Missense mutation in the PAS2 domain of phytochrome A impairs subnuclear localization and a subset of responses

Marcelo J Yanovsky, Juan Pablo Luppi, Daniel Kirchbauer, Ouliana B Ogorodnikova, Vitally A Sineshchekov, Eva Adam, Stefan Kircher, Roberto J Staneloni, Eberhard Schäfer, Ferenc Nagy, Jorge J Casal

Research output: Contribution to journalArticlepeer-review

Abstract

Phytochrome A signaling shows two photobiologically discrete outputs: so-called very-low-fluence responses (VLFR) and high-irradiance responses (HIR). By modifying previous screening protocols, we isolated two Arabidopsis mutants retaining VLFR and lacking HIR. Phytochrome A negatively or positively regulates phytochrome B signaling, depending on light conditions. These mutants retained the negative but lacked the positive regulation. Both mutants carry the novel phyA-302 allele, in which Glu-777 (a residue conserved in angiosperm phytochromes) changed to Lys in the PAS2 motif of the C-terminal domain. The phyA-302 mutants showed a 50% reduction in phytochrome A levels in darkness, but this difference was compensated for by greater stability under continuous far-red light. phyA-302:green fluorescent protein fusion proteins showed normal translocation from the cytosol to the nucleus under continuous far-red light but failed to produce nuclear spots, suggesting that nuclear speckles could be involved in HIR signaling and phytochrome A degradation. We propose that the PAS2 domain of phytochrome A is necessary to initiate signaling in HIR but not in VLFR, likely via interaction with a specific partner.
Original languageEnglish
Pages (from-to)1591-603
Number of pages13
JournalPlant Cell
Volume14
Issue number7
DOIs
Publication statusPublished - 2002

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