title: The isomerization of the UvrB-DNA preincision complex couples the UvrB and UvrC activities.
abstract: In Escherichia coli nucleotide excision repair, the UvrB-DNA preincision complex plays a key role, linking adduct recognition to incision. We previously showed that the efficiency of the incision is inversely related to the stability of the preincision complex. We postulated that an isomerization reaction converts [UvrB-DNA], stable but incompetent for incision, into the [UvrB-DNA]' complex, unstable and competent for incision. Here, we identify two parameters, negative supercoiling and presence of a nick at the fifth phosphodiester bond 3' to the lesion, that accelerate the isomerization leading to an increasing incision efficiency. We also show that the [UvrB-DNA] complex is more resistant to a salt concentration increase than the [UvrB-DNA]' complex. Finally, we report that the [UvrB-DNA]' is recognized by UvrC. These data suggest that the isomerization reaction leads to an exposure of single-stranded DNA around the lesion. This newly exposed single-stranded DNA serves as a binding site and substrate for the UvrC endonuclease. We propose that the isomerization reaction is responsible for coupling UvrB and UvrC activities and that this reaction corresponds to the binding of ATP.
authors.affiliation: CNRS, Cancérogenèse Moléculaire et Structurale, ESBS conventionnée avec I'Université Louis Pasteur de Strasbourg UPR 9003, Boulevard Sébastien Brandt, 67400 Strasbourg-Illkirch, France.
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Delagoutte
authors.forename: Robert P P
authors.initials: RP
authors.lastname: Fuchs
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Bertrand-Burggraf
mesh_terms: D015073:2-Acetylaminofluorene / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000378:metabolism; D004265:DNA Helicases / Q000378:metabolism*; D004260:DNA Repair; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004278:DNA, Superhelical / Q000737:chemistry / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D004706:Endodeoxyribonucleases / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D007536:Isomerism; D009690:Nucleic Acid Conformation; D009838:Oligodeoxyribonucleotides / Q000378:metabolism*; D010957:Plasmids; D021122:Protein Subunits
chemical_list: D004269:DNA, Bacterial; D004278:DNA, Superhelical; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D009838:Oligodeoxyribonucleotides; D021122:Protein Subunits; C058093:UvrB protein, E coli; D015073:2-Acetylaminofluorene; D004706:Endodeoxyribonucleases; C066567:UvrC protein, E coli; D000251:Adenosine Triphosphatases; D004265:DNA Helicases