DNA deoxyribophosphodiesterase of Escherichia coli is associated with exonuclease I.
DNA deoxyribophosphodiesterase (dRpase) of E. coli catalyzes the release of deoxyribose-phosphate moieties following the cleavage of DNA at an apurinic/apyrimidinic (AP) site by either an AP endonuclease or AP lyase. Exonuclease I is a single-strand specific DNA nuclease which affects the expression of recombination and repair pathways in E. coli. We show here that a major dRpase activity in E. coli is associated with the exonuclease I protein. Highly purified exonuclease I isolated from an over-producing stain contains high levels of dRpase activity; it catalyzes the release of deoxyribose-5-phosphate from an AP site incised with endonuclease IV of E. coli and the release of 4-hydroxy-2-pentenal-5-phosphate from an AP site incised by the AP lyase activity of endonuclease III of E. coli. A strain containing a deletion of the sbcB gene showed little dRpase activity; the activity could be restored by transformation of the strain with a plasmid containing the sbcB gene. The dRpase activity isolated from an overproducing stain was increased 70-fold as compared to a normal sbcB+ strain (AB3027). These results suggest that the dRpase activity may be important in pathways for both DNA repair and recombination.
Sandigursky
M
M
Department of Radiology, Albert Einstein College of Medicine, Bronx, NY 10461.
Franklin
W A
WA
D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D005090:Exodeoxyribonucleases / Q000302:isolation & purification* / Q000378:metabolism*; D017353:Gene Deletion; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D016296:Mutagenesis; D010727:Phosphoric Diester Hydrolases / Q000302:isolation & purification* / Q000378:metabolism*; D013379:Substrate Specificity
D005090:Exodeoxyribonucleases; C028450:exodeoxyribonuclease I; C058246:DNA deoxyribophosphodiesterase; D010727:Phosphoric Diester Hydrolases