title: Release of 5'-terminal deoxyribose-phosphate residues from incised abasic sites in DNA by the Escherichia coli RecJ protein.
abstract: Excision of deoxyribose-phosphate residues from enzymatically incised abasic sites in double-stranded DNA is required prior to gap-filling and ligation during DNA base excision-repair, and a candidate deoxyribophosphodiesterase (dRpase) activity has been identified in E. coli. This activity is shown here to be a function of the E. coli RecJ protein, previously described as a 5'-->3' single-strand specific DNA exonuclease involved in a recombination pathway and in mismatch repair. Highly purified preparations of dRpase contained 5'-->3' exonuclease activity for single-stranded DNA, and homogeneous RecJ protein purified from an overproducer strain had both 5'-->3' exonuclease and dRpase activity. Moreover, E. coli recJ strains were deficient in dRpase activity. The hydrolytic dRpase function of the RecJ protein requires Mg2+; in contrast, the activity of E. coli Fpg protein, that promotes the liberation of 5'-->3'Rp residues from DNA by beta-elimination, is suppressed by Mg2+. Several other E. coli nucleases, including exonucleases I, III, V, and VII, endonucleases I, III and IV and the 5'-->3' exonuclease function of DNA polymerase I, are unable to act as a dRpase. Nevertheless, E. coli fpg recJ double mutants retain capacity to repair abasic sites in DNA, indicating the presence of a back-up excision function.
authors.affiliation: Imperial Cancer Research Fund, Clare Hall Laboratories, South Mimms, Hertfordshire, UK.
authors.forename: G
authors.initials: G
authors.lastname: Dianov
authors.forename: B
authors.initials: B
authors.lastname: Sedgwick
authors.forename: G
authors.initials: G
authors.lastname: Daly
authors.forename: M
authors.initials: M
authors.lastname: Olsson
authors.forename: S
authors.initials: S
authors.lastname: Lovett
authors.forename: T
authors.initials: T
authors.lastname: Lindahl
mesh_terms: D001080:Apurinic Acid / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D004247:DNA / Q000378:metabolism*; D004260:DNA Repair; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D043223:Deoxyribonuclease IV (Phage T4-Induced); D004706:Endodeoxyribonucleases / Q000378:metabolism; D004926:Escherichia coli / Q000737:chemistry*; D029968:Escherichia coli Proteins; D043211:Exodeoxyribonuclease V; D005090:Exodeoxyribonucleases / Q000378:metabolism; D008274:Magnesium / Q000494:pharmacology; D008969:Molecular Sequence Data; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism*; D011119:Polynucleotides / Q000378:metabolism; D012267:Ribosemonophosphates / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D011119:Polynucleotides; D012267:Ribosemonophosphates; C001790:apyrimidinic acid; D001080:Apurinic Acid; D004247:DNA; D004706:Endodeoxyribonucleases; D005090:Exodeoxyribonucleases; C489467:RecJ protein, E coli; C070765:recJ protein, Bacteria; D043211:Exodeoxyribonuclease V; D043223:Deoxyribonuclease IV (Phage T4-Induced); C468972:endonuclease IV, E coli; C058246:DNA deoxyribophosphodiesterase; D010727:Phosphoric Diester Hydrolases; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D008274:Magnesium