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Arabidopsis HEMERA/pTAC12 Initiates Photomorphogenesis by Phytochromes

2010; Cell Press; Volume: 141; Issue: 7 Linguagem: Inglês

10.1016/j.cell.2010.05.007

1097-4172

Meng Chen, Rafaelo M. Galvão, Meina Li, Brian T. Burger, Jane Bugea, Jack Bolado, Joanne Chory,

Photosynthetic Processes and Mechanisms

Summary Light plays a profound role in plant development, yet how photoreceptor excitation directs phenotypic plasticity remains elusive. One of the earliest effects of light is the regulated translocation of the red/far-red photoreceptors, phytochromes, from the cytoplasm to subnuclear foci called phytochrome nuclear bodies. The function of these nuclear bodies is unknown. We report the identification of hemera , a seedling lethal mutant of Arabidopsis with altered phytochrome nuclear body patterns. hemera mutants are impaired in all phytochrome responses examined, including proteolysis of phytochrome A and phytochrome-interacting transcription factors. HEMERA was identified previously as pTAC12, a component of a plastid complex associated with transcription. Here, we show that HEMERA has a function in the nucleus, where it acts specifically in phytochrome signaling, is predicted to be structurally similar to the multiubiquitin-binding protein, RAD23, and can partially rescue yeast rad23 mutants. Together, these results implicate phytochrome nuclear bodies as sites of proteolysis. PaperFlick