Endonucleases That May Recognize the ssDNA-Backbone Structure: Purification from Sf9 Cells and Characterization

Abstract

Endonucleases that cleave ssDNA under conditions that minimize the formation of secondary structures were detected in Spodoptera frugiperda Sf9 cells. One endonuclease was purified from Sf9 cells and another from Sf9 cells infected by baculoviruses. Polynucleotides containing an A- or T-tract, or a CAP binding region were digested in the presence of ATP at low Mg ions with these two nucleases. ATP could be replaced by citrate but not by EDTA. The cleavage patterns were different from those obtained with endonuclease I and exonuclease VII of Escherichia coli. The cleavages were dependent on the sequence of the polynucleotides but not associated with specific bases. EndoSfV cleaved mainly AT-rich regions.