Figure 7.

Regulation of SwHaCE diguanylate cyclase activity by SwH-NOX. Addition of 20 μM Fe(II)-unligated complex of SwH-NOX to SwHaCE causes a significant increase in the specific activity of SwHaCE. Addition of any of the Fe(II)-unligated SwH-NOX surface mutants (E16K, F17A, and E20K, all at 20 μM), however, had a weaker effect or no effect on SwHaCE activity, indicating weakened binding to SwHaCE. All assays contained 1 μM SwHaCE and 200 μM GTP as substrate. Error bars represent three independent trials on different days. A Student’s p test was conducted to determine significance. Asterisks indicate p ≤ 0.006. Each data set was compared to the activity of SwHaCE with WT SwH-NOX Fe(II).