Figure 3.

Engineered and natural light-gated PDEs. (A) The schematic model of generating the artificial light-gated PDE, LAPD. The LAPD comprises the light sensor modules from DrBPhy (labeled by red dashed box) and PDE catalytic domain from HsPDE2A (labeled by gray dashed box). The encircled cG indicates cGMP. The chromophore is shown with encircled Bilin. The red triangle indicates the connection point. (B) The schematic model of natural light-gated PDE. The chromophore is shown with encircled ATR. In a newly discovered protist Choanoeca flexa sp. nov, the RhoPDE can be activated by light to hydrolyze cGMP and trigger the inversion to flagella-in orientation. In the dark, cGMP levels will be maintained and flagella-out orientation is kept. The lower cartoon in B is made according to [65]. LAPD: light-activated PDE; Bilin: biliverdin; PAS: Per-Arnt-Sim domain; ATR: all-trans-retinal.