Figure 8.

Hypothetical Model of the Light-Dependent Regulation of dsCYC2 and Cell Cycle Onset in P. tricornutum.

Upon light exposure, the LOV domain of AUREO1a is changed from the dark state (gray) into the light state (yellow) through cysteinyl-FMN adduct formation. This induces a conformational change in the homodimer protein complex, resulting in the binding of the bZIP domains to the promoter of dsCYC2. Binding of both AUREO1a and bZIP10 homodimers to different regulatory elements in the dsCYC2 promoter results in the synergistic activation of dsCYC2 and leads to the onset of the cell cycle.