Post-incision steps of nucleotide excision repair in Escherichia coli: Disassembly of the UvrBC-DNA complex by helicase II and DNA polymerase I

D. K. Orren, C. P. Selby, J. E. Hearst, A. Sancar

Research output: Contribution to journalArticlepeer-review

136 Scopus citations

Abstract

UvrA, UvrB, and UvrC initiate nucleotide excision repair by incising a damaged DNA strand on each side of the damaged nucleotide. This incision reaction is substoichiometric with regard to UvrB and UvrC, suggesting that both proteins remain bound following incision and do not "turn over." The addition of only helicase II to such reaction mixtures turns over UvrC; UvrB turnover requires the addition of helicase II, DNA polymerase I, and deoxynucleoside triphosphates. Column chromatography and psoralen photocross-linking experiments show that following incision, the damaged oligomer remains associated with the undamaged strand, UvrB, and UvrC in a postincision complex. Helicase II releases the damaged oligomer and UvrC from this complex, making repair synthesis possible; DNase I footprinting experiments show that UvrB remains bound to the resulting gapped DNA until displaced by DNA polymerase I. The specific binding of UvrB to a psoralen adduct in DNA inhibits psoralen-mediated DNA-DNA cross-linking, yet promotes the formation of UrvB-psoralen-DNA crosslinks. The discovery of psoralen-UvrB photocrosslinking offers the potential of active-site labeling.

Original languageEnglish
Pages (from-to)780-788
Number of pages9
JournalJournal of Biological Chemistry
Volume267
Issue number2
StatePublished - Jan 15 1992

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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