Roles of Arabidopsis AtREV1 and AtREV7 in Translesion Synthesis

Abstract

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 z. 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, g-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.

DNA polymerase zeta (pol ζ) in higher eukaryotes

“…Arabidopsis with the mutant Rev3 were also more sensitive than normal plants to mitomycin C and to ionizing radiation [89]. Disruption of the Arabidopsis Rev1 and Rev7 genes has also been performed [91]. The phenotype of the Rev7 disruption is not identical to the Rev3 disruption; for example, Arabidopsis Rev7 mutants are not hypersensitive to ultraviolet-B radiation [91].…”

“…Disruption of the Arabidopsis Rev1 and Rev7 genes has also been performed [91]. The phenotype of the Rev7 disruption is not identical to the Rev3 disruption; for example, Arabidopsis Rev7 mutants are not hypersensitive to ultraviolet-B radiation [91]. …”

Role of AtPolζ, AtRev1, and AtPolη in UV Light-Induced Mutagenesis in Arabidopsis

“…When the rev3-1 and rev1-1 mutants were grown under longterm UV-B light exposure, their fresh weights were similarly inhibited (Takahashi et al, 2005). Furthermore, the reversion frequencies in both rev3-1 and rev1-1 mutants were lower compared with that of the wild type (Fig.…”

“…In Arabidopsis (Arabidopsis thaliana), we and other groups have isolated several genes encoding TLS-type polymerase homologs: AtREV3, AtREV7, AtREV1, AtPOLH, and AtPOLK (Sakamoto et al, 2003;García-Ortiz et al, 2004;Takahashi et al, 2005;Santiago et al, 2006). AtREV3 and AtREV7 encode a catalytic subunit and a regulatory subunit of AtPolz, respectively.…”

“…AtPolh, encoded by AtPOLH, bypasses cyclobutane pyrimidine dimers with comparable activity to human or yeast Polh (Anderson et al, 2008;Hoffman et al, 2008). AtREV3-, AtREV7-, AtREV1-, or AtPOLH-disrupted plants are more sensitive to UV light exposure compared with wild-type plants, although the levels of sensitivity differ (Sakamoto et al, 2003;Takahashi et al, 2005;Curtis and Hays, 2007;Anderson et al, 2008), suggesting that these genes play a role in conferring tolerance to UV light-induced damage.…”