reduced the reversion frequency to 1/4 of the level of wild type, while the disruption of enhanced the frequency more than twice. These results suggest that UV-induced damage is processed by two competitive pathways in Arabidopsis: a more mutagenic pathway with AtREV3 and AtREV1 and a less mutagenic pathway with AtPOLH.