title: Cho Endonuclease Functions during DNA Interstrand Cross-Link Repair in Escherichia coli.
abstract: DNA interstrand cross-links are complex lesions that covalently link both strands of the duplex DNA. Lesion removal is proposed to be initiated via the UvrABC nucleotide excision repair complex; however, less is known about the subsequent steps of this complex repair pathway. In this study, we characterized the contribution of nucleotide excision repair mutants to survival in the presence of psoralen-induced damage. Unexpectedly, we observed that the nucleotide excision repair mutants exhibit differential sensitivity to psoralen-induced damage, with uvrC mutants being less sensitive than either uvrA or uvrB We show that Cho, an alternative endonuclease, acts with UvrAB and is responsible for the reduced hypersensitivity of uvrC mutants. We find that Cho's contribution to survival correlates with the presence of DNA interstrand cross-links, rather than monoadducts, and operates at a step after, or independently from, the initial incision during the global repair of psoralen DNA adducts from the genome.
  
  
  
  DNA interstrand cross-links are complex lesions that covalently bind to both strands of the duplex DNA and whose mechanism of repair remains poorly understood. In this study, we show that Cho, an alternative endonuclease, acts with UvrAB and participates in the repair of DNA interstrand cross-links formed in the presence of photoactivated psoralens. Cho's contribution to survival correlates with the presence of DNA interstrand cross-links and operates at a step after, or independently from, the initial incision during the repair process.
authors: Department of Biology, Portland State University, Portland, Oregon, USA.
authors: Anthonige Vidya
authors: AV
authors: Perera
authors: Department of Biology, Portland State University, Portland, Oregon, USA.
authors: James Brian
authors: JB
authors: Mendenhall
authors: Department of Biology, Portland State University, Portland, Oregon, USA.
authors: Charmain Tan
authors: CT
authors: Courcelle
authors: Department of Biology, Portland State University, Portland, Oregon, USA justc@pdx.edu.
authors: Justin
authors: J
authors: Courcelle
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism; D018736:DNA Adducts / Q000235:genetics*; D004265:DNA Helicases / Q000235:genetics / Q000378:metabolism; D004260:DNA Repair; D004269:DNA, Bacterial / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004706:Endodeoxyribonucleases / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D011564:Furocoumarins / Q000235:genetics*; D013379:Substrate Specificity
chemical_list: D018736:DNA Adducts; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D011564:Furocoumarins; C058093:UvrB protein, E coli; C056465:psoralen-DNA adduct; D004706:Endodeoxyribonucleases; C066567:UvrC protein, E coli; C448636:Cho protein, E coli; C068631:UvrA protein, E coli; D000251:Adenosine Triphosphatases; D004265:DNA Helicases