DNA polymerase η contributes to genome-wide lagging strand synthesis

Abstract

DNA polymerase η (pol η) is best known for its ability to bypass UV-induced thymine–thymine (T–T) dimers and other bulky DNA lesions, but pol η also has other cellular roles. Here, we present evidence that pol η competes with DNA polymerases α and δ for the synthesis of the lagging strand genome-wide, where it also shows a preference for T–T in the DNA template. Moreover, we found that the C-terminus of pol η, which contains a PCNA-Interacting Protein motif is required for pol η to function in lagging strand synthesis. Finally, we provide evidence that a pol η dependent signature is also found to be lagging strand specific in patients with skin cancer. Taken together, these findings provide insight into the physiological role of DNA synthesis by pol η and have implications for our understanding of how our genome is replicated to avoid mutagenesis, genome instability and cancer.

Learning mutational signatures and their multidimensional genomic properties with TensorSignatures

“…As a further distinction, weakly clustered TLS signature TS14 can be found in more than 15 cancer types, suggesting a broad involvement of this mutagenic process in resolving endogenous and exogenous DNA alterations 28 . Polη has also been described to compete with lagging strand DNA synthesis 38 , which is further corroborated by the fact that TS14 displays a mild replicational strand bias (RSB=0.9; Fig. 2b ).…”

Impact of 1,N6-ethenoadenosine, a damaged ribonucleotide in DNA, on translesion synthesis and repair

“…The TLS process has garnered considerable attention due to the tolerance of damage in DNA in an errorfree or error-prone manner (39,40). TLS also plays an important role in tolerance of ribonucleotides in DNA, and the main key player is hpol η (especially in dealing with lagging strands derived from Okazaki fragments) (16,24,38,(41)(42)(43)(44)(45)(46). Studies with 8-oxo-rG in DNA indicate that hpol η is required for the tolerance of this adduct (24).…”

One, No One, and One Hundred Thousand: The Many Forms of Ribonucleotides in DNA

“…As already discussed, also the S. cerevisiae polη-F35A steric-gate mutant seems to incorporate polyribonucleotide tracts in DNA at a high rate, leaving a specific 1 bp deletion signature, when not removed by RNase H2 [48,49]. Moreover, under particular stress conditions, also wild type replicative and/or reparative DNA polymerases may incorporate consecutive rNMPs.…”

“…Y-family polymerases as pol η and pol ι are needed for TLS of many different types of DNA lesions [43,44]. The wild type S. cerevisiae pol η just shows a minimal rate of rNMP insertion on undamaged and damaged DNA; by contrast, the steric gate mutant pol η-F35A readily incorporates the correct rNMP opposite both templates, and in vivo experiments suggest that it may catalyze the incorporation of stretches of ribonucleotides in DNA [48,49]. Moreover, genetic evidence points towards the idea that under low dNTP conditions, either the wild type pol η or, even more, pol η-F35A inserts consecutive ribonucleotides, which become toxic in the absence of RNase H activity [34].…”

“…The detection of such modified bases by PacBio single molecule, real-time (SMRT) sequencing reveals the location of ribonucleotides [177]. Moreover, by using steric-gate mutants, which incorporate more rNMPs, it has been even possible to assess the precise contribution of replicative and TLS polymerases to DNA replication [20,49,173,174,177]. To date, these approaches have been used in bacteria, archaea, and yeast cells, but they could be adapted to any organism in which RNase H activity can be modulated.…”