Y-family DNA polymerase catalyses translesion synthesis and interacts functionally with PCNA2

Anderson, H.*; Vonarx, E.*; Pastushok, L.*; Nakagawa, Mayu; Katafuchi, Atsushi*; Gruz, P.*; Rubbo, A.*; Grice, D.*; Osmond, M.*; Sakamoto, Ayako; Nomi, Takehiko*; Xiao, W.*; Kunz, B.*

We assessed the roles of and in TLS mediated UV resistance. defective mutants sensitized growth of roots and whole plants to UV radiation indicating AtPol contributes to UV resistance. alone did not complement the UV sensitivity conferred by deletion of yeast , although AtPol exhibited cyclobutane dimer bypass activity and interacted with yeast PCNA in vitro. Co-expression of and , but not , restored normal UV resistance and mutation kinetics in the mutant. A single residue difference at site 201, which lies adjacent to the lysine ubiquitylated in PCNA, appeared responsible for the inability of PCNA1 to function with AtPol in UV treated yeast. PCNA interacting protein boxes and an ubiquitin-binding motif in AtPol were found to be required for restoration of UV resistance in the mutant by and . These observations indicate AtPol can catalyse TLS past UV induced DNA damage, and link the biological activity of AtPol in UV irradiated cells to PCNA2 and PCNA-and ubiquitin-binding motifs in AtPol.