A genetic system for analysis of staphylococcal nuclease.

The gene encoding staphylococcal nuclease (strain Foggi) has been isolated, and its complete nucleotide sequence determined. When inserted into a derivative of plasmid pBR322, the nuc gene is expressed in Escherichia coli at a low level, and nuclease activity in individual colonies is readily assayed by a replica-plating chromogenic test. A set of plasmids with BamHI-linker "bracketed" deletions spanning the nuc gene can be used to map mutations genetically to defined segments of the gene. In combination with present methods for efficient in vitro mutagenesis, this plasmid-based genetic system can be applied to the detailed genetic analysis of this small, biochemically and biophysically well-characterized enzyme.