Fig. 2.

IlaC engineering strategy. (A) A subset of BphG–CyaB1 protein fusion sequences, their AC activities, and responsiveness to light. The amino acid colors correspond to the colors of protein domains shown above protein sequences. Brown, PHY domain; blue, GGDEF domain; green, AC domain; and black, interdomain linkers. Predicted secondary structure elements, α-helix, and β-strand, are shown above sequences. AC activity: +, active; −, inactive, according to the lacZ plate assays (see B). Response to light: −, no response; ↑, activation; and ↓, inactivation. (B) Images of the lacZ plate assays of AC activity. Selected E. coli BL21[DE3] (pETilaC# and pT7-ho1-1) strains from A were grown on LB agar containing X-Gal and IPTG, either in the dark (Left of center) or in the red light (Right). Blue colony color indicates cAMP–CRP-induced lacZ expression. Each strain expressing an IlaC# was plated in a sector of each of the four plates. The plating guide is in the Center. Dark-blue numbers, light-inactivated IlaC protein; red numbers, light-activated IlaC proteins. IlaC expression from pETilaC# was induced at two IPTG levels: 10 μM (Upper plates) and 50 μM (Lower plates).