title: The roles of DNA polymerases κ and ι in the error-free bypass of N2-carboxyalkyl-2'-deoxyguanosine lesions in mammalian cells.
abstract: To counteract the deleterious effects of DNA damage, cells are equipped with specialized polymerases to bypass DNA lesions. Previous biochemical studies revealed that DinB family DNA polymerases, including Escherichia coli DNA polymerase IV and human DNA polymerase κ, efficiently incorporate the correct nucleotide opposite some N(2)-modified 2'-deoxyguanosine derivatives. Herein, we used shuttle vector technology and demonstrated that deficiency in Polk or Poli in mouse embryonic fibroblast (MEF) cells resulted in elevated frequencies of G→T and G→A mutations at N(2)-(1-carboxyethyl)-2'-deoxyguanosine (N(2)-CEdG) and N(2)-carboxymethyl-2'-deoxyguanosine (N(2)-CMdG) sites. Steady-state kinetic measurements revealed that human DNA polymerase ι preferentially inserts the correct nucleotide, dCMP, opposite N(2)-CEdG lesions. In contrast, no mutation was found after the N(2)-CEdG- and N(2)-CMdG-bearing plasmids were replicated in POLH-deficient human cells or Rev3-deficient MEF cells. Together, our results revealed that, in mammalian cells, both polymerases κ and ι are necessary for the error-free bypass of N(2)-CEdG and N(2)-CMdG. However, in the absence of polymerase κ or ι, other translesion synthesis polymerase(s) could incorporate nucleotide(s) opposite these lesions but would do so inaccurately.
authors: From the Department of Chemistry, University of California, Riverside, California 92521, USA.
authors: Bifeng
authors: B
authors: Yuan
authors: Changjun
authors: C
authors: You
authors: Nisana
authors: N
authors: Andersen
authors: Yong
authors: Y
authors: Jiang
authors: Masaaki
authors: M
authors: Moriya
authors: Timothy R
authors: TR
authors: O'Connor
authors: Yinsheng
authors: Y
authors: Wang
mesh_terms: D000818:Animals; D002460:Cell Line; D004249:DNA Damage / Q000502:physiology*; D004260:DNA Repair / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004259:DNA-Directed DNA Polymerase / Q000235:genetics / Q000378:metabolism*; D003849:Deoxyguanosine / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051379:Mice; D000094769:DNA Polymerase iota; D000099270:Y-Family DNA Polymerases
chemical_list: D004268:DNA-Binding Proteins; D004259:DNA-Directed DNA Polymerase; D003849:Deoxyguanosine; D000094769:DNA Polymerase iota; C486862:REV3L protein, mouse; C404302:POLK protein, human; D000099270:Y-Family DNA Polymerases; C498613:Polk protein, mouse; C118285:REV3L protein, human