Photobodies in Light Signaling

Abstract

One of the earliest light responses at the cellular level is the translocation of the red and far-red photoreceptors, phytochromes, from the cytoplasm to discrete subnuclear domains named phytochrome nuclear bodies or photobodies. In Arabidopsis, photobodies contain multiple photoreceptors including phytochromes, the ultraviolet-A/blue light sensing cryptochromes, and possibly the ultraviolet-B receptor UVR8. The localization of these photoreceptors to photobodies is triggered by a light-induced conformational switch to their active states. Accumulating evidence suggests that many light signaling molecules, including key transcriptional regulators and proteins involved in their degradation, are colocalized to photobodies and that failure to form photobodies results in defects in light responses. This suggests that photobodies are intimately involved in light signaling events. In this review, we will summarize recent developments related to photobodies and discuss the potential functions of photobodies in relation to light-dependent protein degradation and gene expression.