PMID:9388217
| Citation |
Yao, M and Kow, YW (1997) Further characterization of Escherichia coli endonuclease V. Mechanism of recognition for deoxyinosine, deoxyuridine, and base mismatches in DNA. J. Biol. Chem. 272:30774-9 |
|---|---|
| Abstract |
Endonuclease V from Escherichia coli has a wide substrate spectrum. In addition to deoxyinosine-containing DNA, the enzyme cleaves DNA containing urea residues, AP sites, base mismatches, insertion/deletion mismatches, flaps, and pseudo-Y structures. The gene coding for the enzyme was identified to be orf 225 or nfi (endonuclease five). Using enzyme purified from an overproducing strain, the deoxyinosine- and mismatch-specific activities of endonuclease V was found to have different divalent metal requirements. The affinity of the enzyme is greater than 20-fold higher for DNA containing deoxyinosine than deoxynebularine or base mismatches. Under optimal cleavage conditions, endonuclease V forms two stable complexes with DNA containing deoxyinosine, but not with DNA containing base mismatches or deoxynebularine, suggesting that the 6-keto group of hypoxanthine in DNA is critical for stable interactions with the protein. The enzyme recognizes deoxyuridine in DNA but exhibits a much lower affinity to DNA containing deoxyuridine compared with DNA containing deoxyinosine. Interestingly, deoxyuridine-specific endonuclease activity of endonuclease V has a divalent metal requirement similar to the mismatch activity. A model for the mechanism of substrate recognition is proposed to explain these different activities. |
| Links | |
| Keywords |
DNA/metabolism; Deoxyribonuclease (Pyrimidine Dimer); Deoxyribonucleosides/metabolism; Deoxyuridine/metabolism; Endodeoxyribonucleases/chemistry; Endodeoxyribonucleases/metabolism; Escherichia coli/enzymology; Inosine/analogs & derivatives; Inosine/metabolism; Magnesium Chloride/metabolism; Molecular Weight; Nucleic Acid Heteroduplexes/metabolism; Purine Nucleosides/metabolism |
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