| 1. |
- Sparks, Justin L, et al.
(författare)
-
RNase H2-Initiated Ribonucleotide Excision Repair
- 2012
-
Ingår i: Molecular Cell. - : Elsevier BV. - 1097-2765 .- 1097-4164. ; 47:6, s. 980-986
-
Tidskriftsartikel (refereegranskat)abstract
- Ribonucleotides are incorporated into DNA by the replicative DNA polymerases at frequencies of about 2 per kb, which makes them by far the most abundant form of potential DNA damage in the cell. Their removal is essential for restoring a stable intact chromosome. Here, we present a complete biochemical reconstitution of the ribonucleotide excision repair (RER) pathway with enzymes purified from Saccharomyces cerevisiae. RER is most efficient when the ribonucleotide is incised by RNase H2, and further excised by the flap endonuclease FEN1 with strand displacement synthesis carried out by DNA polymerase δ, the PCNA clamp, its loader RFC, and completed by DNA ligase I. We observed partial redundancy for several of the enzymes in this pathway. Exo1 substitutes for FEN1 and Pol ε for Pol δ with reasonable efficiency. However, RNase H1 fails to substitute for RNase H2 in the incision step of RER.
|
|
| 2. |
- Williams, Jessica S., et al.
(författare)
-
Topoisomerase 1-Mediated Removal of Ribonucleotides from Nascent Leading-Strand DNA
- 2013
-
Ingår i: Molecular Cell. - : Cell Press. - 1097-2765 .- 1097-4164. ; 49:5, s. 1010-1015
-
Tidskriftsartikel (refereegranskat)abstract
- RNase H2-dependent ribonucleotide excision repair (RER) removes ribonucleotides incorporated during DNA replication. When RER is defective, ribonucleotides in the nascent leading strand of the yeast genome are associated with replication stress and genome instability. Here, we provide evidence that topoisomerase 1 (Top1) initiates an independent form of repair to remove ribonucleotides from genomic DNA. This Top1-dependent process activates the S phase checkpoint. Deleting TOP1 reverses this checkpoint activation and also relieves replication stress and genome instability in RER-defective cells. The results reveal an additional removal pathway for a very common lesion in DNA, and they imply that the "dirty" DNA ends created when Top1 incises ribonucleotides in DNA are responsible for the adverse consequences of ribonucleotides in RNase H2-defective cells.
|
|
