M. Yao et Yw. Kow, INTERACTION OF DEOXYINOSINE 3'-ENDONUCLEASE FROM ESCHERICHIA-COLI WITH DNA CONTAINING DEOXYINOSINE, The Journal of biological chemistry, 270(48), 1995, pp. 28609-28616
By using a band mobility shift assay, deoxyinosine 3'-endonuclease, an
Escherichia coli enzyme which recognizes deoxyinosine, AP site, urea
residue, and base mismatches in DNA, was shown to bind tightly to deox
yinosine containing oligonucleotide duplexes, Two distinct protein-DNA
complexes were observed, the faster migrating complex (complex I, K-d
= 4 X 10(-9) M) contained one molecule of deoxyinosine 3'-endonucleas
e, while the slower migrating complex (complex II, K-d = 4 x 10(-7) M)
contained two molecules of the protein bound to every molecule of dup
lex DNA, The endonucleolytic activity of deoxyinosine 3'-endonuclease
paralleled the formation of the complex I, Interestingly, deoxyinosine
3'-endonuclease exhibited similar affinities for both the substrate a
nd the nicked duplex product and thus remained bound to the DNA after
the cleavage reaction, The formation of a stable complex required the
presence of a duplex structure 5' to the deoxyinosine residue, DNase I
footprinting revealed that deoxyinosine 3'-endonuclease protected 4-5
nucleotides 5' to the deoxyinosine, and when complex II was formed, a
t least 13 nucleotides 3' to deoxyinosine were protected. Based on the
se results, a model is proposed for the interaction of deoxyinosine 3'
-endonuclease with DNA containing deoxyinosine.