The Histidine Kinase-Related Domain of Arabidopsis Phytochrome A Controls the Spectral Sensitivity and the Subcellular Distribution of the Photoreceptor

Müller, Rebecca; Fernández, Aurora Piñas; Hiltbrunner, Andreas; Schäfer, Eberhard; Kretsch, Thomas

doi:10.1104/pp.109.135988

Cited by 16 publications

(14 citation statements)

References 61 publications

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“…The fact that FHY1 homologs are widely distributed in angiosperms suggests that the mechanism uncovered in Arabidopsis may be conserved in higher plants (Genoud et al, 2008). However, interaction of phyA with FHY1/FHL alone appears to be insufficient for phyA nuclear translocation, because phyA-402, containing a missense mutation in the HKRD domain of phyA, is still capable of interacting with FHY1/FHL but does not translocate into the nucleus in R light (Muller et al, 2009).…”

Section: Far-red Elongated Hypocotyl 1 (Fhy1) and Fhy1-like (Fhl)mentioning

confidence: 99%

Phytochrome Signaling Mechanisms

Wang

et al. 2011

The Arabidopsis Book

387

342

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Phytochromes are red (R)/far-red (FR) light photoreceptors that play fundamental roles in photoperception of the light environment and the subsequent adaptation of plant growth and development. There are five distinct phytochromes in Arabidopsis thaliana, designated phytochrome A (phyA) to phyE. phyA is light-labile and is the primary photoreceptor responsible for mediating photomorphogenic responses in FR light, whereas phyB-phyE are light stable, and phyB is the predominant phytochrome regulating de-etiolation responses in R light. Phytochromes are synthesized in the cytosol in their inactive Pr form. Upon light irradiation, phytochromes are converted to the biologically active Pfr form, and translocate into the nucleus. phyB can enter the nucleus by itself in response to R light, whereas phyA nuclear import depends on two small plant-specific proteins FAR-RED ELONGATED HYPOCOTYL 1 (FHY1) and FHY1-LIKE (FHL). Phytochromes may function as light-regulated serine/threonine kinases, and can phosphorylate several substrates, including themselves in vitro. Phytochromes are phosphoproteins, and can be dephosphorylated by a few protein phosphatases. Photoactivated phytochromes rapidly change the expression of light-responsive genes by repressing the activity of CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1), an E3 ubiquitin ligase targeting several photomorphogenesis-promoting transcription factors for degradation, and by inducing rapid phosphorylation and degradation of Phytochrome-Interacting Factors (PIFs), a group of bHLH transcription factors repressing photomorphogenesis. Phytochromes are targeted by COP1 for degradation via the ubiquitin/26S proteasome pathway.

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Section: Far-red Elongated Hypocotyl 1 (Fhy1) and Fhy1-like (Fhl)mentioning

confidence: 99%

Phytochrome Signaling Mechanisms

Wang

et al. 2011

The Arabidopsis Book

387

342

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“…The C-terminal regions of plant PHY and of those prokaryotic PHY that have been sequenced are not homologous (Lamparter, 2004;Mathews, 2006); in green plants, this region comprises two PAS and single His kinase and ATPase domains ( Figure 3B), the latter two domains form the core of the His kinase-related domain (HKRD; Rockwell et al, 2006). The PAS repeats and HKRD contain sites necessary for dimerization and nuclear localization (Quail, 1997;Chen et al, 2003) and for modulating phytochrome signaling (Krall and Reed, 2000;Matsushita et al, 2003;Oka et al, 2004;Mü ller et al, 2009). Sequence conservation among the photosensory cores of plant and Synechocystis 6803 Cph1 phytochromes facilitates their alignment (Essen et al, 2008), and the alignment serves as a preliminary basis for relating positions in plant phytochromes to Cph1 structural elements ( Figure 3C).…”

Section: Synthesis Of Functional Evolutionary and Structural Datamentioning

confidence: 99%

Evolutionary Studies Illuminate the Structural-Functional Model of Plant Phytochromes

Mathews

2010

The Plant Cell

107

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A synthesis of insights from functional and evolutionary studies reveals how the phytochrome photoreceptor system has evolved to impart both stability and flexibility. Phytochromes in seed plants diverged into three major forms, phyA, phyB, and phyC, very early in the history of seed plants. Two additional forms, phyE and phyD, are restricted to flowering plants and Brassicaceae, respectively. While phyC, D, and E are absent from at least some taxa, phyA and phyB are present in all sampled seed plants and are the principal mediators of red/far-red-induced responses. Conversely, phyC-E apparently function in concert with phyB and, where present, expand the repertoire of phyB activities. Despite major advances, aspects of the structural-functional models for these photoreceptors remain elusive. Comparative sequence analyses expand the array of locus-specific mutant alleles for analysis by revealing historic mutations that occurred during gene lineage splitting and divergence. With insights from crystallographic data, a subset of these mutants can be chosen for functional studies to test their importance and determine the molecular mechanism by which they might impact light perception and signaling. In

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“…Similar to other PHYs, the distant C-terminal part of the PHYA molecule contains the His kinase-related domain, which shows homology to bacterial His kinases (Schneider-Poetsch et al, 1991;Yeh and Lagarias, 1998;Montgomery and Lagarias, 2002). The C-terminal domains of PHYA and PHYB are involved in mediating interaction with several proteins (Ni et al, 1998;Choi et al, 1999;Fankhauser et al, 1999) and in phytochrome nuclear import (Mü ller et al, 2009). Interestingly, its presence is not essential for PHYB-directed photomorphogenesis (Krall and Reed, 2000;Matsushita et al, 2003;Oka et al, 2008;Palágyi et al, 2010), whereas it seems to be required for phyA-controlled HIR signaling (Cherry et al, 1993;Wolf et al, 2011).…”

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confidence: 99%

Missense Mutation in the Amino Terminus of Phytochrome A Disrupts the Nuclear Import of the Photoreceptor

et al. 2011

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Phytochromes are the red/far-red photoreceptors in higher plants. Among them, phytochrome A (PHYA) is responsible for the far-red high-irradiance response and for the perception of very low amounts of light, initiating the very-low-fluence response. Here, we report a detailed physiological and molecular characterization of the phyA-5 mutant of Arabidopsis (Arabidopsis thaliana), which displays hyposensitivity to continuous low-intensity far-red light and shows reduced very-low-fluence response and high-irradiance response. Red light-induced degradation of the mutant phyA-5 protein appears to be normal, yet higher residual amounts of phyA-5 are detected in seedlings grown under low-intensity far-red light. We show that (1) the phyA-5 mutant harbors a new missense mutation in the PHYA amino-terminal extension domain and that (2) the complex phenotype of the mutant is caused by reduced nuclear import of phyA-5 under low fluences of far-red light. We also demonstrate that impaired nuclear import of phyA-5 is brought about by weakened binding affinity of the mutant photoreceptor to nuclear import facilitators FHY1 (for FAR-RED ELONGATED HYPOCOTYL1) and FHL (for FHY1-LIKE). Finally, we provide evidence that the signaling and degradation kinetics of constitutively nuclear-localized phyA-5 and phyA are identical. Taken together, our data show that aberrant nucleo/cytoplasmic distribution impairs light-induced degradation of this photoreceptor and that the amino-terminal extension domain mediates the formation of the FHY1/FHL/PHYA far-redabsorbing form complex, whereby it plays a role in regulating the nuclear import of phyA.

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The Histidine Kinase-Related Domain of Arabidopsis Phytochrome A Controls the Spectral Sensitivity and the Subcellular Distribution of the Photoreceptor

Cited by 16 publications

References 61 publications

Phytochrome Signaling Mechanisms

Phytochrome Signaling Mechanisms

Evolutionary Studies Illuminate the Structural-Functional Model of Plant Phytochromes

Missense Mutation in the Amino Terminus of Phytochrome A Disrupts the Nuclear Import of the Photoreceptor

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