Open AccessError-free replicative bypass of thymine glycol by the combined action of DNA polymerases κ and ζ in human cells
Author(s) -
Jung Hoon Yoon,
Gita Bhatia,
Satya Prakash,
Louise Prakash
Publication year - 2010
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.1007795107
Subject(s) - thymine , dna polymerase , dna replication , dna , polymerase , thymidine , biophysics , biology , lesion , microbiology and biotechnology , biochemistry , chemistry , medicine , psychiatry
Thymine glycol (Tg) is the most common DNA lesion of thymine induced by interaction with reactive oxygen species. Because of the addition of hydroxyl groups at C5 and C6 in a Tg lesion, the damaged base loses its aromatic character and becomes nonplanar; consequently, the C5 methyl group protrudes in an axial direction and that prevents the stacking of the 5′ base above the Tg lesion. Because Tg presents a severe block to continued synthesis by replicative DNA polymerases, we determine here how human cells manage to replicate through this lesion. Using a duplex plasmid system where bidirectional replication ensues from an origin of replication, we show that translesion synthesis (TLS) makes a prominent contribution to Tg bypass and that it occurs in a predominantly error-free fashion. Also, we provide evidence that Polκ and Polζ function together in promoting error-free replication through the lesion, and based on structural and biochemical information, we propose a role for Polκ at the insertion step and of Polζ at the extension step of Tg bypass. We discuss the implications of these observations and suggest that human cells have adapted the TLS machinery to function in a much more error-free fashion than could have been predicted from the intrinsic catalytic efficiencies and fidelities of TLS polymerases.