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

Abstract

Translesion synthesis (TLS) is a DNA damage tolerance mechanism in which DNA lesions are bypassed by specific polymerases. To investigate the role of TLS activities in ultraviolet light-induced somatic mutations, we analyzed Arabidopsis (Arabidopsis thaliana) disruptants of AtREV3, AtREV1, and/or AtPOLH genes that encode TLS-type polymerases. The mutation frequency in rev3-1 or rev1-1 mutants decreased compared with that in the wild type, suggesting that AtPolz and AtRev1 perform mutagenic bypass events, whereas the mutation frequency in the polh-1 mutant increased, suggesting that AtPolh performs nonmutagenic bypass events with respect to ultraviolet light-induced lesions. The rev3-1 rev1-1 double mutant showed almost the same mutation frequency as the rev1-1 single mutant. The increased mutation frequency found in polh-1 was completely suppressed in the rev3-1 polh-1 double mutant, indicating that AtPolz is responsible for the increased mutations found in polh-1. In summary, these results suggest that AtPolz and AtRev1 are involved in the same (error-prone) TLS pathway that is independent from the other (error-free) TLS pathway mediated by AtPolh.

UV Damaged DNA Repair & Tolerance in Plants

“…The UV sensitivity of the rev1 rev3 double mutant is similar to that of rev3, additional evidence that the role of REV1 may be in REV3 recruitment (Takahashi et al, 2005). Analysis of mutation frequency in rev1 and rev3 mutants shows a reduction relative to wildtype rate, evidence that these genes contribute to error-prone repair (Nakagawa et al, 2011). Pol is encoded by the Arabidopsis POLH gene.…”

“…POLH mutants exhibit an increased mutation frequency, indicating a role in error-free repair. Interestingly, this increased mutation rate is suppressed in the rev3 polh double mutant, indicating that REV3 is required for the increased mutations in polh (Nakagawa et al, 2011). AtPol interacts with the Arabidopsis PCNA homologues PCNA1 and PCNA2.…”

Deletion of TLS polymerases promotes homologous recombination in Arabidopsis

“…The reversion marker uidA166G-T, which contains a G-T mutation, is activated when T-G transversion occurs. 5,6 The resulting blue GUS+ sector is scored as a reversion event. Columbia and TLS-deficient plants carrying the marker were grown in the presence of 1-2 µM geldanamycin (GDA) or control DMSO and irradiated with UVC at day 14.…”

“…4 We previously used uidA-based markers to show that DNA polymerase ζ (Pol ζ) and Rev1 bypass UV-or gamma-induced damage in an error-prone manner. 5,6 Several genes involved in the error-free postreplication repair mechanism have also been reported. 7,8 AtRAD5a, one of two Arabidopsis homologues of yeast Rad5, is involved in postreplication repair.…”

RAD5a and REV3 function in two alternative pathways of DNA-damage tolerance in Arabidopsis

“…The genetic interactions between these TLS polyermases and their activities in UV radiation induced somatic mutations have been demonstrated in Arabidopsis (Nakagawa et al, 2011). The mutation frequency in rev3 and rev1 mutants decreased compared to the wild-type, whereas the mutation frequency in polh mutant increased.…”