Journal of Photosciences

A Molecular Model for Light Signal Perception and Interdomain Crosstalk in Phytochrome Photoreceptors

Volume 7(2000), 79-86 page

ÀúÀÚ: Pill-Soon Song and Chung-Mo Park

   7-3-79.pdf (648.1K)

Keywords: chromophore  conformational changes  inter-domain signal transmission  phosphorylation  phototransformation  phytochromes


Phytochromes are red and far-red light absorbing photoreceptors for photomorphogenesis in plants.
The red/far-red wavelength reversible biliproteins are made up of two structural domains.
The light-perceiving function of the photoreceptor resides in the N-terminal domain, whereas the signal transducing regulatory function is located within the C-terminal domain.
The characteristic role of the phytochromes as photosensory molecular switches is derived from the phototransformation between two distinct spectral forms, the red light absorbing Pr and the far-red light absorbing Pfr forms.
The photoinduced Pr <-> Pfr phototransformation accompanies subtle conformational changes throughout the phytochrome molecule.
The conformational signals are subsequently transmitted to the C-terminal domain through various inter-domain crosstalks and induce the interaction of the activated C-terminal domain with phytochrome interacting factors.
Thus the interdomain crosstalks play critical roles in the photoactivation of the phytochromes.
Posttranslational modifications, such as the phosphorylation of Ser-598, are also involved in this process through conformational changes and by modulating inter-domain signaling.