Evidence for DNA endonuclease activity in nuclear extracts from mosquito cells.
We describe a deoxyribonuclease activity from nuclear protein extracts of cultured Aedes albopictus mosquito cells. The nuclease cleaved linear and circular double-stranded DNA, first generating 3' OH single-stranded nicks followed by second strand cleavage, but had little or no exonucleolytic activity. Detection of this activity was optimal at pH 7.1, in the presence of a divalent cation (Mg2+, Ca2+, Mn2+, Ba2+). In the presence of Mg2+, Zn2+, Hg2+ and Cu2+ inhibited activity, sulfhydryl reagents and ATP had no effect. At physiological temperatures (18-35 degrees C), linear double-stranded DNA probes were preferentially cleaved near sites containing 3-6 consecutive deoxyadenine/thymine base pairs. Results from salt dependency and drug inhibition studies, combined with inspection of DNA sequence, suggested that DNA structure is among the parameters that determine preferred cleavage sites.
Department of Entomology, University of Minnesota, St Paul 55108.
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Baldridge
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Fallon
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000330:Aedes / Q000648:ultrastructure*; D000818:Animals; D001483:Base Sequence; D002413:Cations, Divalent; D002467:Cell Nucleus / Q000201:enzymology*; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism; D015342:DNA Probes; D003850:Deoxyribonuclease I / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D013439:Sulfhydryl Reagents / Q000494:pharmacology
D002413:Cations, Divalent; D015342:DNA Probes; D013439:Sulfhydryl Reagents; D000255:Adenosine Triphosphate; D004247:DNA; D003850:Deoxyribonuclease I