DNA deoxyribophosphodiesterase of Escherichia coli is associated with exonuclease I.

Exonuclease III and endonuclease IV remove 3' blocks from DNA synthesis primers in H2O2-damaged Escherichia coli.

Escherichia coli deficient in exonuclease III (xth gene mutants) are known to be hypersensitive to hydrogen peroxide. We now show that such mutants accumulate many more DNA single-strand breaks than do wild-type bacteria upon exposure to H2O2. DNA isolated from H2O2-treated xth- cells contains strand breaks that do not efficiently support synthesis by E. coli DNA polymerase I, indicating the pr...

Molecular interactions of Escherichia coli ExoIX and identification of its associated 3′–5′ exonuclease activity

The flap endonucleases (FENs) participate in a wide range of processes involving the structure-specific cleavage of branched nucleic acids. They are also able to hydrolyse DNA and RNA substrates from the 5'-end, liberating mono-, di- and polynucleotides terminating with a 5' phosphate. Exonuclease IX is a paralogue of the small fragment of Escherichia coli DNA polymerase I, a FEN with which it ...

Processivity of DNA exonucleases.

A homopolymer system has been developed to examine the digestion strategies of DNA exonucleases. Escherichia coli exonuclease I and lambda-exonuclease, are processive enzymes. However, T7 exonuclease, spleen exonuclease, E. coli exonuclease III, the 3' leads to 5'-exonuclease of T4 DNA polymerase, and both the 3' leads to 5' and the 5' leads to 3' activity of E. coli DNA polymerase I dissociate...

A Deoxyribonucleic Acid Phosphatase-exonuclease from Escherichia Coli. Ii. Characterization of the Exonuclease Activity.

Exonuclease VII of Escherichia coli.

A new exonuclease of Escherichia coli K12, exonuclease VII, has been purified 1700-fold and characterized. The enzyme is specific for single-stranded DNA and can initiated hydrolysis at both 5' and 3' termini. It is also capable of thymine-dimer excision in vitro. The limit products of the reaction are oligonucleotides, predominantly in the range of tetramers to dodecamers. DNA is hydrolyzed b...