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Meng Chen - One of the best experts on this subject based on the ideXlab platform.
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Phytochrome activates the plastid-encoded RNA polymerase for chloroplast biogenesis via nucleus-to-plastid signaling
Nature Communications, 2019Co-Authors: Elise K. Pasoreck, Detlef Weigel, He Wang, Gregor M. Blaha, Meng ChenAbstract:Light initiates chloroplast biogenesis by activating photosynthesis-associated genes encoded by not only the nuclear but also the plastidial genome, but how photoreceptors control plastidial gene expression remains enigmatic. Here we show that the photoactivation of Phytochromes triggers the expression of photosynthesis-associated plastid-encoded genes ( PhAPG s) by stimulating the assembly of the bacterial-type plastidial RNA polymerase (PEP) into a 1000-kDa complex. Using forward genetic approaches, we identified REGULATOR OF CHLOROPLAST BIOGENESIS (RCB) as a dual-targeted nuclear/plastidial Phytochrome signaling component required for PEP assembly. Surprisingly, RCB controls PhAPG expression primarily from the nucleus by interacting with Phytochromes and promoting their localization to photobodies for the degradation of the transcriptional regulators PIF1 and PIF3. RCB-dependent PIF degradation in the nucleus signals the plastids for PEP assembly and PhAPG expression. Thus, our findings reveal the framework of a nucleus-to-plastid anterograde signaling pathway by which Phytochrome signaling in the nucleus controls plastidial transcription. Light initiates chloroplast biogenesis by controlling gene expression in plastids. Here Yoo et al. show that nuclear Phytochrome signaling triggers plastid gene expression via a novel dual-localized protein necessary for nuclear Phytochrome signaling and subsequent anterograde signaling to the plastid.
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Phytochrome activates the plastid encoded rna polymerase for chloroplast biogenesis via nucleus to plastid signaling
Nature Communications, 2019Co-Authors: Elise K. Pasoreck, Detlef Weigel, He Wang, Gregor M. Blaha, Meng ChenAbstract:Light initiates chloroplast biogenesis by activating photosynthesis-associated genes encoded by not only the nuclear but also the plastidial genome, but how photoreceptors control plastidial gene expression remains enigmatic. Here we show that the photoactivation of Phytochromes triggers the expression of photosynthesis-associated plastid-encoded genes (PhAPGs) by stimulating the assembly of the bacterial-type plastidial RNA polymerase (PEP) into a 1000-kDa complex. Using forward genetic approaches, we identified REGULATOR OF CHLOROPLAST BIOGENESIS (RCB) as a dual-targeted nuclear/plastidial Phytochrome signaling component required for PEP assembly. Surprisingly, RCB controls PhAPG expression primarily from the nucleus by interacting with Phytochromes and promoting their localization to photobodies for the degradation of the transcriptional regulators PIF1 and PIF3. RCB-dependent PIF degradation in the nucleus signals the plastids for PEP assembly and PhAPG expression. Thus, our findings reveal the framework of a nucleus-to-plastid anterograde signaling pathway by which Phytochrome signaling in the nucleus controls plastidial transcription.
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photoactivated Phytochromes interact with hemera and promote its accumulation to establish photomorphogenesis in arabidopsis
Genes & Development, 2012Co-Authors: Rafaelo M Galvao, Meina Li, Sonya M Kothadia, Jonathan D Haskel, Peter V Decker, Elise K Van Buskirk, Meng ChenAbstract:Plant development is profoundly regulated by ambient light cues through the red/far-red photoreceptors, the Phytochromes. Early Phytochrome signaling events include the translocation of Phytochromes from the cytoplasm to subnuclear domains called photobodies and the degradation of antagonistically acting Phytochrome-interacting factors (PIFs). We recently identified a key Phytochrome signaling component, HEMERA (HMR), that is essential for both Phytochrome B (phyB) localization to photobodies and PIF degradation. However, the signaling mechanism linking Phytochromes and HMR is unknown. Here we show that Phytochromes directly interact with HMR to promote HMR protein accumulation in the light. HMR binds more strongly to the active form of Phytochromes. This interaction is mediated by the photosensory domains of Phytochromes and two Phytochrome-interacting regions in HMR. Missense mutations in either HMR or phyB that alter the Phytochrome/HMR interaction can also change HMR levels and photomorphogenetic responses. HMR accumulation in a constitutively active phyB mutant (YHB) is required for YHB-dependent PIF3 degradation in the dark. Our genetic and biochemical studies strongly support a novel Phytochrome signaling mechanism in which photoactivated Phytochromes directly interact with HMR and promote HMR accumulation, which in turn mediates the formation of photobodies and the degradation of PIFs to establish photomorphogenesis.
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Phytochrome signaling mechanisms and the control of plant development
Trends in Cell Biology, 2011Co-Authors: Meng Chen, Joanne ChoryAbstract:As they emerge from the ground, seedlings adopt a photosynthetic lifestyle, which is accompanied by dramatic changes in morphology and global alterations in gene expression that optimizes the plant body plan for light capture. Phytochromes are red and far-red photoreceptors that play a major role during photomorphogenesis, a complex developmental program that seedlings initiate when they first encounter light. The earliest Phytochrome signaling events after excitation by red light include their rapid translocation from the cytoplasm to subnuclear bodies (photobodies) that contain other proteins involved in photomorphogenesis, including a number of transcription factors and E3 ligases. In the light, Phytochromes and negatively acting transcriptional regulators that interact directly with Phytochromes are destabilized, whereas positively acting transcriptional regulators are stabilized. Here, we discuss recent advances in our knowledge of the mechanisms linking Phytochrome photoactivation in the cytoplasm and transcriptional regulation in the nucleus.
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arabidopsis hemera ptac12 initiates photomorphogenesis by Phytochromes
Cell, 2010Co-Authors: Rafaelo M Galvao, Meina Li, Meng Chen, Brian Burger, Jane Bugea, Jack Bolado, Joanne ChoryAbstract: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
Peter H Quail - One of the best experts on this subject based on the ideXlab platform.
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Phytochrome functions in arabidopsis development
Journal of Experimental Botany, 2010Co-Authors: Keara A Franklin, Peter H QuailAbstract:Light signals are fundamental to the growth and development of plants. Red and far-red light are sensed using the Phytochrome family of plant photoreceptors. Individual Phytochromes display both unique and overlapping roles throughout the life cycle of plants, regulating a range of developmental processes from seed germination to the timing of reproductive development. The evolution of multiple Phytochrome photoreceptors has enhanced plant sensitivity to fluctuating light environments, diversifying Phytochrome function, and facilitating conditional cross-talk with other signalling systems. The isolation of null mutants, deficient in all individual Phytochromes, has greatly advanced understanding of Phytochrome functions in the model species, Arabidopsis thaliana. The creation of mutants null for multiple Phytochrome combinations has enabled the dissection of redundant interactions between family members, revealing novel regulatory roles for this important photoreceptor family. In this review, current knowledge of Phytochrome functions in the light-regulated development of Arabidopsis is summarised.
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binding of Phytochrome b to its nuclear signalling partner pif3 is reversibly induced by light
Nature, 1999Co-Authors: Peter H Quail, Min Ni, James M TeppermanAbstract:The Phytochrome photoreceptor family directs plant gene expression by switching between biologically inactive and active conformers in response to the sequential absorption of red and far-red photons1,2. Several intermediates that act late in the Phytochrome signalling pathway have been identified, but fewer have been identified that act early in the pathway3,4. We have cloned a nuclear basic helix–loop–helix protein, PIF3, which can bind to non-photoactive carboxy-terminal fragments of Phytochromes A and B and functions in Phytochrome signalling in vivo5. Here we show that full-length photoactive Phytochrome B binds PIF3 in vitro only upon light-induced conversion to its active form, and that photoconversion back to its inactive form causes dissociation from PIF3. We conclude that photosensory signalling by Phytochrome B involves light-induced, conformer-specific recognition of the putative transcriptional regulator PIF3, providing a potential mechanism for direct photoregulation of gene expression.
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Are the Phytochromes protein kinases
Protoplasma, 1996Co-Authors: Margaret T. Boylan, Peter H QuailAbstract:The biochemical mechanism of Phytochrome action is unknown. We have examined the proposal, based on sequence similarities to the sensor histidine kinase components of bacterial two-component signaling systems, that the Phytochromes may be functional homologs of these kinases. Four amino acids, three highly conserved between the Phytochrome and bacterial kinase molecules and the other, the histidine residue putatively the target of autophosphorylation, were changed singly in the oat Phytochrome A sequence by in vitro site-directed mutagenesis, and the resultant mutant photo-receptor molecules were assayed for activity by overexpression in transgenic Arabidopsis. Three of the four mutant molecules retained activity equivalent to that of the unmutagenized parent sequence, whereas the fourth mutant could not be evaluated because of low expression. The data show that the former three mutagenized residues are not essential for Phytochrome A function in transgenic Arabidopsis, but, because of the negative nature of the results, the possibility cannot be precluded that the photoreceptor functions as a protein kinase independent of these residues.
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hy8 a new class of arabidopsis long hypocotyl mutants deficient in functional Phytochrome a
The Plant Cell, 1993Co-Authors: Brian M Parks, Peter H QuailAbstract:Emerging evidence suggests that individual members of the Phytochrome family of photoreceptors may regulate discrete facets of plant photomorphogenesis. We report here the isolation of Phytochrome A mutants of Arabidopsis using a novel screening strategy aimed at detecting seedlings with long hypocotyls in prolonged far-red light. Complementation analysis of 10 selected mutant lines showed that each represents an independent, recessive allele at a new locus, designated hy8. Immunoblot and spectrophotometric analyses of two of these lines, hy8-1 and hy8-2, showed that, whereas Phytochromes B and C are expressed at wild-type levels, Phytochrome A is undetectable, thus indicating that the long hypocotyl phenotype displayed by these mutants is caused by Phytochrome A deficiency. A third allele, hy8-3, expresses wild-type levels of spectrally normal Phytochrome A, suggesting a mutation that has resulted in loss of biological activity in an otherwise photochemically active photoreceptor molecule. Together with physiological experiments, these data provide direct evidence that endogenous Phytochrome A is responsible for the "far-red high irradiance response" of etiolated seedlings, but does not play a major role in mediating responses to prolonged red or white light. Because the hy8 and the Phytochrome B-deficient hy3 mutants exhibit reciprocal responsivity toward prolonged red and far-red light, respectively, the evidence indicates that Phytochromes A and B have distinct photosensory roles in regulating seedling development.
Elise K. Pasoreck - One of the best experts on this subject based on the ideXlab platform.
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Phytochrome activates the plastid-encoded RNA polymerase for chloroplast biogenesis via nucleus-to-plastid signaling
Nature Communications, 2019Co-Authors: Elise K. Pasoreck, Detlef Weigel, He Wang, Gregor M. Blaha, Meng ChenAbstract:Light initiates chloroplast biogenesis by activating photosynthesis-associated genes encoded by not only the nuclear but also the plastidial genome, but how photoreceptors control plastidial gene expression remains enigmatic. Here we show that the photoactivation of Phytochromes triggers the expression of photosynthesis-associated plastid-encoded genes ( PhAPG s) by stimulating the assembly of the bacterial-type plastidial RNA polymerase (PEP) into a 1000-kDa complex. Using forward genetic approaches, we identified REGULATOR OF CHLOROPLAST BIOGENESIS (RCB) as a dual-targeted nuclear/plastidial Phytochrome signaling component required for PEP assembly. Surprisingly, RCB controls PhAPG expression primarily from the nucleus by interacting with Phytochromes and promoting their localization to photobodies for the degradation of the transcriptional regulators PIF1 and PIF3. RCB-dependent PIF degradation in the nucleus signals the plastids for PEP assembly and PhAPG expression. Thus, our findings reveal the framework of a nucleus-to-plastid anterograde signaling pathway by which Phytochrome signaling in the nucleus controls plastidial transcription. Light initiates chloroplast biogenesis by controlling gene expression in plastids. Here Yoo et al. show that nuclear Phytochrome signaling triggers plastid gene expression via a novel dual-localized protein necessary for nuclear Phytochrome signaling and subsequent anterograde signaling to the plastid.
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Phytochrome activates the plastid encoded rna polymerase for chloroplast biogenesis via nucleus to plastid signaling
Nature Communications, 2019Co-Authors: Elise K. Pasoreck, Detlef Weigel, He Wang, Gregor M. Blaha, Meng ChenAbstract:Light initiates chloroplast biogenesis by activating photosynthesis-associated genes encoded by not only the nuclear but also the plastidial genome, but how photoreceptors control plastidial gene expression remains enigmatic. Here we show that the photoactivation of Phytochromes triggers the expression of photosynthesis-associated plastid-encoded genes (PhAPGs) by stimulating the assembly of the bacterial-type plastidial RNA polymerase (PEP) into a 1000-kDa complex. Using forward genetic approaches, we identified REGULATOR OF CHLOROPLAST BIOGENESIS (RCB) as a dual-targeted nuclear/plastidial Phytochrome signaling component required for PEP assembly. Surprisingly, RCB controls PhAPG expression primarily from the nucleus by interacting with Phytochromes and promoting their localization to photobodies for the degradation of the transcriptional regulators PIF1 and PIF3. RCB-dependent PIF degradation in the nucleus signals the plastids for PEP assembly and PhAPG expression. Thus, our findings reveal the framework of a nucleus-to-plastid anterograde signaling pathway by which Phytochrome signaling in the nucleus controls plastidial transcription.
Sarah Mathews - One of the best experts on this subject based on the ideXlab platform.
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Phytochrome diversity in green plants and the origin of canonical plant Phytochromes
Nature Communications, 2015Co-Authors: Faywei Li, Michael Melkonian, Carl J Rothfels, Juan Carlos Villarreal, Dennis W Stevenson, Sean W Graham, Gane Kashu Wong, Kathleen M Pryer, Sarah MathewsAbstract:Phytochromes are red/far-red photoreceptors that play essential roles in diverse plant morphogenetic and physiological responses to light. Despite their functional significance, Phytochrome diversity and evolution across photosynthetic eukaryotes remain poorly understood. Using newly available transcriptomic and genomic data we show that canonical plant Phytochromes originated in a common ancestor of streptophytes (charophyte algae and land plants). Phytochromes in charophyte algae are structurally diverse, including canonical and non-canonical forms, whereas in land plants, Phytochrome structure is highly conserved. Liverworts, hornworts and Selaginella apparently possess a single Phytochrome, whereas independent gene duplications occurred within mosses, lycopods, ferns and seed plants, leading to diverse Phytochrome families in these clades. Surprisingly, the Phytochrome portions of algal and land plant neochromes, a chimera of Phytochrome and phototropin, appear to share a common origin. Our results reveal novel Phytochrome clades and establish the basis for understanding Phytochrome functional evolution in land plants and their algal relatives.
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Phytochrome mediated development in land plants red light sensing evolves to meet the challenges of changing light environments
Molecular Ecology, 2006Co-Authors: Sarah MathewsAbstract:Phytochromes are photoreceptors that provide plants with circadian, seasonal, and positional information critical for the control of germination, seedling development, shade avoidance, reproduction, dormancy, and sleep movements. Phytochromes are unique among photoreceptors in their capacity to interconvert between a red-absorbing form (absorption maximum of ∼660 nm) and a far-red absorbing form (absorption maximum of ∼730 nm), which occur in a dynamic equilibrium within plant cells, corresponding to the proportions of red and far-red energy in ambient light. Because pigments in stems and leaves absorb wavelengths below about 700 nm, this provides plants with an elegant system for detecting their position relative to other plants, with which the plants compete for light. Certain aspects of Phytochrome-mediated development outside of flowering plants are strikingly similar to those that have been characterized in Arabidopsis thaliana and other angiosperms. However, early diverging land plants have fewer distinct Phytochrome gene lineages, suggesting that both diversification and subfunctionalization have been important in the evolution of the Phytochrome gene family. There is evidence that subfunctionalization proceeded by the partitioning among paralogues of photosensory specificity, physiological response modes, and light-regulated gene expression and protein stability. Parallel events of duplication and functional divergence may have coincided with the evolution of canopy shade and the increasing complexity of the light environment. Within angiosperms, patterns of functional divergence are clade-specific and the roles of Phytochromes in A. thaliana change across environments, attesting to the evolutionary flexibility and contemporaneous plasticity of Phytochrome signalling in the control of development.
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the Phytochrome apoprotein family in arabidopsis is encoded by five genes the sequences and expression of phyd and phye
Plant Molecular Biology, 1994Co-Authors: Ted Clack, Sarah Mathews, Robert A. SharrockAbstract:Two novelArabidopsis Phytochrome genes,PHYD andPHYE, are described and evidence is presented that, together with the previously describedPHYA, PHYB andPHYC genes, the primary structures of the complete Phytochrome family of this plant are now known. ThePHYD- andPHYE-encoded proteins are of similar size to the other Phytochrome apoproteins and show sequence similarity along their entire lengths. Hence, red/far-red light sensing in higher plants is mediated by a diverse but structurally conserved group of soluble photoreceptors. The proteins encoded by thePHYD andPHYE genes are more closely related to Phytochrome B than to Phytochromes A or C, indicating that the evolution of thePHY gene family inArabidopsis includes an expansion of a PHYB-related subgroup. The PHYB and PHYD Phytochromes show greater than 80% amino acid sequence identity but the phenotypes ofphyB null mutants demonstrate that these receptor forms are not functionally redundant. The fivePHY mRNAs are, in general, expressed constitutively under varying light conditions, in different plant organs, and over the life cycle of the plant. These observations provide the first description of the structure and expression of a complete Phytochrome family in a higher plant.
Gregor M. Blaha - One of the best experts on this subject based on the ideXlab platform.
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Phytochrome activates the plastid-encoded RNA polymerase for chloroplast biogenesis via nucleus-to-plastid signaling
Nature Communications, 2019Co-Authors: Elise K. Pasoreck, Detlef Weigel, He Wang, Gregor M. Blaha, Meng ChenAbstract:Light initiates chloroplast biogenesis by activating photosynthesis-associated genes encoded by not only the nuclear but also the plastidial genome, but how photoreceptors control plastidial gene expression remains enigmatic. Here we show that the photoactivation of Phytochromes triggers the expression of photosynthesis-associated plastid-encoded genes ( PhAPG s) by stimulating the assembly of the bacterial-type plastidial RNA polymerase (PEP) into a 1000-kDa complex. Using forward genetic approaches, we identified REGULATOR OF CHLOROPLAST BIOGENESIS (RCB) as a dual-targeted nuclear/plastidial Phytochrome signaling component required for PEP assembly. Surprisingly, RCB controls PhAPG expression primarily from the nucleus by interacting with Phytochromes and promoting their localization to photobodies for the degradation of the transcriptional regulators PIF1 and PIF3. RCB-dependent PIF degradation in the nucleus signals the plastids for PEP assembly and PhAPG expression. Thus, our findings reveal the framework of a nucleus-to-plastid anterograde signaling pathway by which Phytochrome signaling in the nucleus controls plastidial transcription. Light initiates chloroplast biogenesis by controlling gene expression in plastids. Here Yoo et al. show that nuclear Phytochrome signaling triggers plastid gene expression via a novel dual-localized protein necessary for nuclear Phytochrome signaling and subsequent anterograde signaling to the plastid.
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Phytochrome activates the plastid encoded rna polymerase for chloroplast biogenesis via nucleus to plastid signaling
Nature Communications, 2019Co-Authors: Elise K. Pasoreck, Detlef Weigel, He Wang, Gregor M. Blaha, Meng ChenAbstract:Light initiates chloroplast biogenesis by activating photosynthesis-associated genes encoded by not only the nuclear but also the plastidial genome, but how photoreceptors control plastidial gene expression remains enigmatic. Here we show that the photoactivation of Phytochromes triggers the expression of photosynthesis-associated plastid-encoded genes (PhAPGs) by stimulating the assembly of the bacterial-type plastidial RNA polymerase (PEP) into a 1000-kDa complex. Using forward genetic approaches, we identified REGULATOR OF CHLOROPLAST BIOGENESIS (RCB) as a dual-targeted nuclear/plastidial Phytochrome signaling component required for PEP assembly. Surprisingly, RCB controls PhAPG expression primarily from the nucleus by interacting with Phytochromes and promoting their localization to photobodies for the degradation of the transcriptional regulators PIF1 and PIF3. RCB-dependent PIF degradation in the nucleus signals the plastids for PEP assembly and PhAPG expression. Thus, our findings reveal the framework of a nucleus-to-plastid anterograde signaling pathway by which Phytochrome signaling in the nucleus controls plastidial transcription.
