Nuc2 activity can be measured at the cell surface.

<p><b>A</b>. Whole-cell FRET activity assay measuring Nuc2 surface function with UAMS-1 WT, <i>nuc2</i>, <i>nuc</i> and <i>nuc nuc2</i> double mutants. <b>B</b>. Cell surface nuclease activity in USA300 strain LAC WT, <i>nuc2</i>, <i>nuc</i> and <i>nuc nuc2</i> double mutants. Statistical significance (*p<0.1; **p<0.01) was determined by a Student's T-test. <b>C</b>. A collection of <i>S. aureus nuc</i> mutants tested in the same whole-cell FRET assay. The strains represented several genetic backgrounds, including (from left) Newman, USA300 strains (SF8300 and LAC), RN4220, MW2, TCH1516, COL and UAMS-1.