A site-specific single strand endonuclease activity induced by NYs-1 virus infection of aChlorella-like green alga

Abstract
A site-specific endonuclease was isolated from a eukaryotic Chlorella -like green alga infected with the dsDNA-containing virus NYs-1. The enzyme recognizes the sequence 5'-CC-3' and cleaves 5' to the first C. It cleaves 5'-C m C-3' sequences but not 5'- m CC-3' sequences. The enzyme creates breaks in dsDNA whenever two 5'-CC-3' sequences on opposite strands are close enough for the two strands to separate; when the 5'-CC-3' sequences on opposite strands are further apart only a portion of the strands separate. Consequently, NYs-1 endonuclease does not produce a completely stable DNA digestion pattern. The enzyme probably does not cleave ssDNA and definitely does not cleave ssRNA or dsRNA.