Current Biology
Volume 15, Issue 7, 12 April 2005, Pages 637-642
Journal home page for Current Biology

Regulation of Phytochrome B Nuclear Localization through Light-Dependent Unmasking of Nuclear-Localization Signals

https://doi.org/10.1016/j.cub.2005.02.028Get rights and content
Under an Elsevier user license
open archive

Summary

Phytochromes are red and far-red photoreceptors that regulate plant growth and development in response to environmental light cues. Phytochromes exist in two photo-interconvertible conformational states: an inactive Pr form and an active Pfr form. The alteration of phytochromes’ subcellular location functions as a major regulatory mechanism of their biological activities [1, 2, 3]. Whereas phytochromes in the Pr form localize in the cytoplasm, phytochromes in the Pfr form accumulate in the nucleus, where they interact with transcription factors to regulate gene expression [1, 4]. The molecular details of the regulation of phytochrome translocation by light are poorly understood. Using Arabidopsis phyB as a model, we demonstrate that the C-terminal PAS-related domain (PRD) is both necessary and sufficient for phyB nuclear import and that the entire C terminus is required for nuclear-body (NB) localization. We also show that phyB’s N-terminal bilin lyase domain (BLD) and PHY domain interact directly with the PRD in a light-dependent manner. In vivo localization studies indicate that BLD-PHY is sufficient to regulate phyB’s nuclear accumulation. For phyB nuclear localization, our results suggest a molecular mechanism in which the nuclear-localization signal in the PRD is masked by interactions with phyB’s chromophore-attachment domains and unmasked by light-dependent conformational changes.

Cited by (0)

3

These authors contributed equally to this work.

4

Present address: Francis Parker School, 6501 Linda Vista Road, San Diego, California 92111.