title: Replication bypass of interstrand cross-link intermediates by Escherichia coli DNA polymerase IV.
abstract: Repair of interstrand DNA cross-links (ICLs) in Escherichia coli can occur through a combination of nucleotide excision repair (NER) and homologous recombination. However, an alternative mechanism has been proposed in which repair is initiated by NER followed by translesion DNA synthesis (TLS) and completed through another round of NER. Using site-specifically modified oligodeoxynucleotides that serve as a model for potential repair intermediates following incision by E. coli NER proteins, the ability of E. coli DNA polymerases (pol) II and IV to catalyze TLS past N(2)-N(2)-guanine ICLs was determined. No biochemical evidence was found suggesting that pol II could bypass these lesions. In contrast, pol IV could catalyze TLS when the nucleotides that are 5' to the cross-link were removed. The efficiency of TLS was further increased when the nucleotides 3' to the cross-linked site were also removed. The correct nucleotide, C, was preferentially incorporated opposite the lesion. When E. coli cells were transformed with a vector carrying a site-specific N(2)-N(2)-guanine ICL, the transformation efficiency of a pol II-deficient strain was indistinguishable from that of the wild type. However, the ability to replicate the modified vector DNA was nearly abolished in a pol IV-deficient strain. These data strongly suggest that pol IV is responsible for TLS past N(2)-N(2)-guanine ICLs.
authors.affiliation: Center for Research on Occupational and Environmental Toxicology and the Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, Oregon 97239-3098.
authors.forename: Anuradha
authors.initials: A
authors.lastname: Kumari
authors.affiliation: Center for Research on Occupational and Environmental Toxicology and the Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, Oregon 97239-3098.
authors.forename: Irina G
authors.initials: IG
authors.lastname: Minko
authors.affiliation: Center for Research on Occupational and Environmental Toxicology and the Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, Oregon 97239-3098.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Harbut
authors.affiliation: Molecular and Computational Biology Program, Department of Biological Sciences, Los Angeles, California 90089-2910.
authors.forename: Steven E
authors.initials: SE
authors.lastname: Finkel
authors.affiliation: Molecular and Computational Biology Program, Department of Biological Sciences, Los Angeles, California 90089-2910; Department of Chemistry, University of Southern California, Los Angeles, California 90089-2910.
authors.forename: Myron F
authors.initials: MF
authors.lastname: Goodman
authors.affiliation: Center for Research on Occupational and Environmental Toxicology and the Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, Oregon 97239-3098. Electronic address: lloydst@ohsu.edu.
authors.forename: R Stephen
authors.initials: RS
authors.lastname: Lloyd
mesh_terms: D002384:Catalysis; D004257:DNA Polymerase II / Q000235:genetics / Q000378:metabolism; D019951:DNA Polymerase beta / Q000235:genetics / Q000378:metabolism; D004260:DNA Repair / Q000502:physiology*; D004261:DNA Replication / Q000502:physiology*; D004269:DNA, Bacterial / Q000096:biosynthesis* / Q000235:genetics; D004259:DNA-Directed DNA Polymerase / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D011995:Recombination, Genetic / Q000502:physiology*
chemical_list: D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D004257:DNA Polymerase II; D019951:DNA Polymerase beta; C120926:DNA polymerase V, E coli; D004259:DNA-Directed DNA Polymerase