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. Author manuscript; available in PMC: 2014 Mar 7.
Published in final edited form as: Mol Cell. 2013 Jan 31;49(5):1010–1015. doi: 10.1016/j.molcel.2012.12.021

Figure 4. A Model Depicting Pathways of Ribonucleotide Removal from DNA.

Figure 4

Ribonucleotides incorporated into genomic DNA by Pol εare normally repaired during RER. Loss of RNase H2 activity (rnh201Δ) results in unrepaired ribonucleotides that are targets for Top1. Results from this study show that cleavage and removal of ribonucleotides from genomic DNA by Top1 is the cause of several genome instability phenotypes in yeast that include spontaneous mutagenesis, replicative stress and checkpoint activation. Genome instability may arise during processing of the “dirty” unligatable DNA ends created by Top1 cleavage, possibly generating DNA nicks, double-strand breaks (DSBs) and/or recombination. The red triangle indicates the position of the 2′,3′-cyclic phosphate.