Roles of arabidopsis AtREV1 and AtREV7 in translesion synthesis

Plants have mechanisms for repairing and tolerating detrimental effects by various DNA damaging agents. A tolerance pathway that has been predicted to be present in higher plants is translesion synthesis ( TLS), which is catalyzed by polymerases. In Arabidopsis ( Arabidopsis thaliana), however, the only gene known to be involved in TLS is the Arabidopsis homolog of REV3, AtREV3, which is a putative catalytic subunit of Arabidopsis DNA polymerase xi. A disrupted mutant of AtREV3, rev3, was previously found to be highly sensitive to ultraviolet- B ( UV- B) and various DNA damaging agents. REV1 and REV7 are thought to be components of translesion synthesis in plants. In this study, we identified the Arabidopsis homologs of REV1 and REV7 ( AtREV1 and AtREV7). Several mutants carrying disrupted AtREV1 and AtREV7 genes were isolated from Arabidopsis T- DNA- inserted lines. An AtREV1- disrupted mutant, rev1, was found to be moderately sensitive to UV- B and DNA cross- linkers. A rev1rev3 double mutant, like rev3, showed high sensitivity to UV- B, gamma- rays, and DNA crosslinkers. An AtREV7- disrupted mutant, rev7, was possibly sensitive to cis- diamminedichloroplatinum( II), a kind of DNA crosslinker, but it was not sensitive to acute UV- B and g- ray irradiation. On the other hand, the aerial growth of rev7, like the aerial growth of rev1 and rev3, was inhibited by long- term UV- B. These results suggest that a TLS mechanism exists in a higher plant and show that AtREV1 and AtREV7 have important roles in tolerating exposure to DNA- damaging agents.