TY - JOUR
T1 - Evidence that processing of ribonucleotides in DNA by topoisomerase 1 is leading-strand specific
AU - Williams, Jessica S.
AU - Clausen, Anders R.
AU - Lujan, Scott A.
AU - Marjavaara, Lisette
AU - Clark, Alan B.
AU - Burgers, Peter M.
AU - Chabes, Andrei
AU - Kunkel, Thomas A.
N1 - Funding Information:
We thank K. Bebenek, C. Orebaugh and S. Williams for helpful comments on the manuscript and all members of the Kunkel laboratory for thoughtful discussions. We acknowledge the US National Institute of Environmental Health Sciences (NIEHS) Molecular Genetics Core Facility for sequence analysis of 5-FOA–resistant mutants and the NIEHS Flow Cytometry Center for fluorescence-activated cell-sorting analysis. This work was supported by project Z01 ES065070 to T.A.K. from the Division of Intramural Research of the US National Institutes of Health (NIH), NIEHS, by the Swedish Cancer Society to A.C. and by US NIH grant GM032431 to P.M.B.
Publisher Copyright:
© 2015 Nature America, Inc. All rights reserved.
PY - 2015/4/7
Y1 - 2015/4/7
N2 - Ribonucleotides incorporated during DNA replication are removed by RNase H2-dependent ribonucleotide excision repair (RER). In RER-defective yeast, topoisomerase 1 (Top1) incises DNA at unrepaired ribonucleotides, initiating their removal, but this is accompanied by RNA-DNA-damage phenotypes. Here we show that these phenotypes are incurred by a high level of ribonucleotides incorporated by a leading strand-replicase variant, DNA polymerase (Pol) ε, but not by orthologous variants of the lagging-strand replicases, Pols α or δ. Moreover, loss of both RNases H1 and H2 is lethal in combination with increased ribonucleotide incorporation by Pol ε but not by Pols α or δ. Several explanations for this asymmetry are considered, including the idea that Top1 incision at ribonucleotides relieves torsional stress in the nascent leading strand but not in the nascent lagging strand, in which preexisting nicks prevent the accumulation of superhelical tension.
AB - Ribonucleotides incorporated during DNA replication are removed by RNase H2-dependent ribonucleotide excision repair (RER). In RER-defective yeast, topoisomerase 1 (Top1) incises DNA at unrepaired ribonucleotides, initiating their removal, but this is accompanied by RNA-DNA-damage phenotypes. Here we show that these phenotypes are incurred by a high level of ribonucleotides incorporated by a leading strand-replicase variant, DNA polymerase (Pol) ε, but not by orthologous variants of the lagging-strand replicases, Pols α or δ. Moreover, loss of both RNases H1 and H2 is lethal in combination with increased ribonucleotide incorporation by Pol ε but not by Pols α or δ. Several explanations for this asymmetry are considered, including the idea that Top1 incision at ribonucleotides relieves torsional stress in the nascent leading strand but not in the nascent lagging strand, in which preexisting nicks prevent the accumulation of superhelical tension.
UR - http://www.scopus.com/inward/record.url?scp=84926408181&partnerID=8YFLogxK
U2 - 10.1038/nsmb.2989
DO - 10.1038/nsmb.2989
M3 - Article
C2 - 25751426
AN - SCOPUS:84926408181
SN - 1545-9993
VL - 22
SP - 291
EP - 297
JO - Nature Structural and Molecular Biology
JF - Nature Structural and Molecular Biology
IS - 4
ER -