Excision of sugar-phosphate products at apurinic/apyrimidinic sites by DNA deoxyribophosphodiesterase of Escherichia coli.
It has been shown previously that the DNA deoxyribophosphodiesterase (dRpase) activity of Escherichia coli excises 2-deoxyribose 5-phosphate moieties at apurinic/apyrimidinic (AP) sites in DNA following cleavage of the DNA at the AP site by an AP endonuclease such as endonuclease IV of E coli. A second class of enzymes that cleave DNA at AP sites by a beta-elimination mechanism, AP lyases, leave a different sugar-phosphate product remaining at the AP site, which has been identified as the compound trans-4-hydroxy-2-pentenal 5-phosphate. It is shown that dRpase removes this unsaturated sugar-phosphate group following cleavage of a poly(dA-dT) substrate containing AP sites by the action of the AP lyase endonuclease III of E. coli. The Km for the removal of trans-4-hydroxy-2-pentenal 5-phosphate is 0.06 microM; the Km for the removal of 2-deoxyribose 5-phosphate is 0.17 microM. It was verified that the sugar-phosphate product removed by dRpase from the endonuclease III-cleaved substrate was trans-4-hydroxy-2-pentenal 5-phosphate by conversion of the product to the compound cyclopentane-1,2-dione. The dRpase activity is unique in its ability to remove sugar-phosphate products after cleavage by both AP endonucleases and AP lyases.
Sandigursky
M
M
Department of Radiation Oncology, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, New York 10467.
Lalezari
I
I
Franklin
W A
WA
D004269:DNA, Bacterial / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology*; D010727:Phosphoric Diester Hydrolases / Q000494:pharmacology*; D013403:Sugar Phosphates / Q000378:metabolism*
D004269:DNA, Bacterial; D013403:Sugar Phosphates; C058246:DNA deoxyribophosphodiesterase; D010727:Phosphoric Diester Hydrolases