A Knockout of the Photoreceptor PtAureo1a Results in Altered Diel Expression of Diatom Clock Components.

Plants and algae use light not only for driving photosynthesis but also to sense environmental cues and to adjust their circadian clocks via photoreceptors. Aureochromes are blue-light-dependent photoreceptors that also function as transcription factors, possessing both a LOV and a bZIP domain. Aureochromes so far have only been detected in Stramenopile algae, which include the diatoms.

Functional demonstration of Aureochrome 1a proteasomal degradation after blue light incubation in the diatom Phaeodactylum tricornutum.

Aureochromes (AUREOs) are both blue light photoreceptors and transcription factors found in diatoms and related algal groups that play a critical role in regulating gene and cell physiology. One of the AUREOs in the diatom Phaeodactylum tricornutum, PtAUREO1a, has been demonstrated to significantly influence global cellular transcription upon blue light exposure. PtAUREO1a itself is highly regulated on the gene transcription level, depending on the light conditions.

The Aureochrome Photoreceptor PtAUREO1a Is a Highly Effective Blue Light Switch in Diatoms.

Aureochromes represent a unique type of blue light photoreceptors that possess a blue light sensing flavin-binding LOV-domain and a DNA-binding bZIP domain, thus being light-driven transcription factors. The diatom , a member of the essential marine primary producers, possesses four aureochromes (PtAUREO1a, 1b, 1c, 2). Here we show a dramatic change in the global gene expression pattern of wild-type cells after a shift from red to blue light.