Figure 4. Phosphatase Activity of CrdS α1 Mutants.

CrdS WT and mutant proteins were tested for their ability to dephosphorylate CrdA∼P which was generated using [³²P] acetyl-phosphate. Bars indicate the amount of CrdA∼P remaining after a 5 minute incubation with each CrdS mutant protein. Data shown are the average of three separate experiments with error bars indicating standard deviation. Statistically significant differences in phosphatase activity are indicated by an (*), p<0.05. CrdS-WT and CrdA∼P alone were used as controls (shown at right). (A) Phosphatase activity is shown for each mutant protein generated using site-directed mutagenesis. (B) Phosphatase activity of additional mutants generated within the highly conserved region. The N482K mutant (CA domain mutant) is shown as a control.